Yimin Chao

Find an error

Name:

Organization: University of East Anglia , England

Department: School of Chemistry

Title: (PhD)

TOPICS

Material Chemistry

Chemicals
References

Significantly Enhanced Thermoelectric Performance of γ-In2Se3 through Lithiation via Chemical Diffusion

Co-reporter:Jiaolin Cui, Hua Peng, Zhiliang Song, Zhengliang Du, Yimin Chao, and Gang Chen

Chemistry of Materials September 12, 2017 Volume 29(Issue 17) pp:7467-7467

Publication Date(Web):August 9, 2017

DOI:10.1021/acs.chemmater.7b02467

γ-In2Se3 is selected as a thermoelectric candidate because it has a unique crystal structure and thermal stability at relatively high temperatures. In this work, we have prepared lithiated γ-In2Se3 through chemical diffusion and investigated its band structures and thermoelectric performance. After lithiation of γ-In2Se3 in a lithium acetate (CH3COOLi) solution at 50 °C for 30 h, we have observed a high Hall carrier concentration (nH) of ≤1.71 × 1018 cm–3 at room temperature, which is ∼4 orders of magnitude higher than that of pristine γ-In2Se3. The enhancement of nH is directly responsible for the remarkable improvement in electrical conductivity and can be elucidated as the Fermi level (Fr) unpinning and moving toward the conduction band through the dominant interstitial occupation of Li+ in the γ-In2Se3 lattice. Combined with the minimum lattice thermal conductivity (κL = 0.30–0.34 W K–1 m–1) at ∼923 K, the highest ZT value of 0.62–0.67 is attained, which is approximately 9–10 times that of pristine γ-In2Se3, proving that the lithiation in γ-In2Se3 is an effective approach to the improvement in thermoelectric performance.

The role of excess Sn in Cu4Sn7S16 for modification of the band structure and a reduction in lattice thermal conductivity

Co-reporter:Tongtong He;Naiming Lin;Zhengliang Du;Jiaolin Cui

Journal of Materials Chemistry C 2017 vol. 5(Issue 17) pp:4206-4213

Publication Date(Web):2017/05/04

DOI:10.1039/C7TC00420F

In this work, we have investigated the band structures of ternary Cu4Sn7+xS16 (x = 0–1.0) compounds with an excess of Sn, and examined their thermoelectric (TE) properties. First principles calculations reveal that the excess Sn, which exists as Sn2+ and is preferentially located at the intrinsic Cu vacancies, unpins the Fermi level (Fr) and allows Fr to enter the conduction band (CB) at x = 0.5. Accordingly, the Hall carrier concentration (nH) is enhanced by about two orders of magnitude when the x value increases from x = 0 to x = 0.5. Meanwhile, the lattice thermal conductivity (κL) is reduced significantly to 0.39 W K−1 m−1 at 893 K, which is in reasonably good agreement with the estimation using the Callaway model. As a consequence, the dimensionless TE figure of merit (ZT) of the compound Cu4Sn7+xS16 with x = 0.5 reaches 0.41 at 863 K. This value is double that of the stoichiometric Cu4Sn7S16, proving that excess Sn in Cu4Sn7S16 is beneficial for improving the TE performance.

Enhanced thermoelectric performance via the solid solution formation: The case of pseudobinary alloy (Cu2Te)(Ga2Te3)3 upon Sb substitution for Cu

Co-reporter:Jiaolin Cui, Xianglian Liu, Zhengliang Du, Yimin Chao

Materials & Design 2017 Volume 115(Volume 115) pp:

