Co-reporter:Yongye Liang, Hailiang Wang, Jigang Zhou, Yanguang Li, Jian Wang, Tom Regier, and Hongjie Dai
Journal of the American Chemical Society February 22, 2012 Volume 134(Issue 7) pp:3517-3523
Publication Date(Web):January 23, 2012
DOI:10.1021/ja210924t
Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co3O4 nanoparticles, a manganese–cobalt spinel MnCo2O4/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near-edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic–nanocarbon hybrids results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge and nitrogen K-edge XANES showed strongly perturbed C–O and C–N bonding in the N-rmGO sheet, suggesting the formation of C–O–metal and C–N–metal bonds between N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge XANES suggested substitution of Co3+ sites by Mn3+, which increased the activity of the catalytic sites in the hybrid materials, further boosting the ORR activity compared with the pure cobalt oxide hybrid. The covalently bonded hybrid afforded much greater activity and durability than the physical mixture of nanoparticles and carbon materials including N-rmGO. At the same mass loading, the MnCo2O4/N-graphene hybrid can outperform Pt/C in ORR current density at medium overpotentials with stability superior to Pt/C in alkaline solutions.
Co-reporter:Yi Feng;Shoujun Zhu;Alexander L. Antaris;Hao Chen;Yuling Xiao;Xiaowei Lu;Linlin Jiang;Shuo Diao;Kuai Yu;Yan Wang;Sonia Herraiz;Jingying Yue;Xuechuan Hong;Guosong Hong;Zhen Cheng;Aaron J. Hsueh
Chemical Science (2010-Present) 2017 vol. 8(Issue 5) pp:3703-3711
Publication Date(Web):2017/05/03
DOI:10.1039/C6SC04897H
In vivo imaging of hormone receptors provides the opportunity to visualize target tissues under hormonal control in live animals. Detecting longer-wavelength photons in the second near-infrared window (NIR-II, 1000–1700 nm) region affords reduced photon scattering in tissues accompanied by lower autofluorescence, leading to higher spatial resolution at up to centimeter tissue penetration depths. Here, we report the conjugation of a small molecular NIR-II fluorophore CH1055 to a follicle stimulating hormone (FSH-CH) for imaging ovaries and testes in live mice. After exposure to FSH-CH, specific NIR-II signals were found in cultured ovarian granulosa cells containing FSH receptors. Injection of FSH-CH allowed live imaging of ovarian follicles and testicular seminiferous tubules in female and male adult mice, respectively. Using prepubertal mice, NIR-II signals were detected in ovaries containing only preantral follicles. Resolving earlier controversies regarding the expression of FSH receptors in cultured osteoclasts, we detected for the first time specific FSH receptor signals in bones in vivo. The present imaging of FSH receptors in live animals using a ligand-conjugated NIR-II fluorophore with low cell toxicity and rapid clearance allows the development of non-invasive molecular imaging of diverse hormonal target cells in vivo.
Co-reporter:Shoujun Zhu;Qinglai Yang;Alexander L. Antaris;Jingying Yue;Zhuoran Ma;Huasen Wang;Wei Huang;Hao Wan;Joy Wang;Shuo Diao;Bo Zhang;Xiaoyang Li;Yeteng Zhong;Kuai Yu;Guosong Hong;Jian Luo;Yongye Liang
PNAS 2017 Volume 114 (Issue 5 ) pp:962-967
Publication Date(Web):2017-01-31
DOI:10.1073/pnas.1617990114
Fluorescence imaging multiplicity of biological systems is an area of intense focus, currently limited to fluorescence channels
in the visible and first near-infrared (NIR-I; ∼700–900 nm) spectral regions. The development of conjugatable fluorophores
with longer wavelength emission is highly desired to afford more targeting channels, reduce background autofluorescence, and
achieve deeper tissue imaging depths. We have developed NIR-II (1,000–1,700 nm) molecular imaging agents with a bright NIR-II
fluorophore through high-efficiency click chemistry to specific molecular antibodies. Relying on buoyant density differences
during density gradient ultracentrifugation separations, highly pure NIR-II fluorophore-antibody conjugates emitting ∼1,100
nm were obtained for use as molecular-specific NIR-II probes. This facilitated 3D staining of ∼170-μm histological brain tissues
sections on a home-built confocal microscope, demonstrating multicolor molecular imaging across both the NIR-I and NIR-II
windows (800–1,700 nm).
Co-reporter:Xiao-Dong Zhang;Huasen Wang;Alexer L. Antaris;Lulin Li;Shuo Diao;Rui Ma;Andy Nguyen;Guosong Hong;Zhuoran Ma;Joy Wang;Shoujun Zhu;Joseph M. Castellano;Tony Wyss-Coray;Yongye Liang;Jian Luo
Advanced Materials 2016 Volume 28( Issue 32) pp:6872-6879
Publication Date(Web):
DOI:10.1002/adma.201600706
Co-reporter:Ming Gong;Di-Yan Wang;Chia-Chun Chen;Bing-Joe Hwang
Nano Research 2016 Volume 9( Issue 1) pp:28-46
Publication Date(Web):2016 January
DOI:10.1007/s12274-015-0965-x
High gravimetric energy density, earth-abundance, and environmental friendliness of hydrogen sources have inspired the utilization of hydrogen fuel as a clean alternative to fossil fuels. Hydrogen evolution reaction (HER), a half reaction of water splitting, is crucial to the low-cost production of pure H2 fuels but necessitates the use of electrocatalysts to expedite reaction kinetics. Owing to the availability of low-cost oxygen evolution reaction (OER) catalysts for the counter electrode in alkaline media and the lack of low-cost OER catalysts in acidic media, researchers have focused on developing HER catalysts in alkaline media with high activity and stability. Nickel is well-known as an HER catalyst and continuous efforts have been undertaken to improve Ni-based catalysts as alkaline electrolyzers. In this review, we summarize earlier studies of HER activity and mechanism on Ni surfaces, along with recent progress in the optimization of the Ni-based catalysts using various modern techniques. Recently developed Ni-based HER catalysts are categorized according to their chemical nature, and the advantages as well as limitations of each category are discussed. Among all Ni-based catalysts, Ni-based alloys and Ni-based hetero-structure exhibit the most promising electrocatalytic activity and stability owing to the fine-tuning of their surface adsorption properties via a synergistic nearby element or domain. Finally, selected applications of the developed Ni-based HER catalysts are highlighted, such as water splitting, the chloralkali process, and microbial electrolysis cell.
Co-reporter:Guosong Hong, Shuo Diao, Alexander L. Antaris, and Hongjie Dai
Chemical Reviews 2015 Volume 115(Issue 19) pp:10816
Publication Date(Web):May 21, 2015
DOI:10.1021/acs.chemrev.5b00008
Co-reporter:Changxin Chen;Justin Zachary Wu;Kai Tak Lam;Guosong Hong;Ming Gong;Bo Zhang;Yang Lu;Alexer L. Antaris;Shuo Diao;Jing Guo
Advanced Materials 2015 Volume 27( Issue 2) pp:303-309
Publication Date(Web):
DOI:10.1002/adma.201403750
Co-reporter:Yeteng Zhong;Iman Rostami;Zihua Wang;Zhiyuan Hu
Advanced Materials 2015 Volume 27( Issue 41) pp:6418-6422
Publication Date(Web):
DOI:10.1002/adma.201502272
Co-reporter:Di-Yan Wang; Ming Gong; Hung-Lung Chou; Chun-Jern Pan; Hsin-An Chen; Yingpeng Wu; Meng-Chang Lin; Mingyun Guan; Jiang Yang; Chun-Wei Chen; Yuh-Lin Wang; Bing-Joe Hwang; Chia-Chun Chen
Journal of the American Chemical Society 2015 Volume 137(Issue 4) pp:1587-1592
Publication Date(Web):January 14, 2015
DOI:10.1021/ja511572q
Hydrogen evolution reaction (HER) from water through electrocatalysis using cost-effective materials to replace precious Pt catalysts holds great promise for clean energy technologies. In this work we developed a highly active and stable catalyst containing Co doped earth abundant iron pyrite FeS2 nanosheets hybridized with carbon nanotubes (Fe1–xCoxS2/CNT hybrid catalysts) for HER in acidic solutions. The pyrite phase of Fe1–xCoxS2/CNT was characterized by powder X-ray diffraction and absorption spectroscopy. Electrochemical measurements showed a low overpotential of ∼0.12 V at 20 mA/cm2, small Tafel slope of ∼46 mV/decade, and long-term durability over 40 h of HER operation using bulk quantities of Fe0.9Co0.1S2/CNT hybrid catalysts at high loadings (∼7 mg/cm2). Density functional theory calculation revealed that the origin of high catalytic activity stemmed from a large reduction of the kinetic energy barrier of H atom adsorption on FeS2 surface upon Co doping in the iron pyrite structure. It is also found that the high HER catalytic activity of Fe0.9Co0.1S2 hinges on the hybridization with CNTs to impart strong heteroatomic interactions between CNT and Fe0.9Co0.1S2. This work produces the most active HER catalyst based on iron pyrite, suggesting a scalable, low cost, and highly efficient catalyst for hydrogen generation.
Co-reporter:Ming Gong;Dr. Wu Zhou;Michael James Kenney;Rich Kapusta;Sam Cowley;Dr. Yingpeng Wu;Dr. Bingan Lu;Dr. Meng-Chang Lin;Dr. Di-Yan Wang;Dr. Jiang Yang; Bing-Joe Hwang; Hongjie Dai
Angewandte Chemie International Edition 2015 Volume 54( Issue 41) pp:11989-11993
Publication Date(Web):
DOI:10.1002/anie.201504815
Abstract
The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2O3-blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20 mA cm−2 at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. The non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells.
