Co-reporter:Jin Sun, Chunxiao Lv, Fan Lv, Shuai Chen, Daohao Li, Ziqi Guo, Wei Han, Dongjiang Yang, and Shaojun Guo
ACS Nano June 27, 2017 Volume 11(Issue 6) pp:6186-6186
Publication Date(Web):May 15, 2017
DOI:10.1021/acsnano.7b02275
Searching the long-life transition-metal oxide (TMO)-based materials for future lithium-ion batteries (LIBs) is still a great challenge because of the mechanical strain resulting from volume change of TMO anodes during the lithiation/delithiation process. To well address this challenging issue, we demonstrate a controlled method for making the multishelled TMO hollow microfibers with tunable shell numbers to achieve the optimal void for efficient lithium-ion storage. Such a particularly designed void can lead to a short diffusion distance for fast diffusion of Li+ ions and also withstand a large volume variation upon cycling, both of which are the key for high-performance LIBs. Triple-shelled TMO hollow microfibers are a quite stable anode material for LIBs with high reversible capacities (NiO: 698.1 mA h g–1 at 1 A g–1; Co3O4: 940.2 mA h g–1 at 1 A g–1; Fe2O3: 997.8 mA h g–1 at 1 A g–1), excellent rate capability, and stability. The present work opens a way for rational design of the void of multiple shells in achieving the stable lithium-ion storage through the biomass conversion strategy.Keywords: lithium-ion batteries; multishelled fiber; seaweed; transition-metal oxides; tunable shell numbers;
Co-reporter:Shuo Zhang;Daohao Li;Shuai Chen;Xianfeng Yang;Xiaoliang Zhao;Quansheng Zhao;Sridhar Komarneni
Journal of Materials Chemistry A 2017 vol. 5(Issue 24) pp:12453-12461
Publication Date(Web):2017/06/20
DOI:10.1039/C7TA03070C
Co9S8 has received intensive attention as an electrode material for electrical energy storage (EES) systems due to its unique structural features and rich electrochemical properties. However, the instability and inferior rate capability of the Co9S8 electrode material during the charge/discharge process has restricted its applications in supercapacitors (SCs). Here, MOF-derived Co9S8 nanoparticles (NPs) embedded in carbon co-doped with N and S (Co9S8/NS–C) were synthesized as a high rate capability and super stable electrode material for SCs. The Co9S8/NS–C material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the Co9S8/NS–C material possessed a unique nanostructure in which Co9S8 NPs were encapsulated in porous graphitic carbon co-doped with N and S. The N/S co-doped porous graphitic carbon of composite led to improved rate performance by enhancing the stability of the electrode material and shortening the ion diffusion paths due to a synergistic effect. The as-prepared Co9S8/NS–C-1.5 h material exhibited a high specific capacitance of 734 F g−1 at a current density of 1 A g−1, excellent rate capability (653 F g−1 at 10 A g−1) and superior cycling stability, i.e., capacitance retention of about 99.8% after 140 000 cycles at a current density of 10 A g−1. Thus, a new approach to fabricate promising electrode materials for high-performance SCs is presented here.
Co-reporter:Shuo Zhang;Daohao Li;Shuai Chen;Xianfeng Yang;Xiaoliang Zhao;Quansheng Zhao;Sridhar Komarneni
Journal of Materials Chemistry A 2017 vol. 5(Issue 24) pp:12453-12461
Publication Date(Web):2017/06/20
DOI:10.1039/C7TA03070C
Co9S8 has received intensive attention as an electrode material for electrical energy storage (EES) systems due to its unique structural features and rich electrochemical properties. However, the instability and inferior rate capability of the Co9S8 electrode material during the charge/discharge process has restricted its applications in supercapacitors (SCs). Here, MOF-derived Co9S8 nanoparticles (NPs) embedded in carbon co-doped with N and S (Co9S8/NS–C) were synthesized as a high rate capability and super stable electrode material for SCs. The Co9S8/NS–C material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the Co9S8/NS–C material possessed a unique nanostructure in which Co9S8 NPs were encapsulated in porous graphitic carbon co-doped with N and S. The N/S co-doped porous graphitic carbon of composite led to improved rate performance by enhancing the stability of the electrode material and shortening the ion diffusion paths due to a synergistic effect. The as-prepared Co9S8/NS–C-1.5 h material exhibited a high specific capacitance of 734 F g−1 at a current density of 1 A g−1, excellent rate capability (653 F g−1 at 10 A g−1) and superior cycling stability, i.e., capacitance retention of about 99.8% after 140 000 cycles at a current density of 10 A g−1. Thus, a new approach to fabricate promising electrode materials for high-performance SCs is presented here.
Co-reporter:Yukun Zhu;Jun Ren;Xianfeng Yang;Guojing Chang;Yuyu Bu;Guodong Wei;Wei Han
Journal of Materials Chemistry A 2017 vol. 5(Issue 20) pp:9952-9959
Publication Date(Web):2017/05/23
DOI:10.1039/C7TA02179H
Photoelectrochemical water oxidation driven by photocatalysts is one of the most effective ways for converting solar energy into fuels and chemicals. However, to date, the solar conversion efficiency using the established photocatalysts is still low. Herein, we report a new strategy for making a class of three-dimensional (3D) BiVO4/Fe-based (Ni1−xFex and Co1−xFex) layered double hydroxide (LDH) interface heterostructures for boosting the photoelectrocatalytic water oxidation performance. Compared with the BiVO4, the BiVO4/Ni0.5Fe0.5–LDH interface photoanode exhibits about 4-fold photocurrent enhancement at 1.23 V vs. the reversible hydrogen electrode and remarkable negative shift (320 mV) of the onset potential for the oxygen evolution reaction (OER). Theoretical calculations reveal that the enhanced photocatalysis for the OER is mainly attributed to the optimal light absorption and the acceleration of electron–hole separation enabled by the strong electronic coupling at the BiVO4/NiFe–LDH interface. The present work first highlights the importance of tuning the light absorption and the separation of carriers using interface engineering in enhancing the solar photocatalytic performance.