Publication Date(Web):5 February 2017

DOI:10.1016/j.matdes.2016.11.024

•The reduction of the lattice thermal conductivity (κL) has been quantified in Sb-incorporated (Cu2Te)(Ga2Te3)3 alloy.•A preference of Sb3 + at Cu+ site with x ≤ 0.05 and at Ga3 + sides with x ≥ 0.05 has been determined.•A remarkable improvement in TE performance has been achieved through solid solution formation.In this work we have observed the beneficial effect from the solid solution formation on the thermoelectric performance of (Cu2(1 − x)Sb2xTe)(Ga2Te3)3 upon Sb substitution for Cu. This substitution allows the different occupations of Sb in the crystal lattice, i.e. Sb at Cu sites with x ≤ 0.05 and at Ga sides with x ≥ 0.05, which has resulted in the Pisarenko relation does not exactly capture the measured Seebeck coefficient under assumed effective masses m*. The reduction of the lattice thermal conductivity (κL) has been quantified within the temperature range from room temperature to 723 K. Over the entire composition range, the κL value is reduced by 33% and 25% at temperature 723 K and 580 K, respectively. This observation is in a good agreement with the theoretical calculation based on the Callaway model used in the solid solutions. Along with the increasing of the mobility and electrical conductivity, the thermoelectric performance has been improved with the highest ZT value of 0.58 at 723 K, which is about double the value of intrinsic (Cu2Te)(Ga2Te3)3.Download high-res image (256KB)Download full-size image

Hybrid Silicon Nanostructures with Conductive Ligands and Their Microscopic Conductivity

Co-reporter:Tiezheng Bian;Jamie N. Peck;Stephen P. Cottrell

Journal of Electronic Materials 2017 Volume 46( Issue 5) pp:3221-3226

Publication Date(Web):23 September 2016

DOI:10.1007/s11664-016-4954-y

Silicon nanoparticles (SiNPs) functionalized with conjugated molecules are a promising potential pathway for generating an alternative category of thermoelectric materials. While the thermoelectric performance of materials based on phenylacetylene-capped SiNPs has been proven, their low conductivity is still a problem for their general application. A muon study of phenylacetylene-capped SiNPs was recently carried out using the HIFI spectrometer at the Rutherford Appleton Laboratory, measuring the avoided level-crossing spectra as a function of temperature. The results show a reduction in the measured line width of the resonance above room temperature, suggesting an activated behaviour for this system. This study shows that the muon study could be a powerful method for investigating microscopic conductivity of hybrid thermoelectric materials.

An active core-shell nanoscale design for high voltage cathode of lithium storage devices

Co-reporter:Zhongpei Lu, Yang Liu, Xiaojun Lu, Hao Wang, Gang Yang, Yimin Chao, Weili Li, Fan Yin

Journal of Power Sources 2017 Volume 360(Volume 360) pp:

Publication Date(Web):31 August 2017

DOI:10.1016/j.jpowsour.2017.06.036

•LiNi0.5Mn1.5O4@LiCoPO4 synthesized by co-precipitation and hydrothermal reaction.•LiCoPO4 induced Mn3+ to improve the conductivity of LiNi0.5Mn1.5O4.•LiCoPO4 shell decreases the decomposition of LiPF6 and preventing the loss of Mn3+.•LNM@5%LCP delivers 128 mAh g−1 at 0.5 C and remain 96% capacity after 100 cycles.•LNM@5%LCP delivers 115 mAh g−1 at 20 C higher than 57 mAh g−1 of pure LiNi0.5Mn1.5O4.Spinel LiNi0.5Mn1.5O4 (LNM) is a potential high-voltage cathode for commercial lithium-ion batteries (LIBs). Maintaining an appropriate amount of Mn3+ in LNM is necessary to improve the rate performance. However, Mn3+ dissolution in the interface of LNM and electrolyte leads to the fast capacity degradation. Therefore, designing a cathode to prevent Mn3+ loss during charge/discharge is important for high performance LIBs. Here we present an active core-shell design with coating another high-voltage cathode material LiCoPO4 (LCP) on the surface of LNM nanoparticles. The LCP layer can simultaneously induce Mn3+ ions at the interface between LCP and LNM, and act as a stable shell to prevent the loss of Mn3+. The optimized sample LNM@5%LCP possesses 128 mAh g−1 at 0.5 C and 115 mAh g−1 at 20 C rate, and maintains 96% of the initial capacity operated at 55 °C over 100 cycles.Download high-res image (355KB)Download full-size image