Co-reporter:Shuo Diao;Dr. Jeffrey L. Blackburn;Dr. Guosong Hong;Alexer L. Antaris;Dr. Junlei Chang;Dr. Justin Z. Wu;Bo Zhang;Dr. Kai Cheng; Calvin J. Kuo; Hongjie Dai
Angewandte Chemie International Edition 2015 Volume 54( Issue 49) pp:14758-14762
Publication Date(Web):
DOI:10.1002/anie.201507473
Abstract
Compared to imaging in the visible and near-infrared regions below 900 nm, imaging in the second near-infrared window (NIR-II, 1000–1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly owing to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500–1700 nm, NIR-IIb). With this imaging agent, 3–4 μm wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood-flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR-IIb tumor imaging of a live mouse was explored. NIR-IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high-performance in vivo optical imaging.
Co-reporter:Ming Gong;Dr. Wu Zhou;Michael James Kenney;Rich Kapusta;Sam Cowley;Dr. Yingpeng Wu;Dr. Bingan Lu;Dr. Meng-Chang Lin;Dr. Di-Yan Wang;Dr. Jiang Yang; Bing-Joe Hwang; Hongjie Dai
Angewandte Chemie 2015 Volume 127( Issue 41) pp:12157-12161
Publication Date(Web):
DOI:10.1002/ange.201504815
Abstract
The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2O3-blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20 mA cm−2 at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. The non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells.
Co-reporter:Ming Gong
Nano Research 2015 Volume 8( Issue 1) pp:23-39
Publication Date(Web):2015 January
DOI:10.1007/s12274-014-0591-z
Co-reporter:Shuo Diao;Dr. Jeffrey L. Blackburn;Dr. Guosong Hong;Alexer L. Antaris;Dr. Junlei Chang;Dr. Justin Z. Wu;Bo Zhang;Dr. Kai Cheng; Calvin J. Kuo; Hongjie Dai
Angewandte Chemie 2015 Volume 127( Issue 49) pp:14971-14975
Publication Date(Web):
DOI:10.1002/ange.201507473
Abstract
Compared to imaging in the visible and near-infrared regions below 900 nm, imaging in the second near-infrared window (NIR-II, 1000–1700 nm) is a promising method for deep-tissue high-resolution optical imaging in vivo mainly owing to the reduced scattering of photons traversing through biological tissues. Herein, semiconducting single-walled carbon nanotubes with large diameters were used for in vivo fluorescence imaging in the long-wavelength NIR region (1500–1700 nm, NIR-IIb). With this imaging agent, 3–4 μm wide capillary blood vessels at a depth of about 3 mm could be resolved. Meanwhile, the blood-flow speeds in multiple individual vessels could be mapped simultaneously. Furthermore, NIR-IIb tumor imaging of a live mouse was explored. NIR-IIb imaging can be generalized to a wide range of fluorophores emitting at up to 1700 nm for high-performance in vivo optical imaging.
Co-reporter:Yanguang Li and Hongjie Dai
Chemical Society Reviews 2014 vol. 43(Issue 15) pp:5257-5275
Publication Date(Web):13 Jun 2014
DOI:10.1039/C4CS00015C
Zinc–air is a century-old battery technology but has attracted revived interest recently. With larger storage capacity at a fraction of the cost compared to lithium-ion, zinc–air batteries clearly represent one of the most viable future options to powering electric vehicles. However, some technical problems associated with them have yet to be resolved. In this review, we present the fundamentals, challenges and latest exciting advances related to zinc–air research. Detailed discussion will be organized around the individual components of the system – from zinc electrodes, electrolytes, and separators to air electrodes and oxygen electrocatalysts in sequential order for both primary and electrically/mechanically rechargeable types. The detrimental effect of CO2 on battery performance is also emphasized, and possible solutions summarized. Finally, other metal–air batteries are briefly overviewed and compared in favor of zinc–air.
Co-reporter:Ming Gong, Yanguang Li, Hongbo Zhang, Bo Zhang, Wu Zhou, Ju Feng, Hailiang Wang, Yongye Liang, Zhuangjun Fan, Jie Liu and Hongjie Dai
Energy & Environmental Science 2014 vol. 7(Issue 6) pp:2025-2032
Publication Date(Web):21 Mar 2014
DOI:10.1039/C4EE00317A
High-performance, low-cost, safe and environmentally friendly batteries are important for portable electronics and electric vehicles. Here, we synthesized NiAlCo-layered double hydroxide (LDH) nanoplates attached to few-walled carbon nanotubes (NiAlCo LDH/CNT) as the cathode material of a rechargeable NiZn battery in aqueous alkaline electrolytes. The α-phase nickel hydroxide with ultrathin morphology and strong coupling to nanotubes afforded a cathode with a high capacity of ∼354 mA h g−1 and ∼278 mA h g−1 at current densities of 6.7 A g−1 and 66.7 A g−1, respectively. Al and Co co-doping is unique for stabilizing α-phase nickel hydroxide with only a small capacity loss of ∼6% over 2000 charge and discharge cycles at 66.7 A g−1. Rechargeable ultrafast NiZn batteries with NiAlCo LDH/CNT cathode and a zinc anode can deliver a cell voltage of ∼1.75 V, energy density of ∼274 W h kg−1 and power density of ∼16 kW kg−1 (based on active materials) with a charging time of <1 minute. The results open the possibility of ultrafast and safe batteries with high energy density.
Co-reporter:Justin Wu;Alexer Antaris;Ming Gong
Advanced Materials 2014 Volume 26( Issue 35) pp:6151-6156
Publication Date(Web):
DOI:10.1002/adma.201401108
Co-reporter:Bo Zhang, Jiang Yang, Yingping Zou, Ming Gong, Hui Chen, Guosong Hong, Alexander L. Antaris, Xiaoyang Li, Chien-Liang Liu, Changxin Chen and Hongjie Dai
Chemical Science 2014 vol. 5(Issue 10) pp:4070-4075
Publication Date(Web):09 Jun 2014
DOI:10.1039/C4SC01206B
Micro-bead based multiplexed protein immunoassays have experienced rapid growth in the past decade. Thus far, bead based protein assays have relied on the bulky 240 kDa protein phycoerythrin (PE) as the reporter dye to afford a sufficient detection signal and sensitivity, taking advantage of the 25 fluorophores in each protein. Here, we report the synthesis of gold nano-island coated glass beads (4–8 μm) through a two-step seeding-and-growth approach. We developed flow cytometric bead assays with sensitivities as low as 10 fM (∼0.2 pg ml−1) by utilizing the strong fluorescence enhancement of small molecule fluorophores (Cy-5) on the plasmonic gold (pGOLD) beads. By using different fluorescence tags to label the gold beads and varying the bead size, we obtained multiplexed plasmonic gold beads for the quantification of human cytokine IL-6, IFN-gamma, IL-1 beta, VEGF and an ovarian cancer biomarker CA-125 in biologically relevant media. The low limit of detection surpassed those of glass bead based immunoassays by 2 orders of magnitude, demonstrating the potential of plasmonic gold beads for sensitive protein biomarker quantification.
Co-reporter:Yongye Liang, Yanguang Li, Hailiang Wang, and Hongjie Dai
Journal of the American Chemical Society 2013 Volume 135(Issue 6) pp:2013-2036
Publication Date(Web):January 22, 2013
DOI:10.1021/ja3089923
Electrochemical systems, such as fuel cell and water splitting devices, represent some of the most efficient and environmentally friendly technologies for energy conversion and storage. Electrocatalysts play key roles in the chemical processes but often limit the performance of the entire systems due to insufficient activity, lifetime, or high cost. It has been a long-standing challenge to develop efficient and durable electrocatalysts at low cost. In this Perspective, we present our recent efforts in developing strongly coupled inorganic/nanocarbon hybrid materials to improve the electrocatalytic activities and stability of inorganic metal oxides, hydroxides, sulfides, and metal–nitrogen complexes. The hybrid materials are synthesized by direct nucleation, growth, and anchoring of inorganic nanomaterials on the functional groups of oxidized nanocarbon substrates including graphene and carbon nanotubes. This approach affords strong chemical attachment and electrical coupling between the electrocatalytic nanoparticles and nanocarbon, leading to nonprecious metal-based electrocatalysts with improved activity and durability for the oxygen reduction reaction for fuel cells and chlor-alkali catalysis, oxygen evolution reaction, and hydrogen evolution reaction. X-ray absorption near-edge structure and scanning transmission electron microscopy are employed to characterize the hybrids materials and reveal the coupling effects between inorganic nanomaterials and nanocarbon substrates. Z-contrast imaging and electron energy loss spectroscopy at single atom level are performed to investigate the nature of catalytic sites on ultrathin graphene sheets. Nanocarbon-based hybrid materials may present new opportunities for the development of electrocatalysts meeting the requirements of activity, durability, and cost for large-scale electrochemical applications.
Co-reporter:Ming Gong ; Yanguang Li ; Hailiang Wang ; Yongye Liang ; Justin Z. Wu ; Jigang Zhou ; Jian Wang ; Tom Regier ; Fei Wei
Journal of the American Chemical Society 2013 Volume 135(Issue 23) pp:8452-8455
Publication Date(Web):May 23, 2013
DOI:10.1021/ja4027715
Highly active, durable, and cost-effective electrocatalysts for water oxidation to evolve oxygen gas hold a key to a range of renewable energy solutions, including water-splitting and rechargeable metal–air batteries. Here, we report the synthesis of ultrathin nickel–iron layered double hydroxide (NiFe-LDH) nanoplates on mildly oxidized multiwalled carbon nanotubes (CNTs). Incorporation of Fe into the nickel hydroxide induced the formation of NiFe-LDH. The crystalline NiFe-LDH phase in nanoplate form is found to be highly active for oxygen evolution reaction in alkaline solutions. For NiFe-LDH grown on a network of CNTs, the resulting NiFe-LDH/CNT complex exhibits higher electrocatalytic activity and stability for oxygen evolution than commercial precious metal Ir catalysts.