Co-reporter:Jianjiang Li;Shuai Chen;Xiaoyi Zhu;Xilin She;Tongchao Liu;Huawei Zhang;Sridhar Komarneni;Xiangdong Yao
Advanced Science 2017 Volume 4(Issue 12) pp:
Publication Date(Web):2017/12/01
DOI:10.1002/advs.201700345
AbstractA biomass-templated pathway is developed for scalable synthesis of NiCo2O4@carbon aerogel electrodes for supercapacitors, where NiCo2O4 hollow nanoparticles with an average outer diameter of 30–40 nm are conjoined by graphitic carbon forming a 3D aerogel structure. This kind of NiCo2O4 aerogel structure shows large specific surface area (167.8 m2 g−1), high specific capacitance (903.2 F g−1 at a current density of 1 A g−1), outstanding rate performance (96.2% capacity retention from 1 to 10 A g−1), and excellent cycling stability (nearly without capacitance loss after 3000 cycles at 10 A g−1). The unique structure of the 3D hollow aerogel synergistically contributes to the high performance. For instance, the 3D interconnected porous structure of the aerogel is beneficial for electrolyte ion diffusion and for shortening the electron transport pathways, and thus can improve the rate performance. The conductive carbon joint greatly enhances the specific capacity, and the hollow structure prohibits the volume changes during the charge–discharge process to significantly improve the cycling stability. This work represents a giant step toward the preparation of high-performance commercial supercapacitors.
Co-reporter:Xin Sun, Xiaoyi Zhu, Xianfeng Yang, Jin Sun, ... Dongjiang Yang
Green Energy & Environment 2017 Volume 2, Issue 2(Volume 2, Issue 2) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.gee.2017.01.008
High-performance lithium ion batteries (LIBs) require electrode material to have an ideal electrode construction which provides fast ion transport, short solid-state ion diffusion, large surface area, and high electric conductivity. Herein, highly porous three-dimensional (3D) aerogels composed of cobalt ferrite (CoFe2O4, CFO) nanoparticles (NPs) and carbon nanotubes (CNTs) are prepared using sustainable alginate as the precursor. The key feature of this work is that by using the characteristic egg-box structure of the alginate, metal cations such as Co2+ and Fe3+ can be easily chelated via an ion-exchange process, thus binary CFO are expected to be prepared. In the hybrid aerogels, CFO NPs interconnected by the CNTs are embedded in carbon aerogel matrix, forming the 3D network which can provide high surface area, buffer the volume expansion and offer efficient ion and electron transport pathways for achieving high performance LIBs. The as-prepared hybrid aerogels with the optimum CNT content (20 wt%) delivers excellent electrochemical properties, i.e., reversible capacity of 1033 mAh g−1 at 0.1 A g−1 and a high specific capacity of 874 mAh g−1 after 160 cycles at 1 A g−1. This work provides a facile and low cost route to fabricate high performance anodes for LIBs.CFO NPs interconnected by the CNTs are embedded in carbon aerogel matrix to form a 3D network which can provide high surface area, buffer the volume expansion and offer efficient ion and electron transport pathways for achieving high performance LIBs.Download high-res image (169KB)Download full-size image
Co-reporter:Long Liu;Huilin Hou;Lin Wang;Rui Xu;Yong Lei;Shaohua Shen;Weiyou Yang
Nanoscale (2009-Present) 2017 vol. 9(Issue 40) pp:15650-15657
Publication Date(Web):2017/10/19
DOI:10.1039/C7NR05658C
In the present work, we report the exploration of a transparent CdS@TiO2 nanotextile photoanode with boosted photoelectrocatalytic (PEC) efficiency and stability, by the controllable coating of an amorphous TiO2 ultrathin layer via the atomic layer deposition (ALD) technique. The optimal CdS@TiO2 nanotextile photoanode with a 3.5 nm TiO2 ultrathin layer exhibits a photocurrent density of 1.8 mA cm−2 at 0 V vs. RHE, which is 11 times higher than that of the pristine CdS counterpart. The photocatalytic H2 evolution rate of CdS@TiO2 ranges up to 47.5 mmol g−1 h−1, which is superior to those reported for one-dimensional CdS-based counterparts. Moreover, the photocurrent of CdS@TiO2 nanotextile photoanodes shows only 9% decay after 9 h, suggesting its profoundly enhanced PEC stability, in comparison with that of pristine CdS photoanodes (almost down to zero after 3 hours). It is verified that the introduced TiO2 nanoshells could limit the charge recombination, facilitate the charge separation, reduce the charge transfer resistance, and enhance the wettability of the electrodes, resulting in their significantly enhanced PEC performance.
Co-reporter:Guichao Ye;Xiaoyi Zhu;Shuai Chen;Daohao Li;Yafang Yin;Yun Lu;Sridhar Komarneni
Journal of Materials Chemistry A 2017 vol. 5(Issue 18) pp:8247-8254
Publication Date(Web):2017/05/10
DOI:10.1039/C7TA02334K
We developed a unique industrial-scale sustainable biomass conversion strategy for the synthesis of multifunctional, three-dimensional (3D) carbon nanofiber (CNF) aerogels with hierarchical porosity. The above aerogels were also highly nitrogen-doped through pyrolysis of bamboo cellulose. The important and critical part of our synthesis strategy was to assemble the nanofibers of cellulose (NFC) from bamboo to make aerogels of controlled porosity with a hierarchical porous structure. The as-prepared CNF aerogels with abundant chemical reaction sites and three-dimensional electron and ion transport pathways were found to be new high-performance anode materials for lithium-ion batteries (LIBs). In particular, the N-doped CNF aerogel prepared with 1 D fibers of 50 nm in diameter as building-blocks exhibited a high reversible capacity of 630.7 mA h g−1 at 1 A g−1, excellent rate capability (289 mA h g−1 at 20 A g−1) and excellent cycling performance (651 mA h g−1 at 1 A g−1 after 1000 cycles) in LIBs.