Co-reporter:Dr. Zhimin Tao;Guosong Hong;Chihiro Shinji;Dr. Changxin Chen;Shuo Diao;Alexer L. Antaris;Bo Zhang;Dr. Yingping Zou ; Hongjie Dai
Angewandte Chemie 2013 Volume 125( Issue 49) pp:13240-13244
Publication Date(Web):
DOI:10.1002/ange.201307346
Co-reporter:Dr. Zhimin Tao;Guosong Hong;Chihiro Shinji;Dr. Changxin Chen;Shuo Diao;Alexer L. Antaris;Bo Zhang;Dr. Yingping Zou ; Hongjie Dai
Angewandte Chemie International Edition 2013 Volume 52( Issue 49) pp:13002-13006
Publication Date(Web):
DOI:10.1002/anie.201307346
Co-reporter:Bo Zhang;Jordan Price;Guosong Hong;Scott M. Tabakman;Hailiang Wang
Nano Research 2013 Volume 6( Issue 2) pp:113-120
Publication Date(Web):2013 February
DOI:10.1007/s12274-012-0286-2
Protein microarrays based on fluorescence detection have been widely utilized for high-throughput functional proteomic analysis. However, a drawback of such assays has been low sensitivity and narrow dynamic range, limiting their capabilities, especially for detecting low abundance biological molecules such as cytokines in human samples. Here, we present fluorescence-enhancing microarrays on plasmonic gold films for multiplexed cytokine detection with up to three orders of magnitude higher sensitivity than on conventional nitrocellulose and glass substrates. Cytokine detection on the gold plasmonic substrate is about one to two orders of magnitude more sensitive than enzyme-linked immunosorbent assay (ELISA) and can be multiplexed. A panel of six cytokines (Vascular endothelial growth factor (VEGF), Interleukin 1β (IL-1β), Interleukin 4 (IL-4), Interleukin 6 (IL-6), Interferon γ (IFN-γ), and Tumor necrosis factor (TNF)) were detected in the culture media of cancer cells. This work establishes a new method of high throughput multiplexed cytokine detection with higher sensitivity and dynamic range than ELISA.
Co-reporter:Michael J. Kenney;Justin Z. Wu;Yanguang Li;Mario Lanza;Ju Feng;Ming Gong
Science 2013 Volume 342(Issue 6160) pp:836-840
Publication Date(Web):15 Nov 2013
DOI:10.1126/science.1241327
Stabilizing Silicon
Solar-driven water splitting has potential as an energy storage mechanism to supplement the direct conversion of sunlight to electricity. A submersed integrated device has been proposed both to absorb the light and to catalyze the reaction, but stability has been a problem. Kenney et al. (p. 836; see the Perspective by Turner) found that a nickel coating, thin enough to let light through, could protect a silicon absorber in the alkaline environment of a lithium/potassium borate electrolyte. The nickel also functioned as the oxidation catalyst, and the lithium ions helped to establish a protective film structure in situ.
Co-reporter:Hailiang Wang, Yuan Yang, Yongye Liang, Guangyuan Zheng, Yanguang Li, Yi Cui and Hongjie Dai
Energy & Environmental Science 2012 vol. 5(Issue 7) pp:7931-7935
Publication Date(Web):23 Apr 2012
DOI:10.1039/C2EE21746E
We employ a MnCo2O4–graphene hybrid material as the cathode catalyst for Li–O2 batteries with a non-aqueous electrolyte. The hybrid is synthesized by direct nucleation and growth of MnCo2O4 nanoparticles on reduced graphene oxide, which controls the morphology, size and distribution of the oxide nanoparticles and renders strong covalent coupling between the oxide nanoparticles and the electrically conducting graphene substrate. The inherited excellent catalytic activity of the hybrid leads to lower overpotentials and longer cycle lives of Li–O2 cells than other catalysts including noble metals such as platinum. We also study the relationships between the charging–discharging performance of Li–O2 cells and the oxygen reduction and oxygen evolution activity of catalysts in both aqueous and non-aqueous solutions.
Co-reporter:Joshua T. Robinson ; Guosong Hong ; Yongye Liang ; Bo Zhang ; Omar K. Yaghi
Journal of the American Chemical Society 2012 Volume 134(Issue 25) pp:10664-10669
Publication Date(Web):June 5, 2012
DOI:10.1021/ja303737a
Cancer imaging requires selective high accumulation of contrast agents in the tumor region and correspondingly low uptake in healthy tissues. Here, by making use of a novel synthetic polymer to solubilize single-walled carbon nanotubes (SWNTs), we prepared a well-functionalized SWNT formulation with long blood circulation (half-life of ∼30 h) in vivo to achieve ultrahigh accumulation of ∼30% injected dose (ID)/g in 4T1 murine breast tumors in Balb/c mice. Functionalization dependent blood circulation and tumor uptake were investigated through comparisons with phospholipid-PEG solubilized SWNTs. For the first time, we performed video-rate imaging of tumors based on the intrinsic fluorescence of SWNTs in the second near-infrared (NIR-II, 1.1–1.4 μm) window. We carried out dynamic contrast imaging through principal component analysis (PCA) to immediately pinpoint the tumor within ∼20 s after injection. Imaging over time revealed increasing tumor contrast up to 72 h after injection, allowing for its unambiguous identification. The 3D reconstruction of the SWNTs distribution based on their stable photoluminescence inside the tumor revealed a high degree of colocalization of SWNTs and blood vessels, suggesting enhanced permeability and retention (EPR) effect as the main cause of high passive tumor uptake of the nanotubes.
Co-reporter:Yongye Liang ; Hailiang Wang ; Peng Diao ; Wesley Chang ; Guosong Hong ; Yanguang Li ; Ming Gong ; Liming Xie ; Jigang Zhou ; Jian Wang ; Tom Z. Regier ; Fei Wei
Journal of the American Chemical Society 2012 Volume 134(Issue 38) pp:15849-15857
Publication Date(Web):September 8, 2012
DOI:10.1021/ja305623m
Electrocatalyst for oxygen reduction reaction (ORR) is crucial for a variety of renewable energy applications and energy-intensive industries. The design and synthesis of highly active ORR catalysts with strong durability at low cost is extremely desirable but remains challenging. Here, we used a simple two-step method to synthesize cobalt oxide/carbon nanotube (CNT) strongly coupled hybrid as efficient ORR catalyst by directly growing nanocrystals on oxidized multiwalled CNTs. The mildly oxidized CNTs provided functional groups on the outer walls to nucleate and anchor nanocrystals, while retaining intact inner walls for highly conducting network. Cobalt oxide was in the form of CoO due to a gas-phase annealing step in NH3. The resulting CoO/nitrogen-doped CNT (NCNT) hybrid showed high ORR current density that outperformed Co3O4/graphene hybrid and commercial Pt/C catalyst at medium overpotential, mainly through a 4e reduction pathway. The metal oxide/carbon nanotube hybrid was found to be advantageous over the graphene counterpart in terms of active sites and charge transport. Last, the CoO/NCNT hybrid showed high ORR activity and stability under a highly corrosive condition of 10 M NaOH at 80 °C, demonstrating the potential of strongly coupled inorganic/nanocarbon hybrid as a novel catalyst system in oxygen depolarized cathode for chlor-alkali electrolysis.
Co-reporter:Shuo Diao ; Guosong Hong ; Joshua T. Robinson ; Liying Jiao ; Alexander L. Antaris ; Justin Z. Wu ; Charina L. Choi
Journal of the American Chemical Society 2012 Volume 134(Issue 41) pp:16971-16974
Publication Date(Web):October 3, 2012
DOI:10.1021/ja307966u
The intrinsic band gap photoluminescence of semiconducting single-walled carbon nanotubes (SWNTs) makes them promising biological imaging probes in the second near-infrared (NIR-II, 1.0–1.4 μm) window. Thus far, SWNTs used for biological applications have been a complex mixture of metallic and semiconducting species with random chiralities, preventing simultaneous resonant excitation of all semiconducting nanotubes and emission at a single well-defined wavelength. Here, we developed a simple gel filtration method to enrich semiconducting (12,1) and (11,3) SWNTs with identical resonance absorption at ∼808 nm and emission near ∼1200 nm. The chirality sorted SWNTs showed ∼5-fold higher photoluminescence intensity under resonant excitation of 808 nm than unsorted SWNTs on a per-mass basis. Real-time in vivo video imaging of whole mouse body and tumor vessels was achieved using a ∼6-fold lower injected dose of (12,1) and (11,3) SWNTs (∼3 μg per mouse or ∼0.16 mg/kg of body weight vs 1.0 mg/kg for unsorted SWNTs) than a previous heterogeneous mixture, demonstrating the first resonantly excited and chirality separated SWNTs for biological imaging.
Co-reporter:Guosong Hong;Dr. Joshua T. Robinson;Yejun Zhang;Shuo Diao;Alexer L. Antaris; Qiangbin Wang; Hongjie Dai
Angewandte Chemie International Edition 2012 Volume 51( Issue 39) pp:9818-9821
Publication Date(Web):
DOI:10.1002/anie.201206059
Co-reporter:Liying Jiao;Liming Xie
Nano Research 2012 Volume 5( Issue 4) pp:292-296
Publication Date(Web):2012 April
DOI:10.1007/s12274-012-0209-2
Co-reporter:Ju Feng;Yongye Liang;Hailiang Wang;Yanguang Li;Bo Zhang;Jigang Zhou
Nano Research 2012 Volume 5( Issue 10) pp:718-725
Publication Date(Web):2012 October
DOI:10.1007/s12274-012-0256-8
Co-reporter:Zhuang Liu, Joshua T. Robinson, Scott M. Tabakman, Kai Yang, Hongjie Dai
Materials Today 2011 Volume 14(7–8) pp:316-323
Publication Date(Web):July–August 2011
DOI:10.1016/S1369-7021(11)70161-4
Carbon nanotubes and graphene are both low-dimensional sp2 carbon nanomaterials exhibiting many unique physical and chemical properties that are interesting in a wide range of areas including nanomedicine. Since 2004, carbon nanotubes have been extensively explored as drug delivery carriers for the intracellular transport of chemotherapy drugs, proteins, and genes. In vivo cancer treatment with carbon nanotubes has been demonstrated in animal experiments by several different groups. Recently, graphene, another allotrope of carbon, has also shown promise in various biomedical applications. In this article, we will highlight recent research on these two categories of closely related carbon nanomaterials for applications in drug delivery and cancer therapy, and discuss the opportunities and challenges in this rapidly growing field.
Co-reporter:Hailiang Wang, Yuan Yang, Yongye Liang, Joshua Tucker Robinson, Yanguang Li, Ariel Jackson, Yi Cui, and Hongjie Dai
Nano Letters 2011 Volume 11(Issue 7) pp:2644-2647
Publication Date(Web):June 24, 2011
DOI:10.1021/nl200658a
We report the synthesis of a graphene–sulfur composite material by wrapping poly(ethylene glycol) (PEG) coated submicrometer sulfur particles with mildly oxidized graphene oxide sheets decorated by carbon black nanoparticles. The PEG and graphene coating layers are important to accommodating volume expansion of the coated sulfur particles during discharge, trapping soluble polysulfide intermediates, and rendering the sulfur particles electrically conducting. The resulting graphene–sulfur composite showed high and stable specific capacities up to ∼600 mAh/g over more than 100 cycles, representing a promising cathode material for rechargeable lithium batteries with high energy density.
Co-reporter:Joshua T. Robinson ; Scott M. Tabakman ; Yongye Liang ; Hailiang Wang ; Hernan Sanchez Casalongue ; Daniel Vinh
Journal of the American Chemical Society 2011 Volume 133(Issue 17) pp:6825-6831
Publication Date(Web):April 8, 2011
DOI:10.1021/ja2010175
We developed nanosized, reduced graphene oxide (nano-rGO) sheets with high near-infrared (NIR) light absorbance and biocompatibility for potential photothermal therapy. The single-layered nano-rGO sheets were ∼20 nm in average lateral dimension, functionalized noncovalently by amphiphilic PEGylated polymer chains to render stability in biological solutions and exhibited 6-fold higher NIR absorption than nonreduced, covalently PEGylated nano-GO. Attaching a targeting peptide bearing the Arg-Gly-Asp (RGD) motif to nano-rGO afforded selective cellular uptake in U87MG cancer cells and highly effective photoablation of cells in vitro. In the absence of any NIR irradiation, nano-rGO exhibited little toxicity in vitro at concentrations well above the doses needed for photothermal heating. This work established nano-rGO as a novel photothermal agent due to its small size, high photothermal efficiency, and low cost as compared to other NIR photothermal agents including gold nanomaterials and carbon nanotubes.
Co-reporter:Yanguang Li ; Hailiang Wang ; Liming Xie ; Yongye Liang ; Guosong Hong
Journal of the American Chemical Society 2011 Volume 133(Issue 19) pp:7296-7299
Publication Date(Web):April 21, 2011
DOI:10.1021/ja201269b
Advanced materials for electrocatalytic and photoelectrochemical water splitting are central to the area of renewable energy. In this work, we developed a selective solvothermal synthesis of MoS2 nanoparticles on reduced graphene oxide (RGO) sheets suspended in solution. The resulting MoS2/RGO hybrid material possessed nanoscopic few-layer MoS2 structures with an abundance of exposed edges stacked onto graphene, in strong contrast to large aggregated MoS2 particles grown freely in solution without GO. The MoS2/RGO hybrid exhibited superior electrocatalytic activity in the hydrogen evolution reaction (HER) relative to other MoS2 catalysts. A Tafel slope of ∼41 mV/decade was measured for MoS2 catalysts in the HER for the first time; this exceeds by far the activity of previous MoS2 catalysts and results from the abundance of catalytic edge sites on the MoS2 nanoparticles and the excellent electrical coupling to the underlying graphene network. The ∼41 mV/decade Tafel slope suggested the Volmer–Heyrovsky mechanism for the MoS2-catalyzed HER, with electrochemical desorption of hydrogen as the rate-limiting step.
Co-reporter:Hailiang Wang;Yongye Liang;Tissaphern Mirfakhrai;Zhuo Chen
Nano Research 2011 Volume 4( Issue 8) pp:729-736
Publication Date(Web):2011 August
DOI:10.1007/s12274-011-0129-6
Supercapacitors operating in aqueous solutions are low cost energy storage devices with high cycling stability and fast charging and discharging capabilities, but generally suffer from low energy densities. Here, we grow Ni(OH)2 nanoplates and RuO2 nanoparticles on high quality graphene sheets in order to maximize the specific capacitances of these materials. We then pair up a Ni(OH)2/graphene electrode with a RuO2/graphene electrode to afford a high performance asymmetrical supercapacitor with high energy and power density operating in aqueous solutions at a voltage of ∼1.5 V. The asymmetrical supercapacitor exhibits significantly higher energy densities than symmetrical RuO2-RuO2 supercapacitors or asymmetrical supercapacitors based on either RuO2-carbon or Ni(OH)2-carbon electrode pairs. A high energy density of ∼48 W·h/kg at a power density of ∼0.23 kW/kg, and a high power density of ∼21 kW/kg at an energy density of ∼14 W·h/kg have been achieved with our Ni(OH)2/graphene and RuO2/graphene asymmetrical supercapacitor. Thus, pairing up metal-oxide/graphene and metal-hydroxide/graphene hybrid materials for asymmetrical supercapacitors represents a new approach to high performance energy storage.
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Co-reporter:Sarah P. Sherlock, Scott M. Tabakman, Liming Xie, and Hongjie Dai
ACS Nano 2011 Volume 5(Issue 2) pp:1505
Publication Date(Web):February 1, 2011
DOI:10.1021/nn103415x
FeCo/graphitic carbon shell (FeCo/GC) nanocrystals (∼4−5 nm in diameter) with ultrahigh magnetization are synthesized, functionalized, and developed into multifunctional biocompatible materials. We demonstrate the ability of this material to serve as an integrated system for combined drug delivery, near-infrared (NIR) photothermal therapy, and magnetic resonance imaging (MRI) in vitro. We show highly efficient loading of doxorubicin (DOX) by π-stacking on the graphitic shell to afford FeCo/GC−DOX complexes and pH sensitive DOX release from the particles. We observe enhanced intracellular drug delivery by FeCo/GC−DOX under 20 min of NIR laser (808 nm) induced hyperthermia to 43 °C, resulting in a significant increase of FeCo/GC−DOX toxicity toward breast cancer cells. The synergistic cancer cell killing by FeCo/GC−DOX drug delivery under photothermal heating is due to a ∼two-fold enhancement of cancer cell uptake of FeCo/GC−DOX complex and the increased DOX toxicity under the 43 °C hyperthermic condition. The combination of synergistic NIR photothermally enhanced drug delivery and MRI with the FeCo/GC nanocrystals could lead to a powerful multimodal system for biomedical detection and therapy.Keywords: doxorubicin; drug delivery; MRI; multifunctional nanoparticle; photothermal; supramolecular chemistry
Co-reporter:Hailiang Wang;Yongye Liang;Yanguang Li ; Hongjie Dai
Angewandte Chemie 2011 Volume 123( Issue 46) pp:11161-11164
Publication Date(Web):
DOI:10.1002/ange.201104004
Co-reporter:Guosong Hong;Scott M. Tabakman;Dr. Kevin Welsher;Dr. Zhuo Chen;Joshua T. Robinson;Hailiang Wang;Bo Zhang; Hongjie Dai
Angewandte Chemie International Edition 2011 Volume 50( Issue 20) pp:4644-4648
Publication Date(Web):
DOI:10.1002/anie.201100934
Co-reporter:Hailiang Wang;Yuan Yang;Yongye Liang;Li-Feng Cui;Hernan SanchezCasalongue;Yanguang Li;Guosong Hong; Yi Cui; Hongjie Dai
Angewandte Chemie International Edition 2011 Volume 50( Issue 32) pp:7364-7368
Publication Date(Web):
DOI:10.1002/anie.201103163
Co-reporter:Hailiang Wang;Yongye Liang;Yanguang Li ; Hongjie Dai
Angewandte Chemie International Edition 2011 Volume 50( Issue 46) pp:10969-10972
Publication Date(Web):
DOI:10.1002/anie.201104004
Co-reporter:Guosong Hong;Scott M. Tabakman;Dr. Kevin Welsher;Dr. Zhuo Chen;Joshua T. Robinson;Hailiang Wang;Bo Zhang; Hongjie Dai
Angewandte Chemie 2011 Volume 123( Issue 20) pp:4740-4744
Publication Date(Web):
DOI:10.1002/ange.201100934
Co-reporter:Hailiang Wang ; Joshua Tucker Robinson ; Georgi Diankov
Journal of the American Chemical Society 2010 Volume 132(Issue 10) pp:3270-3271
Publication Date(Web):February 18, 2010
DOI:10.1021/ja100329d
We show a general two-step method for growing hydroxide and oxide nanocrystals of the iron family elements (Ni, Co, Fe) on graphene with two degrees of oxidation. Drastically different nanocrystal growth behaviors were observed on low-oxidation graphene sheets (GS) and highly oxidized graphite oxide (GO) in hydrothermal reactions. Small particles precoated on GS with few oxygen-containing surface groups diffused and recrystallized into single-crystalline Ni(OH)2 hexagonal nanoplates or Fe2O3 nanorods with well-defined morphologies. In contrast, particles precoated on GO were pinned by the high-concentration oxygen groups and defects on GO without recrystallization into well-defined shapes. Adjusting the reaction temperature can be included to further control materials grown on graphene. For materials with weak interactions with graphene, increasing the reaction temperature can lead to diffusion and recrystallization of surface species into larger crystals, even on highly oxidized and defective GO. Our results suggest an interesting new approach for controlling the morphology of nanomaterials grown on graphene by tuning the surface chemistry of graphene substrates used for crystal nucleation and growth.