Co-reporter:Na Ma, Yi (Alec) Jia, Xianfeng Yang, Xilin She, Longzhou Zhang, Zhi Peng, Xiangdong Yao and Dongjiang Yang
Journal of Materials Chemistry A 2016 vol. 4(Issue 17) pp:6376-6384
Publication Date(Web):21 Mar 2016
DOI:10.1039/C6TA00591H
Developing earth-abundant, active and stable electrocatalysts which operate in two-electrode rechargeable metal–air batteries, including both oxygen evolution and reduction reactions (OER and ORR), is vital for renewable energy conversion in real application. Here, we demonstrate a three-dimensional (3D) bifunctional nanoaerogel electrocatalyst that exhibits good electrocatalytic properties for both OER and ORR. This material was fabricated using a scalable and facile method involving the pyrolysis of (Ni,Co)/CNT alginate hydrogels derived from sustainable seaweed biomass after an ion exchange process. The bifunctionality for oxygen electrocatalysis as shown by the OER–ORR potential difference (ΔE, the OER and ORR potentials are taken at the current densities of 10 mA cm−2 and −3 mA cm−2 in 0.1 M KOH, respectively) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts. The good performance was attributed to the ternary Ni/NiO/NiCo2O4 catalytic center for charge transfer and 3D hierarchical mesoporous hybrid framework for efficient mass transport. More importantly, the Zn–air battery fabricated with the hybrid nanoaerogel as a bifunctional electrocatalyst displays very high energy efficiency (58.5%) and long-term stability. Prospectively, our present work may pave a new way to develop earth-abundant and low cost high-performance bifunctional electrocatalysts for rechargeable metal–air batteries.
Co-reporter:Long Liu, Xianfeng Yang, Chunxiao Lv, Aimei Zhu, Xiaoyi Zhu, Shaojun Guo, Chengmeng Chen, and Dongjiang Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 11) pp:7047
Publication Date(Web):March 4, 2016
DOI:10.1021/acsami.5b12427
We developed a nanoscale Kirkendall effect assisted method for simple and scalable synthesis of three-dimensional (3D) Fe2O3 hollow nanoparticles (NPs)/graphene aerogel through the use of waste seaweed biomass as new precursors. The Fe2O3 hollow nanoparticles with an average shell thickness of ∼6 nm are distributed on 3D graphene aerogel, and also act as spacers to make the separation of the neighboring graphene nanosheets. The graphene–Fe2O3 aerogels exhibit high rate capability (550 mA h g–1 at 5 A g –1) and excellent cyclic stability (729 mA h g–1 at 0.1 A g–1 for 300 cycles), outperforming all of the reported Fe2O3/graphene hybrid electrodes, due to the hollow structure of the active Fe2O3 NPs and the unique structure of the 3D graphene aerogel framework. The present work represents an important step toward high-level control of high-performance 3D graphene–Fe-based NPs aerogels for maximizing lithium storage with new horizons for important fundamental and technological applications.Keywords: egg box; hollow nanoparticles; Kirkendall effect; lithium ion batteries; seaweed
Co-reporter:Xilin She, Qianqian Li, Na Ma, Jin Sun, Dengwei Jing, Chengmeng Chen, Lijun Yang, and Dongjiang Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 16) pp:10383
Publication Date(Web):April 14, 2016
DOI:10.1021/acsami.6b03260
High-performance nitrogen and germanium codoped carbon nanotubes (N–Ge–CNTs) were synthesized as oxygen reduction reaction (ORR) catalysts by one-step sintering of carboxyethyl germanium sesquioxide and multiwalled CNTs in NH3 atmosphere. The ORR electrocatalytic activity evaluation was performed by using limited current density, selective reaction pathway, onset potential, H2O2 yields, and kinetic current density. In comparison with Ge or N solely doped CNTs, the codoped samples display more excellent ORR catalytic performance. It was observed that the codoped GeN3C, GeN4, and GeN4 + NC3 microstructures in N–Ge–CNTs are crucial to improving ORR catalytic performance, such as ideal 4 electron pathway (3.95) and positive onset potential (−0.08 V). The high ORR performance is attributed to the synergistic effect of N and Ge doping, which is capable of activating the π electrons of sp2 hybridized orbital around carbon nantotubes. The ORR catalytic synergistic effect has also been verified by calculating the work function on the basis of density functional theory (DFT).Keywords: carbon nanotubes; Ge/N codoping; oxygen reduction reaction; synergistic effect
Co-reporter:Xiaoyi Zhu, Xianfeng Yang, Chunxiao Lv, Shaojun Guo, Jianjiang Li, Zhanfeng Zheng, Huaiyong Zhu, and Dongjiang Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 29) pp:18815-18821
Publication Date(Web):July 6, 2016
DOI:10.1021/acsami.6b04588
To achieve uniform carbon coating on TiO2 nanomaterials, high temperature (>500 °C) annealing treatment is a necessity. However, the annealing treatment inevitably leads to the strong phase transformation from TiO2(B) with high lithium ion storage (LIS) capacity to anatase with low LIS one as well as the damage of nanostructures. Herein, we demonstrate a new approach to create TiO2(B)/carbon core/shell nanotubes (C@TBNTs) using a long-chain silane polymethylhydrosiloxane (PMHS) to bind the TBNTs by forming Si–O–Ti bonds. The key feature of this work is that the introduction of PMHS onto TBNTs can afford TBNTs with very high thermal stability at higher than 700 °C and inhibit the phase transformation from TiO2(B) to anatase. Such a high thermal property of PMHS-TBNTs makes them easily coated with highly graphitic carbon shell via CVD process at 700 °C. The as-prepared C@TBNTs deliver outstanding rate capability and electrochemical stability, i.e., reversible capacity above 250 mAh g–1 at 10 C and a high specific capacity of 479.2 mAh g–1 after 1000 cycles at 1 C. As far as we know, the LIS performance of our sample is the highest among the previously reported TiO2(B) anode materials.
Co-reporter:Yun Lu, Hongwei Liu, Runan Gao, Shaoliang Xiao, Ming Zhang, Yafang Yin, Siqun Wang, Jian Li, and Dongjiang Yang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 42) pp:29179
Publication Date(Web):October 6, 2016
DOI:10.1021/acsami.6b10749
Nanofibrillated cellulose (NFC) has received increasing attention in science and technology because of not only the availability of large amounts of cellulose in nature but also its unique structural and physical features. These high-aspect-ratio nanofibers have potential applications in water remediation and as a reinforcing scaffold in composites, coatings, and porous materials because of their fascinating properties. In this work, highly porous NFC aerogels were prepared based on tert-butanol freeze-drying of ultrasonically isolated bamboo NFC with 20–80 nm diameters. Then nonagglomerated 2–20-nm-diameter silver oxide (Ag2O) nanoparticles (NPs) were grown firmly onto the NFC scaffold with a high loading content of ∼500 wt % to fabricate Ag2O@NFC organic–inorganic composite aerogels (Ag2O@NFC). For the first time, the coherent interface and interaction mechanism between the cellulose Iβ nanofiber and Ag2O NPs are explored by high-resolution transmission electron microscopy and 3D electron tomography. Specifically, a strong hydrogen between Ag2O and NFC makes them grow together firmly along a coherent interface, where good lattice matching between specific crystal planes of Ag2O and NFC results in very small interfacial straining. The resulting Ag2O@NFC aerogels take full advantage of the properties of the 3D organic aerogel framework and inorganic NPs, such as large surface area, interconnected porous structures, and supreme mechanical properties. They open up a wide horizon for functional practical usage, for example, as a flexible superefficient adsorbent to capture I– ions from contaminated water and trap I2 vapor for safe disposal, as presented in this work. The viable binding mode between many types of inorganic NPs and organic NFC established here highlights new ways to investigate cellulose-based functional nanocomposites.Keywords: aerogel; Ag2O nanocrystals; coherent interface; iodine capture; nanofibrillated cellulose
Co-reporter:Rui Wang, Xuyan Xue, Wencai Lu, Hongwei Liu, Chao Lai, Kai Xi, Yanke Che, Jingquan Liu, Shaojun Guo and Dongjiang Yang
Nanoscale 2015 vol. 7(Issue 30) pp:12833-12838
Publication Date(Web):03 Jul 2015
DOI:10.1039/C5NR02582F
We demonstrate that mixed-phase anatase–TiO2(B) nanoparticles can provide an interesting interphase interface with atomic-level contact for achieving more efficient Li ion storage with high capacity and cycle life. A novel lithium storage mode – “interfacial charge storage in allomorphs” (ICSA) – plays an important role in enhancing Li ion storage.
Co-reporter:Chunxiao Lv, Xianfeng Yang, Ahmad Umar, Yanzhi Xia, Yi(Alec) Jia, Lu Shang, Tierui Zhang and Dongjiang Yang
Journal of Materials Chemistry A 2015 vol. 3(Issue 45) pp:22708-22715
Publication Date(Web):21 Sep 2015
DOI:10.1039/C5TA06393K
The increasing demand for high performance lithium ion batteries (LIBs) has aroused great interest in developing high specific capacity, cycle performance and rate capability anode materials. Transition metal oxides (TMOs) have attracted much attention as promising anode materials for rechargeable LIBs owing to their high theoretical capacity. Here, a general strategy has been developed to fabricate high-performance fibrous TMO anodes such as elemental Ni doped NiO fibre (NiO/Ni/C-F), yolk–shell structured carbon@Fe2O3 fibre (C@Fe2O3-F), and hollow CuO fibre (CuO-HF) with controllable nanostructures by using alginate microfibres as templates. The key to the formation of various TMO micro-/nano-structures is the templating ability of the natural structure of long alginate molecular chains, where the metal cations can be confined in an “egg-box” via coordination with negatively charged α-L-guluronate blocks. When tested as anode materials for LIB half cells, these fibrous electrodes deliver excellent cycling performance with no capacity decrease after 200 cycles (793 mA h g−1, NiO/Ni/C-F, 0.072 A g−1; 1035 mA h g−1, C@Fe2O3-F, 0.1 A g−1; 670 mA h g−1, CuO-HF, 0.067 A g−1), and demonstrate great rate performance at different current densities. This finding highlights a general, green and eco-friendly strategy for the scale-up production of potential high-performance TMO anodes for LIBs.
Co-reporter:Wei Zhao, Pei Yuan, Xilin She, Yanzhi Xia, Sridhar Komarneni, Kai Xi, Yanke Che, Xiangdong Yao and Dongjiang Yang
Journal of Materials Chemistry A 2015 vol. 3(Issue 27) pp:14188-14194
Publication Date(Web):19 Jun 2015
DOI:10.1039/C5TA03199K
A high-performance one-dimensional (1D) nanofibrillar N–Co–C oxygen reduction reaction (ORR) catalyst was fabricated via electrospinning using renewable natural alginate and multiwalled carbon nanotubes (MWCNTs) as precursors, where Co nanoparticles (NPs) are encapsulated by nitrogen (N)-doped amorphous carbon and assembled on MWCNTs. The 1D morphology not only prevents the aggregation of the Co NPs, but also provides a typical multimodal mesoporous structure which is beneficial for the O2 diffusion and the migration of adsorbed superoxide. In combination with the high conductivity of CNTs, the N-doped amorphous carbon shell can exert electron release on the encapsulated Co NPs, and thus enhance the ORR activity. It is also a protective layer that stabilizes the Co NPs, which ensures a high ORR activity of the catalysts in both alkaline and acid media and long-term durability. So compared with a commercial Pt/C catalyst, as expected, the N–Co–C nanofiber reported herein exhibited a comparable current density and onset potential (−0.06 V), with better durability in alkaline and acid solutions and better resistance to crossover effects in the ORR.