Co-reporter:Hailiang Wang ; Hernan Sanchez Casalongue ; Yongye Liang
Journal of the American Chemical Society 2010 Volume 132(Issue 21) pp:7472-7477
Publication Date(Web):May 5, 2010
DOI:10.1021/ja102267j
Ni(OH)2 nanocrystals grown on graphene sheets with various degrees of oxidation are investigated as electrochemical pseudocapacitor materials for potential energy storage applications. Single-crystalline Ni(OH)2 hexagonal nanoplates directly grown on lightly oxidized, electrically conducting graphene sheets (GS) exhibit a high specific capacitance of ∼1335 F/g at a charge and discharge current density of 2.8 A/g and ∼953 F/g at 45.7 A/g with excellent cycling ability. The high specific capacitance and remarkable rate capability are promising for applications in supercapacitors with both high energy and power densities. A simple physical mixture of pre-synthesized Ni(OH)2 nanoplates and graphene sheets shows lower specific capacitance, highlighting the importance of direct growth of nanomaterials on graphene to impart intimate interactions and efficient charge transport between the active nanomaterials and the conducting graphene network. Single-crystalline Ni(OH)2 nanoplates directly grown on graphene sheets also significantly outperform small Ni(OH)2 nanoparticles grown on heavily oxidized, electrically insulating graphite oxide (GO), suggesting that the electrochemical performance of these composites is dependent on the quality of graphene substrates and the morphology and crystallinity of the nanomaterials grown on top. These results suggest the importance of rational design and synthesis of graphene-based nanocomposite materials for high-performance energy applications.
Co-reporter:Guosong Hong ; Scott M. Tabakman ; Kevin Welsher ; Hailiang Wang ; Xinran Wang
Journal of the American Chemical Society 2010 Volume 132(Issue 45) pp:15920-15923
Publication Date(Web):October 27, 2010
DOI:10.1021/ja1087997
The photoluminescence (PL) quantum yield of single-walled carbon nanotubes (SWNTs) is relatively low, with various quenching effects by metallic species reported in the literature. Here, we report the first case of metal enhanced fluorescence (MEF) of surfactant-coated carbon nanotubes on nanostructured gold substrates. The photoluminescence quantum yield of SWNTs is observed to be enhanced more than 10-fold. The dependence of fluorescence enhancement on metal−nanotube distance and on the surface plasmon resonance (SPR) of the gold substrate for various SWNT chiralities is measured to reveal the mechanism of enhancement. Surfactant-coated SWNTs in direct contact with metal exhibit strong MEF without quenching, suggesting a small quenching distance for SWNTs on the order of the van der Waals distance, beyond which the intrinsically fast nonradiative decay rate in nanotubes is little enhanced by metal. The metal enhanced fluorescence of SWNTs is attributed to radiative lifetime shortening through resonance coupling of SWNT emission to the reradiating dipolar plasmonic modes in the metal.
Co-reporter:Jin Hyung Lee;Sarah P. Sherlock;Masahiro Terashima;Hisanori Kosuge;Yoriyasu Suzuki;Andrew Goodwin;Joshua Robinson;Won Seok Seo;Zhuang Liu;Richard Luong;Michael V. McConnell;Dwight G. Nishimura
Magnetic Resonance in Medicine 2010 Volume 63( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/mrm.22343
No abstract is available for this article.
Co-reporter:Scott M. Tabakman ; Kevin Welsher ; Guosong Hong
The Journal of Physical Chemistry C 2010 Volume 114(Issue 46) pp:19569-19575
Publication Date(Web):October 28, 2010
DOI:10.1021/jp106453v
Single-walled carbon nanotubes (SWNTs) are promising materials for in vitro and in vivo biological applications due to their high surface area and inherent near-infrared photoluminescence and Raman scattering properties. Here, we use density gradient centrifugation to separate SWNTs by length and degree of bundling. Following separation, we observe a peak in photoluminescence quantum yield (PL QY) and Raman scattering intensity where the SWNT length is maximized and bundling is minimized. Individualized SWNTs are found to exhibit a high PL QY and high resonance-enhanced Raman scattering intensity. Fractions containing long, individual SWNTs exhibit the highest PL QY and Raman scattering intensities compared with fractions containing single, short SWNTs or SWNT bundles. Intensity gains of approximately ∼1.7- and 4-fold, respectively, are obtained compared with the starting material. Spectroscopic analysis reveals that SWNT fractions at higher displacement contain increasing proportions of SWNT bundles, which causes reduced optical transition energies and broadening of absorption features in the UV−vis-NIR spectra and reduced PL QYs and Raman scattering intensities. Finally, we adsorb small aromatic species on “bright,” individualized SWNT sidewalls and compare the resulting absorption, PL, and Raman scattering effects to that of SWNT bundles. We observe similar effects in both cases, suggesting that aromatic stacking affects the optical properties of SWNTs in an analogous way to SWNT bundles, likely due to electronic structure perturbations, charge transfer, and dielectric screening effects, resulting in reduction of the excitonic optical transition energies and exciton lifetimes.
Co-reporter:Joshua T. Robinson;Kevin Welsher;Scott M. Tabakman;Sarah P. Sherlock
Nano Research 2010 Volume 3( Issue 11) pp:779-793
Publication Date(Web):2010 November
DOI:10.1007/s12274-010-0045-1
Short single-walled carbon nanotubes (SWNTs) functionalized by PEGylated phospholipids are biologically non-toxic and long-circulating nanomaterials with intrinsic near infrared photoluminescence (NIR PL), characteristic Raman spectra, and strong optical absorbance in the near infrared (NIR). This work demonstrates the first dual application of intravenously injected SWNTs as photoluminescent agents for in vivo tumor imaging in the 1.0–1.4 μm emission region and as NIR absorbers and heaters at 808 nm for photothermal tumor elimination at the lowest injected dose (70 μg of SWNT/mouse, equivalent to 3.6 mg/kg) and laser irradiation power (0.6 W/cm2) reported to date. Ex vivo resonance Raman imaging revealed the SWNT distribution within tumors at a high spatial resolution. Complete tumor elimination was achieved for large numbers of photothermally treated mice without any toxic side effects after more than six months post-treatment. Further, side-by-side experiments were carried out to compare the performance of SWNTs and gold nanorods (AuNRs) at an injected dose of 700 μg of AuNR/mouse (equivalent to 35 mg/kg) in NIR photothermal ablation of tumors in vivo. Highly effective tumor elimination with SWNTs was achieved at 10 times lower injected doses and lower irradiation powers than for AuNRs. These results suggest there are significant benefits of utilizing the intrinsic properties of biocompatible SWNTs for combined cancer imaging and therapy.
Co-reporter:Zhuang Liu;Scott Tabakman;Sarah Sherlock;Xiaolin Li;Zhuo Chen
Nano Research 2010 Volume 3( Issue 3) pp:222-233
Publication Date(Web):2010 March
DOI:10.1007/s12274-010-1025-1
Co-reporter:Yongye Liang;Hailiang Wang;Hernan Sanchez Casalongue;Zhuo Chen
Nano Research 2010 Volume 3( Issue 10) pp:701-705
Publication Date(Web):2010 October
DOI:10.1007/s12274-010-0033-5
A graphene/TiO2 nanocrystals hybrid has been successfully prepared by directly growing TiO2 nanocrystals on graphene oxide (GO) sheets. The direct growth of the nanocrystals on GO sheets was achieved by a two-step method, in which TiO2 was first coated on GO sheets by hydrolysis and crystallized into anatase nanocrystals by hydrothermal treatment in the second step. Slow hydrolysis induced by the use of EtOH/H2O mixed solvent and addition of H2SO4 facilitates the selective growth of TiO2 on GO and suppresses growth of free TiO2 in solution. The method offers easy access to the GO/TiO2 nanocrystals hybrid with a uniform coating and strong interactions between TiO2 and the underlying GO sheets. The strong coupling gives advanced hybrid materials with various applications including photocatalysis. The prepared graphene/TiO2 nanocrystals hybrid has superior photocatalytic activity to other TiO2 materials in the degradation of rhodamine B, showing an impressive three-fold photocatalytic enhancement over P25. It is expected that the hybrid material could also be promising for various other applications including lithium ion batteries, where strong electrical coupling to TiO2 nanoparticles is essential.
Co-reporter:Liying Jiao;Li Zhang;Lei Ding;Jie Liu
Nano Research 2010 Volume 3( Issue 6) pp:387-394
Publication Date(Web):2010 June
DOI:10.1007/s12274-010-1043-z
Aligned graphene nanoribbon (GNR) arrays have been made by unzipping of aligned single-walled and few-walled carbon nanotube (CNT) arrays. Nanotube unzipping was achieved by a polymer-protected Ar plasma etching method, and the resulting nanoribbon array can be transferred onto any chosen substrate. Atomic force microscope (AFM) imaging and Raman mapping on the same CNTs before and after unzipping confirmed that ˜80% of CNTs were opened up to form single layer sub-10 nm GNRs. Electrical devices made from the GNRs (after annealing in H2 at high temperature) showed on/off current (Ion/Ioff) ratios up to 103 at room temperature, suggesting the semiconducting nature of the narrow GNRs. Novel GNR-GNR and GNR-CNT crossbars were fabricated by transferring GNR arrays across GNR and CNT arrays, respectively. The production of such ordered graphene nanoribbon architectures may allow for large scale integration of GNRs into nanoelectronics or optoelectronics.