Co-reporter:Jin Sun, Long Liu, Xiaoliang Zhao, Shuanglei Yang, Sridhar Komarneni and Dongjiang Yang
RSC Advances 2015 vol. 5(Issue 92) pp:75354-75359
Publication Date(Web):01 Sep 2015
DOI:10.1039/C5RA10907H
Niobates with one-dimensional (1D) morphology, layered KNb3O8 nanorods and tunnel structured Na2Nb2O6·H2O nanofibers, are fabricated readily by a reaction between niobium oxide and alkali hydroxides under hydrothermal conditions. They exhibit ideal properties for removal of radioactive cations such as Sr2+, Ba2+ (as simulant for 226Ra2+) and Cs+ ions from wastewater through an ion exchange process. Compared with the Na2Nb2O6·H2O nanofibers, the KNb3O8 nanorods displayed better performance for the irreversible entrapment of the toxic cations, particularly Ba2+ cations, due to the deformation of the layer structure. Besides, these 1D niobates are acid resistant with selective uptake of the radioactive cations in the presence of a large excess of K+ or Na+ ions.
Co-reporter:Rui Wang, Qingduan Wu, Yun Lu, Hongwei Liu, Yanzhi Xia, Jingquan Liu, Dongjiang Yang, Ziyang Huo, and Xiangdong Yao
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 3) pp:2118
Publication Date(Web):January 10, 2014
DOI:10.1021/am405231p
The preparation of nitrogen-doped TiO2/graphene nanohybrids and their application as counter electrode for dye-sensitized solar cell (DSSC) are presented. These nanohybrids are prepared by self-assembly of pyrene modified H2Ti3O7 nanosheets and graphene in aqueous medium via π–π stacking interactions, followed by thermal calcination at different temperatures in ammonia atmosphere to afford nitrogen-doped TiO2/graphene nanohybrids. H2Ti3O7 nanosheets were synthesized from TiOSO4·xH2O by a hydrothermal reaction at 150 °C for 48 h. The microstructure of the obtained mixed-phase nanohybrids was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transforms infrared spectroscopy (FTIR). Moreover, the performances of the as-prepared nanohybrids as counter electrode materials for DSSC was investigated, and the results indicated that the nanohybrids prepared at higher nitridation temperature would lead to higher short-circuit current density than those prepared at lower nitridation temperature, indicating that it can be utilized as a low-cost alternative to Pt for DSSCs and other applications.Keywords: counter electrode; dye-sensitized solar cells; graphene; graphene nanohybrids; nitrogen-doped TiO2; π−π stacking;
Co-reporter:Long Liu, Wei Liu, Xiaoliang Zhao, Daimei Chen, Rongsheng Cai, Weiyou Yang, Sridhar Komarneni, and Dongjiang Yang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 18) pp:16082
Publication Date(Web):August 29, 2014
DOI:10.1021/am504000n
Radioactive iodine isotopes that are produced in nuclear power plants and used in medical research institutes could be a serious threat to the health of many people if accidentally released to the environment because the thyroid gland can absorb and concentrate them from a liquid. For this reason, uptake of iodide anions was investigated on microrosette-like δ-Bi2O3 (MR-δ-Bi2O3). The MR-δ-Bi2O3 adsorbent showed a very high uptake capacity of 1.44 mmol g–1 by forming insoluble Bi4I2O5 phase. The MR-δ-Bi2O3 also displayed fast uptake kinetics and could be easily separated from a liquid after use because of its novel morphology. In addition, the adsorbent showed excellent selectivity for I– anions in the presence of large concentrations of competitive anions such as Cl– and CO32–, and could work in a wide pH range of 4–11. This study led to a new and highly efficient Bi-based adsorbent for iodide capture from solutions.Keywords: adsorbent; Bi4I2O5; iodide uptake; radioactive waste; selectivity; δ-Bi2O3
Co-reporter:Shuchao Zhang;Dengwei Jing;Hongwei Liu;Long Liu;Yi Jia
Nano Research 2014 Volume 7( Issue 11) pp:1659-1669
Publication Date(Web):2014 November
DOI:10.1007/s12274-014-0526-8
Photodynamic therapy (PDT), which is a procedure that uses photosensitizing drug to apply therapy selectively to target sites, has been proven to be a safe treatment for cancers and conditions that may develop into cancers. Nano-sized TiO2 has been regarded as potential photosensitizer for UV light driven PDT. In this study, four types of TiO2 nanofibers were prepared from proton tri-titanate (H2T3O7) nanofiber. The as-obtained nanofibers were demonstrated as efficient photosensitizers for PDT killing of HeLa cells. MTT assay and flow cytometry (FCM) were carried out to evaluate the biocompatibility, percentage of apoptotic cells, and cell viability. The non-cytotoxicity of the as-prepared TiO2 nanofibers in the absence of UV irradiation has also been demonstrated. Under UV light irradiation, the TiO2 nanofibers, particularly the mixed phase nanofibers, displayed much higher cell-killing efficiency than Pirarubicin (THP), which is a common drug to induce the apoptosis of HeLa cells. We ascribe the high cellkilling efficiency of the mixed phase nanofibers to the bandgap edge match and stable interface between TiO2(B) and anatase phases in a single nanofiber, which can inhibit the recombination of the photogenerated electrons and holes. This promotes the charge separation and transfer processes and can produce more reactive oxygen species (ROS) that are responsible for the killing of HeLa cells.
Co-reporter:Jizhen Zhang;Aihua Li;Huihui Liu;Jingquan Liu
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 19) pp:2715-2724
Publication Date(Web):
DOI:10.1002/pola.27288
ABSTRACT
A recyclable solid-state photoinitiator based on the surface modified niobium hydroxide is prepared and successfully introduces into reversible addition–fragmentation chain transfer (RAFT) polymerization under visible light illumination. It is revealed by gel permeation chromatography analysis that well-defined polymers with controlled molecular weight and narrow polydispersity index can be achieved when the feed ratio of photoinitiator to the RAFT agent was controlled properly. It is also found that the polymerization is highly responsive to external stimulus and when light is removed from the system polymerization stops almost immediately. In addition, the photoinitiator can be recycled and reused to initiate the polymerization for many times without significant decrease of initiation efficiency. At last, the mechanism for the light initiated polymerization is proposed to illuminate how the initiation and chain propagation proceed. This facile, green and visible light initiation methodology could attract more and more applications in polymer science with the depletion of fossil energy.
A recyclable solid-state photoinitiator based on the surface modified niobium hydroxide was prepared and successfully introduced into reversible addition–fragmentation chain transfer (RAFT) polymerization under visible light illumination. It is revealed that well-defined polymers with controlled molecular weight and narrow polydispersity index (PDI) can be achieved when the feed ratio of photoinitiator to the RAFT agent was controlled properly. It is also found that the polymerization is highly responsive to light initiation. In addition, the photoinitiator can be recycled and reused to initiate the polymerization for many times without significant decrease of initiation efficiency. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2715–2724
Co-reporter:Yun Lu, Qingfeng Sun, Xilin She, Yanzhi Xia, Yixing Liu, Jian Li, Dongjiang Yang
Carbohydrate Polymers 2013 Volume 98(Issue 2) pp:1497-1504
Publication Date(Web):6 November 2013
DOI:10.1016/j.carbpol.2013.07.038
•α-Chitin nanofibers (∼20 nm) from prawn shell were fabricated via pulsed ultrasonic treatment (60 KHz, 300 W, pH = 7).•We made highly transparent film (transmittance achieved 90.2% at 600 nm) and flexible ultralight foam using α-chitin nanofibers.•This paper provides ultrasonication as a new way to fabricate ultralong nanofibers from natural polysaccharide materials.α-Chitin nanofibers were fabricated with dried shrimp shells via a simple high-intensity ultrasonic treatment under neutral conditions (60 KHz, 300 W, pH = 7). The diameter of the obtained chitin nanofibers could be controlled within 20–200 nm by simply adjusting the ultrasonication time. The pulsed ultrasound disassembled natural chitin into high-aspect-ratio nanofibers with a uniform width (19.4 nm after 30 min sonication). The EDS, FTIR, and XRD characterisation results verified that α-chitin crystalline structure and molecular structure were maintained after the chemical purification and ultrasonic treatments. Interestingly, ultrasonication can slightly increase the degree of crystallinity of chitin (from 60.1 to 65.8). Furthermore, highly transparent chitin films (the transmittance was 90.2% at a 600 nm) and flexible ultralight chitin foams were prepared from chitin nanofiber hydrogels.
Co-reporter:Xilin She, Tongchao Liu, Nan Wu, Xijin Xu, Jianjiang Li, Dongjiang Yang, Ray Frost
Materials Chemistry and Physics 2013 Volume 143(Issue 1) pp:240-246
Publication Date(Web):16 December 2013
DOI:10.1016/j.matchemphys.2013.08.059
•Spectrum analysis on the reduction degree of GO reduced by different methods.•Determine the optimized reduction conditions of GO and polymer/r-GO composites.•The two-step reduction is more effective than one-step reduction.In this paper, the reduction degree of graphene oxide (GO) reduced using chemical reduction and thermal reduction methods was characterized by spectrum analysis. The optimized conditions of reducing GO were determined that the hydrazine hydrate is the best reducing agent and the appropriate thermal reduction temperature is at 240 °C. The obtained GO solution was mixed with polystyrene (PS) solution to prepare PS/r-GO composites by using two-step reduction technique under the optimized conditions. The structure and micro-morphology of GO, r-GO and PS/r-GO composites were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) respectively. It is also observed that the two-step reduction pathway is more effective than one-step reduction for improving the reduction degree of GO. Accordingly, the electric conductivity of PS/r-GO composites prepared by two-step reduction technique is as high as 21.45 S m−1, which is much higher than that of composites fabricated by one-step reduction method. The spectrum techniques will highlight new opportunities for investigating the reduction degree of GO in polymer composites.