Co-reporter:Hailiang Wang ; Joshua Tucker Robinson ; Xiaolin Li
Journal of the American Chemical Society 2009 Volume 131(Issue 29) pp:9910-9911
Publication Date(Web):July 6, 2009
DOI:10.1021/ja904251p
We have developed a solvothermal reduction method that affords more effective reduction of chemically derived graphene sheets and graphite oxide than low-temperature reduction methods. Solvothermal reduction removed oxygen and defects from graphene sheets, increased the size of sp2 domains, and produced materials that were as conducting as pristine graphene and exhibited clear intrinsic Dirac behavior.
Co-reporter:Xiaolin Li ; Hailiang Wang ; Joshua T. Robinson ; Hernan Sanchez ; Georgi Diankov
Journal of the American Chemical Society 2009 Volume 131(Issue 43) pp:15939-15944
Publication Date(Web):October 9, 2009
DOI:10.1021/ja907098f
We developed a simple chemical method to obtain bulk quantities of N-doped, reduced graphene oxide (GO) sheets through thermal annealing of GO in ammonia. X-ray photoelectron spectroscopy (XPS) study of GO sheets annealed at various reaction temperatures reveals that N-doping occurs at a temperature as low as 300 °C, while the highest doping level of ∼5% N is achieved at 500 °C. N-doping is accompanied by the reduction of GO with decreases in oxygen levels from ∼28% in as-made GO down to ∼2% in 1100 °C NH3 reacted GO. XPS analysis of the N binding configurations of doped GO finds pyridinic N in the doped samples, with increased quaternary N (N that replaced the carbon atoms in the graphene plane) in GO annealed at higher temperatures (≥900 °C). Oxygen groups in GO were found responsible for reactions with NH3 and C−N bond formation. Prereduced GO with fewer oxygen groups by thermal annealing in H2 exhibits greatly reduced reactivity with NH3 and a lower N-doping level. Electrical measurements of individual GO sheet devices demonstrate that GO annealed in NH3 exhibits higher conductivity than those annealed in H2, suggesting more effective reduction of GO by annealing in NH3 than in H2, consistent with XPS data. The N-doped reduced GO shows clearly n-type electron doping behavior with the Dirac point (DP) at negative gate voltages in three terminal devices. Our method could lead to the synthesis of bulk amounts of N-doped, reduced GO sheets useful for various practical applications.
Co-reporter:Jin Hyung Lee;Sarah P. Sherlock;Masahiro Terashima;Hisanori Kosuge;Yoriyasu Suzuki;Andrew Goodwin;Joshua Robinson;Won Seok Seo;Zhuang Liu;Richard Luong;Michael V. McConnell;Dwight G. Nishimura
Magnetic Resonance in Medicine 2009 Volume 62( Issue 6) pp:1497-1509
Publication Date(Web):
DOI:10.1002/mrm.22132
Abstract
FeCo-graphitic carbon shell nanocrystals are a novel MRI contrast agent with unprecedented high per-metal-atom-basis relaxivity (r1 = 97 mM-1 sec-1, r2 = 400 mM-1 sec-1) and multifunctional capabilities. While the conventional gadolinium-based contrast-enhanced angiographic magnetic MRI has proven useful for diagnosis of vascular diseases, its short circulation time and relatively low sensitivity render high-resolution MRI of morphologically small vascular structures such as those involved in collateral, arteriogenic, and angiogenic vessel formation challenging. Here, by combining FeCo-graphitic carbon shell nanocrystals with high-resolution MRI technique, we demonstrate that such microvessels down to ∼100 μm can be monitored in high contrast and noninvasively using a conventional 1.5-T clinical MRI system, achieving a diagnostic imaging standard approximating that of the more invasive X-ray angiography. Preliminary in vitro and in vivo toxicity study results also show no sign of toxicity. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
Co-reporter:Youngki Yoon;Peter K. Weber;Hailiang Wang;Jing Guo;Xinran Wang;Li Zhang;Xiaolin Li
Science 2009 Volume 324(Issue 5928) pp:
Publication Date(Web):
DOI:10.1126/science.1170335
Negatively Doped Graphene Nanoribbons
The potential applications in electronic devices of graphene (single atom, thick layers of graphite) would be even greater if it can be accessed in both p- and n-doped forms. Graphene nanoribbons (long strips only tens of nanometers in width) are readily p-doped by adsorbates from the ambient atmosphere. Wang et al. (p. 768) show that when graphene nano-ribbons are electrically heated in an ammonia atmosphere, nitrogen is incorporated mainly at the edges of the ribbon and creates an n-type material. Field-effect transistors that operate at room temperature can be made from this material.
Co-reporter:Zhuang Liu;AliceC. Fan;Kavya Rakhra;Sarah Sherlock;Andrew Goodwin;Xiaoyuan Chen;Qiwei Yang;DeanW. Felsher
Angewandte Chemie International Edition 2009 Volume 48( Issue 41) pp:7668-7672
Publication Date(Web):
DOI:10.1002/anie.200902612
Co-reporter:Xiaoming Sun Dr.;ScottM. Tabakman;Won-Seok Seo;Li Zhang;Guangyu Zhang;Sarah Sherlock;Lu Bai
Angewandte Chemie International Edition 2009 Volume 48( Issue 5) pp:939-942
Publication Date(Web):
DOI:10.1002/anie.200805047
Co-reporter:Hailiang Wang;Xinran Wang;Xiaolin Li
Nano Research 2009 Volume 2( Issue 4) pp:336-342
Publication Date(Web):2009 April
DOI:10.1007/s12274-009-9031-x
Chemically derived and noncovalently functionalized graphene sheets (GS) were found to self-assemble onto patterned gold structures via electrostatic interactions between the functional groups and the gold surfaces. This afforded regular arrays of single graphene sheets on large substrates, which were characterized by scanning electron microscopy (SEM), Auger microscopy imaging, and Raman spectroscopy. This represents the first time that self-assembly has been used to produce on-substrate and fully-suspended graphene electrical devices. Molecular coatings on the GS were removed by high current “electrical annealing”, which restored the high electrical conductance and Dirac point of the GS. Molecular sensors for highly sensitive gas detection using the self-assembled GS devices are demonstrated.
Co-reporter:Zhuang Liu;Scott Tabakman;Kevin Welsher
Nano Research 2009 Volume 2( Issue 2) pp:85-120
Publication Date(Web):2009 February
DOI:10.1007/s12274-009-9009-8
Carbon nanotubes exhibit many unique intrinsic physical and chemical properties and have been intensively explored for biological and biomedical applications in the past few years. In this comprehensive review, we summarize the main results from our and other groups in this field and clarify that surface functionalization is critical to the behavior of carbon nanotubes in biological systems. Ultrasensitive detection of biological species with carbon nanotubes can be realized after surface passivation to inhibit the non-specific binding of biomolecules on the hydrophobic nanotube surface. Electrical nanosensors based on nanotubes provide a label-free approach to biological detection. Surface-enhanced Raman spectroscopy of carbon nanotubes opens up a method of protein microarray with detection sensitivity down to 1 fmol/L. In vitro and in vivo toxicity studies reveal that highly water soluble and serum stable nanotubes are biocompatible, nontoxic, and potentially useful for biomedical applications. In vivo biodistributions vary with the functionalization and possibly also size of nanotubes, with a tendency to accumulate in the reticuloendothelial system (RES), including the liver and spleen, after intravenous administration. If well functionalized, nanotubes may be excreted mainly through the biliary pathway in feces. Carbon nanotube-based drug delivery has shown promise in various In vitro and in vivo experiments including delivery of small interfering RNA (siRNA), paclitaxel and doxorubicin. Moreover, single-walled carbon nanotubes with various interesting intrinsic optical properties have been used as novel photoluminescence, Raman, and photoacoustic contrast agents for imaging of cells and animals. Further multidisciplinary explorations in this field may bring new opportunities in the realm of biomedicine.
Co-reporter:Xiaoming Sun Dr.;ScottM. Tabakman;Won-Seok Seo;Li Zhang;Guangyu Zhang;Sarah Sherlock;Lu Bai
Angewandte Chemie 2009 Volume 121( Issue 5) pp:957-960
Publication Date(Web):
DOI:10.1002/ange.200805047
Co-reporter:Liying Jiao,
Li Zhang,
Xinran Wang,
Georgi Diankov
&
Hongjie Dai
Nature 2009 458(7240) pp:877
Publication Date(Web):2009-04-16
DOI:10.1038/nature07919
Unlike graphene itself, or carbon nanotubes, very narrow nanoribbons of graphene are completely semiconducting. Dai and colleagues reliably produce bulk quantities of sub-10 nm graphene nanoribbons by partial encapsulation of carbon nanotubes in a polymer. The exposed part of the nanotube can be cut by plasma etching, so that the nanotube unzips when the polymer is removed, leaving a very thin strip of graphene.
Co-reporter:Xiaoming Sun;Zhuang Liu;Kevin Welsher;Joshua Tucker Robinson
Nano Research 2008 Volume 1( Issue 3) pp:203-212
Publication Date(Web):2008 September
DOI:10.1007/s12274-008-8021-8
Two-dimensional graphene offers interesting electronic, thermal, and mechanical properties that are currently being explored for advanced electronics, membranes, and composites. Here we synthesize and explore the biological applications of nano-graphene oxide (NGO), i.e., single-layer graphene oxide sheets down to a few nanometers in lateral width. We develop functionalization chemistry in order to impart solubility and compatibility of NGO in biological environments. We obtain size separated pegylated NGO sheets that are soluble in buffers and serum without agglomeration. The NGO sheets are found to be photoluminescent in the visible and infrared regions. The intrinsic photoluminescence (PL) of NGO is used for live cell imaging in the near-infrared (NIR) with little background. We found that simple physisorption via π-stacking can be used for loading doxorubicin, a widely used cancer drug onto NGO functionalized with antibody for selective killing of cancer cells in vitro. Owing to its small size, intrinsic optical properties, large specific surface area, low cost, and useful non-covalent interactions with aromatic drug molecules, NGO is a promising new material for biological and medical applications.
Co-reporter:Zhuang Liu;Corrine Davis;Weibo Cai;Lina He;Xiaoyuan Chen;
Proceedings of the National Academy of Sciences 2008 105(5) pp:1410-1415
Publication Date(Web):January 29, 2008
DOI:10.1073/pnas.0707654105
Carbon nanotubes are promising new materials for molecular delivery in biological systems. The long-term fate of nanotubes
intravenously injected into animals in vivo is currently unknown, an issue critical to potential clinical applications of these materials. Here, using the intrinsic
Raman spectroscopic signatures of single-walled carbon nanotubes (SWNTs), we measured the blood circulation of intravenously
injected SWNTs and detect SWNTs in various organs and tissues of mice ex vivo over a period of three months. Functionalization of SWNTs by branched polyethylene-glycol (PEG) chains was developed, enabling
thus far the longest SWNT blood circulation up to 1 day, relatively low uptake in the reticuloendothelial system (RES), and
near-complete clearance from the main organs in ≈2 months. Raman spectroscopy detected SWNT in the intestine, feces, kidney,
and bladder of mice, suggesting excretion and clearance of SWNTs from mice via the biliary and renal pathways. No toxic side
effect of SWNTs to mice was observed in necropsy, histology, and blood chemistry measurements. These findings pave the way
to future biomedical applications of carbon nanotubes.
Co-reporter:Xiaolin Li;Li Zhang;Xinran Wang;Sangwon Lee
Science 2008 Volume 319(Issue 5867) pp:1229-1232
Publication Date(Web):29 Feb 2008
DOI:10.1126/science.1150878
Abstract
We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase–derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical transport experiments showed that, unlike single-walled carbon nanotubes, all of the sub–10-nanometer GNRs produced were semiconductors and afforded graphene field effect transistors with on-off ratios of about 107 at room temperature.
Co-reporter:Zhuang Liu;Mark Winters Dr.;Mark Holodniy Dr.
Angewandte Chemie International Edition 2007 Volume 46(Issue 12) pp:
Publication Date(Web):9 FEB 2007
DOI:10.1002/anie.200604295
Special delivery: Functionalized single-walled nanotubes (SWNT) can be used as molecular transporters to shuttle short interfering RNA (siRNA) into human T cells and primary cells and silence the expression of HIV-specific cell-surface receptors and coreceptors (see picture; scale bars 40 μm). This silencing effect, known to block HIV viral entry and reduce infection, is superior to that observed with conventional liposome-based nonviral delivery agents.
Co-reporter:Zhuang Liu, Xiaoming Sun, Nozomi Nakayama-Ratchford, and Hongjie Dai
ACS Nano 2007 Volume 1(Issue 1) pp:50
Publication Date(Web):August 14, 2007
DOI:10.1021/nn700040t
We show that large surface areas exist for supramolecular chemistry on single-walled carbon nanotubes (SWNTs) prefunctionalized noncovalently or covalently by common surfactant or acid-oxidation routes. Water-soluble SWNTs with poly(ethylene glycol) (PEG) functionalization via these routes allow for surprisingly high degrees of π-stacking of aromatic molecules, including a cancer drug (doxorubicin) with ultrahigh loading capacity, a widely used fluorescence molecule (fluorescein), and combinations of molecules. Binding of molecules to nanotubes and their release can be controlled by varying the pH. The strength of π-stacking of aromatic molecules is dependent on nanotube diameter, leading to a method for controlling the release rate of molecules from SWNTs by using nanotube materials with suitable diameter. This work introduces the concept of “functionalization partitioning” of SWNTs, i.e., imparting multiple chemical species, such as PEG, drugs, and fluorescent tags, with different functionalities onto the surface of the same nanotube. Such chemical partitioning should open up new opportunities in chemical, biological, and medical applications of novel nanomaterials.Keywords: carbon nanotubes; doxorubicin; drug delivery; functionalization; supramolecular chemistry
Co-reporter:Zhuang Liu;Mark Winters Dr.;Mark Holodniy Dr.
Angewandte Chemie 2007 Volume 119(Issue 12) pp:
Publication Date(Web):9 FEB 2007
DOI:10.1002/ange.200604295
Sonderlieferung: Funktionalisierte einwandige Nanoröhren (SWNTs) transportieren kurze interferierende RNA (short interfering RNA, siRNA) in humane T-Zellen und Primärzellen und stoppen die Expression HIV-spezifischer Zelloberflächenrezeptoren und -corezeptoren (siehe Bild; Maßstab je 40 μm). Dieser Wirkstoff blockiert das Eindringen von HIV und verringert die Infektion stärker als übliche nichtvirale Transportsysteme auf Liposombasis.
Co-reporter:Guangyu Zhang;Pengfei Qi;Xinran Wang;Yuerui Lu;Xiaolin Li;Ryan Tu;Sarunya Bangsaruntip;David Mann;Li Zhang
Science 2006 Vol 314(5801) pp:974-977
Publication Date(Web):10 Nov 2006
DOI:10.1126/science.1133781
Abstract
Metallic and semiconducting carbon nanotubes generally coexist in as-grown materials. We present a gas-phase plasma hydrocarbonation reaction to selectively etch and gasify metallic nanotubes, retaining the semiconducting nanotubes in near-pristine form. With this process, 100% of purely semiconducting nanotubes were obtained and connected in parallel for high-current transistors. The diameter- and metallicity-dependent “dry” chemical etching approach is scalable and compatible with existing semiconductor processing for future integrated circuits.
Co-reporter:Nadine Wong Shi Kam;Zhuang Liu
Angewandte Chemie 2006 Volume 118(Issue 4) pp:
Publication Date(Web):13 DEC 2005
DOI:10.1002/ange.200503389
Endocytose oder keine Endocytose: Als Mechanismus der Internalisierung von Konjugaten einwandiger Nanoröhren in Säugerzellen wurde eine energieabhängige Endocytose über Clathrin-ausgekleidete Vertiefungen ermittelt.
Co-reporter:Nadine Wong Shi Kam, Zhuang Liu,Hongjie Dai
Angewandte Chemie International Edition 2006 45(4) pp:577-581
Publication Date(Web):
DOI:10.1002/anie.200503389
Co-reporter:Dunwei Wang;Ryan Tu;Li Zhang Dr.
Angewandte Chemie 2005 Volume 117(Issue 19) pp:
Publication Date(Web):7 APR 2005
DOI:10.1002/ange.200500291
Mehrere Durchbrüche in der Nanodrahtsynthese werden für Ge-Nanodrähte beschrieben, die durch Niedertemperatur-CVD aus Au-Nanopartikelkeimen erhalten wurden. Die optimierten Bedingungen lieferten die Nanodrähte in nahezu quantitativer Ausbeute, und das Ausrichten der Drähte in einer Strömung führte zu quasiparallelen Nanodrähten, die ihren Ursprung an genau einstellbaren Einzelpartikelpositionen haben (siehe Bilder).
Co-reporter:Dunwei Wang;Ryan Tu;Li Zhang Dr.
Angewandte Chemie International Edition 2005 Volume 44(Issue 19) pp:
Publication Date(Web):7 APR 2005
DOI:10.1002/anie.200500291
Several breakthroughs in nanowire synthesis are reported for germanium nanowires grown from gold nanoparticle seeds by a low-temperature chemical vapor deposition process. Conditions were optimized to observe the formation of nanowires in near-quantitative yields, and post-growth flow-alignment was used to obtain quasi-parallel nanowires that originate from well-controlled singleparticle sites (see images).
Co-reporter:Guangyu Zhang;David Mann;Li Zhang;Ali Javey;Yiming Li;Erhan Yenilmez;Qian Wang;James P. McVittie;Yoshio Nishi;James Gibbons
PNAS 2005 102 (45 ) pp:16141-16145
Publication Date(Web):2005-11-08
DOI:10.1073/pnas.0507064102
An oxygen-assisted hydrocarbon chemical vapor deposition method is developed to afford large-scale, highly reproducible, ultra-high-yield
growth of vertical single-walled carbon nanotubes (V-SWNTs). It is revealed that reactive hydrogen species, inevitable in
hydrocarbon-based growth, are damaging to the formation of sp2-like SWNTs in a diameter-dependent manner. The addition of oxygen scavenges H species and provides a powerful control over
the C/H ratio to favor SWNT growth. The revelation of the roles played by hydrogen and oxygen leads to a unified and universal
optimum-growth condition for SWNTs. Further, a versatile method is developed to form V-SWNT films on any substrate, lifting
a major substrate-type limitation for aligned SWNTs.