Co-reporter: Dongjiang Yang;Dr. Jian Zhao;Dr. Hongwei Liu;Dr. Zhanfeng Zheng;Dr. Moses O. Adebajo;Dr. Hongxia Wang; Xiaotang Liu; Hongjie Zhang; Jin-cai Zhao; John Bell; Huaiyong Zhu
Chemistry - A European Journal 2013 Volume 19( Issue 16) pp:5113-5119
Publication Date(Web):
DOI:10.1002/chem.201202719
Abstract
Cerium ions (Ce3+) can be selectively doped into the TiO2(B) core of TiO2(B)/anatase core–shell nanofibers by means of a simple one-pot hydrothermal treatment of a starting material of hydrogen trititanate (H2Ti3O7) nanofibers. These Ce3+ ions (≈0.202 nm) are located on the (110) lattice planes of the TiO2(B) core in tunnels (width≈0.297 nm). The introduction of Ce3+ ions reduces the defects of the TiO2(B) core by inhibiting the faster growth of (110) lattice planes. More importantly, the redox potential of the Ce3+/Ce4+ couple (E°(Ce3+/Ce4+)=1.715 V versus the normal hydrogen electrode) is more negative than the valence band of TiO2(B). Therefore, once the Ce3+-doped nanofibers are irradiated by UV light, the doped Ce3+ ions—in close vicinity to the interface between the TiO2(B) core and anatase nanoshell—can efficiently trap the photogenerated holes. This facilitates the migration of holes from the anatase shell and leaves more photogenerated electrons in the anatase nanoshell, which results in a highly efficient separation of photogenerated charges in the anatase nanoshell. Hence, this enhanced charge-separation mechanism accelerates dye degradation and alcohol oxidation processes. The one-pot treatment doping strategy is also used to selectively dope other metal ions with variable oxidation states such as Co2+/3+ and Cu+/2+ ions. The doping substantially improves the photocatalytic activity of the mixed-phase nanofibers. In contrast, the doping of ions with an invariable oxidation state, such as Zn2+, Ca2+, or Mg2+, does not enhance the photoactivity of the mixed-phase nanofibers as the ions could not trap the photogenerated holes.
Co-reporter:Yukun Zhu, Jun Ren, Xianfeng Yang, Guojing Chang, Yuyu Bu, Guodong Wei, Wei Han and Dongjiang Yang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 20) pp:NaN9959-9959
Publication Date(Web):2017/05/03
DOI:10.1039/C7TA02179H
Photoelectrochemical water oxidation driven by photocatalysts is one of the most effective ways for converting solar energy into fuels and chemicals. However, to date, the solar conversion efficiency using the established photocatalysts is still low. Herein, we report a new strategy for making a class of three-dimensional (3D) BiVO4/Fe-based (Ni1−xFex and Co1−xFex) layered double hydroxide (LDH) interface heterostructures for boosting the photoelectrocatalytic water oxidation performance. Compared with the BiVO4, the BiVO4/Ni0.5Fe0.5–LDH interface photoanode exhibits about 4-fold photocurrent enhancement at 1.23 V vs. the reversible hydrogen electrode and remarkable negative shift (320 mV) of the onset potential for the oxygen evolution reaction (OER). Theoretical calculations reveal that the enhanced photocatalysis for the OER is mainly attributed to the optimal light absorption and the acceleration of electron–hole separation enabled by the strong electronic coupling at the BiVO4/NiFe–LDH interface. The present work first highlights the importance of tuning the light absorption and the separation of carriers using interface engineering in enhancing the solar photocatalytic performance.
Co-reporter:Shuo Zhang, Daohao Li, Shuai Chen, Xianfeng Yang, Xiaoliang Zhao, Quansheng Zhao, Sridhar Komarneni and Dongjiang Yang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 24) pp:NaN12461-12461
Publication Date(Web):2017/05/12
DOI:10.1039/C7TA03070C
Co9S8 has received intensive attention as an electrode material for electrical energy storage (EES) systems due to its unique structural features and rich electrochemical properties. However, the instability and inferior rate capability of the Co9S8 electrode material during the charge/discharge process has restricted its applications in supercapacitors (SCs). Here, MOF-derived Co9S8 nanoparticles (NPs) embedded in carbon co-doped with N and S (Co9S8/NS–C) were synthesized as a high rate capability and super stable electrode material for SCs. The Co9S8/NS–C material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the Co9S8/NS–C material possessed a unique nanostructure in which Co9S8 NPs were encapsulated in porous graphitic carbon co-doped with N and S. The N/S co-doped porous graphitic carbon of composite led to improved rate performance by enhancing the stability of the electrode material and shortening the ion diffusion paths due to a synergistic effect. The as-prepared Co9S8/NS–C-1.5 h material exhibited a high specific capacitance of 734 F g−1 at a current density of 1 A g−1, excellent rate capability (653 F g−1 at 10 A g−1) and superior cycling stability, i.e., capacitance retention of about 99.8% after 140000 cycles at a current density of 10 A g−1. Thus, a new approach to fabricate promising electrode materials for high-performance SCs is presented here.
Co-reporter:Shuo Zhang, Daohao Li, Shuai Chen, Xianfeng Yang, Xiaoliang Zhao, Quansheng Zhao, Sridhar Komarneni and Dongjiang Yang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 24) pp:NaN12461-12461
Publication Date(Web):2017/05/12
DOI:10.1039/C7TA03070C
Co9S8 has received intensive attention as an electrode material for electrical energy storage (EES) systems due to its unique structural features and rich electrochemical properties. However, the instability and inferior rate capability of the Co9S8 electrode material during the charge/discharge process has restricted its applications in supercapacitors (SCs). Here, MOF-derived Co9S8 nanoparticles (NPs) embedded in carbon co-doped with N and S (Co9S8/NS–C) were synthesized as a high rate capability and super stable electrode material for SCs. The Co9S8/NS–C material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the Co9S8/NS–C material possessed a unique nanostructure in which Co9S8 NPs were encapsulated in porous graphitic carbon co-doped with N and S. The N/S co-doped porous graphitic carbon of composite led to improved rate performance by enhancing the stability of the electrode material and shortening the ion diffusion paths due to a synergistic effect. The as-prepared Co9S8/NS–C-1.5 h material exhibited a high specific capacitance of 734 F g−1 at a current density of 1 A g−1, excellent rate capability (653 F g−1 at 10 A g−1) and superior cycling stability, i.e., capacitance retention of about 99.8% after 140000 cycles at a current density of 10 A g−1. Thus, a new approach to fabricate promising electrode materials for high-performance SCs is presented here.