Co-reporter:Jeffrey A. Wisdom;Michael O'Connell;Nadine Wong Shi Kam
PNAS 2005 Volume 102 (Issue 33 ) pp:11600-11605
Publication Date(Web):2005-08-16
DOI:10.1073/pnas.0502680102
Biological systems are known to be highly transparent to 700- to 1,100-nm near-infrared (NIR) light. It is shown here that
the strong optical absorbance of single-walled carbon nanotubes (SWNTs) in this special spectral window, an intrinsic property
of SWNTs, can be used for optical stimulation of nanotubes inside living cells to afford multifunctional nanotube biological
transporters. For oligonucleotides transported inside living cells by nanotubes, the oligos can translocate into cell nucleus
upon endosomal rupture triggered by NIR laser pulses. Continuous NIR radiation can cause cell death because of excessive local
heating of SWNT in vitro. Selective cancer cell destruction can be achieved by functionalization of SWNT with a folate moiety, selective internalization
of SWNTs inside cells labeled with folate receptor tumor markers, and NIR-triggered cell death, without harming receptor-free
normal cells. Thus, the transporting capabilities of carbon nanotubes combined with suitable functionalization chemistry and
their intrinsic optical properties can lead to new classes of novel nanomaterials for drug delivery and cancer therapy.
Co-reporter:Hongjie Dai;Ali Javey;Pengfei Qi;Qian Wang
PNAS 2004 Volume 101 (Issue 37 ) pp:13408-13410
Publication Date(Web):2004-09-14
DOI:10.1073/pnas.0404450101
A simple method combining photolithography and shadow (or angle) evaporation is developed to fabricate single-walled carbon
nanotube (SWCNT) devices with tube lengths of ≈10–50 nm between metal contacts. Large numbers of such short devices are obtained
without the need of complex tools such as electron beam lithography. Metallic SWCNTs with lengths of ≈10 nm, near the mean
free path of l
op ≈ 15 nm for optical phonon scattering, exhibit nearly ballistic transport at high biases and can carry unprecedented 100-μA
currents per tube. Semiconducting SWCNT fieldeffect transistors with ≈50-nm channel lengths are routinely produced to achieve
quasi-ballistic operations for molecular transistors. The results demonstrate highly length-scaled and high-performance interconnects
and transistors realized with SWCNTs.
Co-reporter:Ali Javey,
Jing Guo,
Qian Wang,
Mark Lundstrom
and
Hongjie Dai
Nature 2003 424(6949) pp:654
Publication Date(Web):
DOI:10.1038/nature01797
Co-reporter:Dunwei Wang Dr.
Angewandte Chemie 2002 Volume 114(Issue 24) pp:
Publication Date(Web):12 DEC 2002
DOI:10.1002/ange.200290046
Unter Strom: Die Tieftemperaturzüchtung von Ge-Nanodrähten gelang durch chemische Abscheidung von GeH4 auf ein mit Au-Nanopartikeln beschichtetes SiO2-Substrat (siehe Bild). Diese Technik, die die Synthese von Einkristall-Nanodrähten unter mildesten Bedingungen ermöglicht, kann auch für die Strukturbildung auf vorgemusterten Substraten genutzt werden. Unter diesen Reaktionsbedingungen sollten hochwertige Nanodrähte auf einer Vielzahl von Substraten zugänglich sein, was eine breite Perspektive für nanotechnologische Ansätze bietet.
Co-reporter:Dunwei Wang Dr.
Angewandte Chemie International Edition 2002 Volume 41(Issue 24) pp:
Publication Date(Web):12 DEC 2002
DOI:10.1002/anie.200290047
Live-wire potential: Low-temperature growth of Ge nanowires has been achieved by the chemical vapor deposition of GeH4 onto a SiO2 substrate coated with Au nanoparticles (see picture). This technique, which represents the mildest growth conditions for single-crystal nanowire synthesis, can also be used for patterned growth processes. Under such conditions, the growth of high-quality nanowires on a variety of substrates is possible, which may yield many possibilities in nanotechnological applications.
Co-reporter:Yongye Liang ; Hailiang Wang ; Jigang Zhou ; Yanguang Li ; Jian Wang ; Tom Regier
Journal of the American Chemical Society () pp:
Publication Date(Web):January 23, 2012
DOI:10.1021/ja210924t
Through direct nanoparticle nucleation and growth on nitrogen doped, reduced graphene oxide sheets and cation substitution of spinel Co3O4 nanoparticles, a manganese–cobalt spinel MnCo2O4/graphene hybrid was developed as a highly efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline conditions. Electrochemical and X-ray near-edge structure (XANES) investigations revealed that the nucleation and growth method for forming inorganic–nanocarbon hybrids results in covalent coupling between spinel oxide nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge and nitrogen K-edge XANES showed strongly perturbed C–O and C–N bonding in the N-rmGO sheet, suggesting the formation of C–O–metal and C–N–metal bonds between N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge XANES suggested substitution of Co3+ sites by Mn3+, which increased the activity of the catalytic sites in the hybrid materials, further boosting the ORR activity compared with the pure cobalt oxide hybrid. The covalently bonded hybrid afforded much greater activity and durability than the physical mixture of nanoparticles and carbon materials including N-rmGO. At the same mass loading, the MnCo2O4/N-graphene hybrid can outperform Pt/C in ORR current density at medium overpotentials with stability superior to Pt/C in alkaline solutions.
Co-reporter:Hailiang Wang ; Li-Feng Cui ; Yuan Yang ; Hernan Sanchez Casalongue ; Joshua Tucker Robinson ; Yongye Liang ; Yi Cui
Journal of the American Chemical Society () pp:
Publication Date(Web):
DOI:10.1021/ja105296a
We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Selective growth of Mn3O4 nanoparticles on RGO sheets, in contrast to free particle growth in solution, allowed for the electrically insulating Mn3O4 nanoparticles to be wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ∼900 mAh/g, near their theoretical capacity, with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for a high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for the design and synthesis of battery electrodes based on highly insulating materials.
Co-reporter:Bo Zhang, Jiang Yang, Yingping Zou, Ming Gong, Hui Chen, Guosong Hong, Alexander L. Antaris, Xiaoyang Li, Chien-Liang Liu, Changxin Chen and Hongjie Dai
Chemical Science (2010-Present) 2014 - vol. 5(Issue 10) pp:NaN4075-4075
Publication Date(Web):2014/06/09
DOI:10.1039/C4SC01206B
Micro-bead based multiplexed protein immunoassays have experienced rapid growth in the past decade. Thus far, bead based protein assays have relied on the bulky 240 kDa protein phycoerythrin (PE) as the reporter dye to afford a sufficient detection signal and sensitivity, taking advantage of the 25 fluorophores in each protein. Here, we report the synthesis of gold nano-island coated glass beads (4–8 μm) through a two-step seeding-and-growth approach. We developed flow cytometric bead assays with sensitivities as low as 10 fM (∼0.2 pg ml−1) by utilizing the strong fluorescence enhancement of small molecule fluorophores (Cy-5) on the plasmonic gold (pGOLD) beads. By using different fluorescence tags to label the gold beads and varying the bead size, we obtained multiplexed plasmonic gold beads for the quantification of human cytokine IL-6, IFN-gamma, IL-1 beta, VEGF and an ovarian cancer biomarker CA-125 in biologically relevant media. The low limit of detection surpassed those of glass bead based immunoassays by 2 orders of magnitude, demonstrating the potential of plasmonic gold beads for sensitive protein biomarker quantification.
Co-reporter:Yanguang Li and Hongjie Dai
Chemical Society Reviews 2014 - vol. 43(Issue 15) pp:NaN5275-5275
Publication Date(Web):2014/06/13
DOI:10.1039/C4CS00015C
Zinc–air is a century-old battery technology but has attracted revived interest recently. With larger storage capacity at a fraction of the cost compared to lithium-ion, zinc–air batteries clearly represent one of the most viable future options to powering electric vehicles. However, some technical problems associated with them have yet to be resolved. In this review, we present the fundamentals, challenges and latest exciting advances related to zinc–air research. Detailed discussion will be organized around the individual components of the system – from zinc electrodes, electrolytes, and separators to air electrodes and oxygen electrocatalysts in sequential order for both primary and electrically/mechanically rechargeable types. The detrimental effect of CO2 on battery performance is also emphasized, and possible solutions summarized. Finally, other metal–air batteries are briefly overviewed and compared in favor of zinc–air.
Co-reporter:Yi Feng, Shoujun Zhu, Alexander L. Antaris, Hao Chen, Yuling Xiao, Xiaowei Lu, Linlin Jiang, Shuo Diao, Kuai Yu, Yan Wang, Sonia Herraiz, Jingying Yue, Xuechuan Hong, Guosong Hong, Zhen Cheng, Hongjie Dai and Aaron J. Hsueh
Chemical Science (2010-Present) 2017 - vol. 8(Issue 5) pp:NaN3711-3711
Publication Date(Web):2017/03/06
DOI:10.1039/C6SC04897H
In vivo imaging of hormone receptors provides the opportunity to visualize target tissues under hormonal control in live animals. Detecting longer-wavelength photons in the second near-infrared window (NIR-II, 1000–1700 nm) region affords reduced photon scattering in tissues accompanied by lower autofluorescence, leading to higher spatial resolution at up to centimeter tissue penetration depths. Here, we report the conjugation of a small molecular NIR-II fluorophore CH1055 to a follicle stimulating hormone (FSH-CH) for imaging ovaries and testes in live mice. After exposure to FSH-CH, specific NIR-II signals were found in cultured ovarian granulosa cells containing FSH receptors. Injection of FSH-CH allowed live imaging of ovarian follicles and testicular seminiferous tubules in female and male adult mice, respectively. Using prepubertal mice, NIR-II signals were detected in ovaries containing only preantral follicles. Resolving earlier controversies regarding the expression of FSH receptors in cultured osteoclasts, we detected for the first time specific FSH receptor signals in bones in vivo. The present imaging of FSH receptors in live animals using a ligand-conjugated NIR-II fluorophore with low cell toxicity and rapid clearance allows the development of non-invasive molecular imaging of diverse hormonal target cells in vivo.
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