Co-reporter:Guichao Ye, Xiaoyi Zhu, Shuai Chen, Daohao Li, Yafang Yin, Yun Lu, Sridhar Komarneni and Dongjiang Yang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 18) pp:NaN8254-8254
Publication Date(Web):2017/04/12
DOI:10.1039/C7TA02334K
We developed a unique industrial-scale sustainable biomass conversion strategy for the synthesis of multifunctional, three-dimensional (3D) carbon nanofiber (CNF) aerogels with hierarchical porosity. The above aerogels were also highly nitrogen-doped through pyrolysis of bamboo cellulose. The important and critical part of our synthesis strategy was to assemble the nanofibers of cellulose (NFC) from bamboo to make aerogels of controlled porosity with a hierarchical porous structure. The as-prepared CNF aerogels with abundant chemical reaction sites and three-dimensional electron and ion transport pathways were found to be new high-performance anode materials for lithium-ion batteries (LIBs). In particular, the N-doped CNF aerogel prepared with 1 D fibers of 50 nm in diameter as building-blocks exhibited a high reversible capacity of 630.7 mA h g−1 at 1 A g−1, excellent rate capability (289 mA h g−1 at 20 A g−1) and excellent cycling performance (651 mA h g−1 at 1 A g−1 after 1000 cycles) in LIBs.
Co-reporter:Chunxiao Lv, Xianfeng Yang, Ahmad Umar, Yanzhi Xia, Yi(Alec) Jia, Lu Shang, Tierui Zhang and Dongjiang Yang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 45) pp:NaN22715-22715
Publication Date(Web):2015/09/21
DOI:10.1039/C5TA06393K
The increasing demand for high performance lithium ion batteries (LIBs) has aroused great interest in developing high specific capacity, cycle performance and rate capability anode materials. Transition metal oxides (TMOs) have attracted much attention as promising anode materials for rechargeable LIBs owing to their high theoretical capacity. Here, a general strategy has been developed to fabricate high-performance fibrous TMO anodes such as elemental Ni doped NiO fibre (NiO/Ni/C-F), yolk–shell structured carbon@Fe2O3 fibre (C@Fe2O3-F), and hollow CuO fibre (CuO-HF) with controllable nanostructures by using alginate microfibres as templates. The key to the formation of various TMO micro-/nano-structures is the templating ability of the natural structure of long alginate molecular chains, where the metal cations can be confined in an “egg-box” via coordination with negatively charged α-L-guluronate blocks. When tested as anode materials for LIB half cells, these fibrous electrodes deliver excellent cycling performance with no capacity decrease after 200 cycles (793 mA h g−1, NiO/Ni/C-F, 0.072 A g−1; 1035 mA h g−1, C@Fe2O3-F, 0.1 A g−1; 670 mA h g−1, CuO-HF, 0.067 A g−1), and demonstrate great rate performance at different current densities. This finding highlights a general, green and eco-friendly strategy for the scale-up production of potential high-performance TMO anodes for LIBs.
Co-reporter:Wei Zhao, Pei Yuan, Xilin She, Yanzhi Xia, Sridhar Komarneni, Kai Xi, Yanke Che, Xiangdong Yao and Dongjiang Yang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 27) pp:NaN14194-14194
Publication Date(Web):2015/06/19
DOI:10.1039/C5TA03199K
A high-performance one-dimensional (1D) nanofibrillar N–Co–C oxygen reduction reaction (ORR) catalyst was fabricated via electrospinning using renewable natural alginate and multiwalled carbon nanotubes (MWCNTs) as precursors, where Co nanoparticles (NPs) are encapsulated by nitrogen (N)-doped amorphous carbon and assembled on MWCNTs. The 1D morphology not only prevents the aggregation of the Co NPs, but also provides a typical multimodal mesoporous structure which is beneficial for the O2 diffusion and the migration of adsorbed superoxide. In combination with the high conductivity of CNTs, the N-doped amorphous carbon shell can exert electron release on the encapsulated Co NPs, and thus enhance the ORR activity. It is also a protective layer that stabilizes the Co NPs, which ensures a high ORR activity of the catalysts in both alkaline and acid media and long-term durability. So compared with a commercial Pt/C catalyst, as expected, the N–Co–C nanofiber reported herein exhibited a comparable current density and onset potential (−0.06 V), with better durability in alkaline and acid solutions and better resistance to crossover effects in the ORR.
Co-reporter:Na Ma, Yi (Alec) Jia, Xianfeng Yang, Xilin She, Longzhou Zhang, Zhi Peng, Xiangdong Yao and Dongjiang Yang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 17) pp:NaN6384-6384
Publication Date(Web):2016/03/21
DOI:10.1039/C6TA00591H
Developing earth-abundant, active and stable electrocatalysts which operate in two-electrode rechargeable metal–air batteries, including both oxygen evolution and reduction reactions (OER and ORR), is vital for renewable energy conversion in real application. Here, we demonstrate a three-dimensional (3D) bifunctional nanoaerogel electrocatalyst that exhibits good electrocatalytic properties for both OER and ORR. This material was fabricated using a scalable and facile method involving the pyrolysis of (Ni,Co)/CNT alginate hydrogels derived from sustainable seaweed biomass after an ion exchange process. The bifunctionality for oxygen electrocatalysis as shown by the OER–ORR potential difference (ΔE, the OER and ORR potentials are taken at the current densities of 10 mA cm−2 and −3 mA cm−2 in 0.1 M KOH, respectively) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts. The good performance was attributed to the ternary Ni/NiO/NiCo2O4 catalytic center for charge transfer and 3D hierarchical mesoporous hybrid framework for efficient mass transport. More importantly, the Zn–air battery fabricated with the hybrid nanoaerogel as a bifunctional electrocatalyst displays very high energy efficiency (58.5%) and long-term stability. Prospectively, our present work may pave a new way to develop earth-abundant and low cost high-performance bifunctional electrocatalysts for rechargeable metal–air batteries.