Enhancing the thermoelectric performance of Cu3SnS4-based solid solutions through coordination of the Seebeck coefficient and carrier concentration

Co-reporter:Yuanbo Yang;Pengzhan Ying;Jinzhi Wang;Xianglian Liu;Zhengliang Du;Jiaolin Cui

Journal of Materials Chemistry A 2017 vol. 5(Issue 35) pp:18808-18815

Publication Date(Web):2017/09/12

DOI:10.1039/C7TA05253G

Improving the thermoelectric (TE) performance of Cu3SnS4 is challenging because it exhibits a metallic behavior, therefore, a strategy should be envisaged to coordinate the carrier concentration (nH) and Seebeck coefficient (α). The coordination in this work has been realized through the Fermi level (Ef) unpinning and shifting towards the conduction band (CB) via addition of excess Sn in Cu3SnS4. As a result, the solid solution Cu3Sn1+xS4 (x = 0.2) has a moderate α (178.0 μV K−1) at 790 K and a high nH (1.54 × 1021 cm−3) value. Along with the lowest lattice thermal conductivity κL (0.39 W K−1 m−1) caused by the increased phonon scattering by carriers, the highest ZT value of 0.75 is attained at ∼790 K. This value is 2.8 times that of the stoichiometric Cu3SnS4, and stands among the highest for ternary Cu–Sn–S sulfide thermoelectrics at the corresponding temperatures. More importantly, this approach used in the case of ternary Cu3SnS4 provides a guidance or reference to improve the TE performance of other materials.

Synthesis of Diagnostic Silicon Nanoparticles for Targeted Delivery of Thiourea to Epidermal Growth Factor Receptor-Expressing Cancer Cells

Co-reporter:Mehrnaz Behray, Carl A. Webster, Sara Pereira, Paheli Ghosh, Satheesh Krishnamurthy, Wafa T. Al-Jamal, and Yimin Chao

ACS Applied Materials & Interfaces 2016 Volume 8(Issue 14) pp:8908

Publication Date(Web):March 23, 2016

DOI:10.1021/acsami.5b12283

The novel thiourea-functionalized silicon nanoparticles (SiNPs) have been successfully synthesized using allylamine and sulforaphane, an important anticancer drug, followed by a hydrosilylation reaction on the surface of hydrogen terminated SiNPs. Their physiochemical properties have been investigated by photoluminescence emission, Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay has been employed to evaluate in vitro toxicity in human colorectal adenocarcinoma (Caco-2) cells and human normal colon epithelial (CCD) cells. The results show significant toxicity of thiourea SiNPs after 72 h of incubation in the cancer cell line, and the toxicity is concentration dependent and saturated for concentrations above 100 μg/mL. Confocal microscopy images have demonstrated the internalization of thiourea-functionalized SiNPs inside the cells. Flow cytometry data has confirmed receptor-mediated targeting in cancer cells. This nanocomposite takes advantage of the epidermal growth factor receptor (EGFR) active targeting of the ligand in addition to the photoluminescence properties of SiNPs for bioimaging purposes. The results suggest that this novel nanosystem can be extrapolated for active targeting of the receptors that are overexpressed in cancer cells such as EGFR using the targeting characteristics of thiourea-functionalized SiNPs and therefore encourage further investigation and development of anticancer agents specifically exploiting the EGFR inhibitory activity of such nanoparticles.Keywords: colon cancer; epidermal growth factor; imaging; silicon nanoparticles; thiourea;

Engineering Band Structure via the Site Preference of Pb2+ in the In+ Site for Enhanced Thermoelectric Performance of In6Se7

Co-reporter:Jiaolin Cui, Min Cheng, Wenchang Wu, Zhengliang Du, and Yimin Chao

ACS Applied Materials & Interfaces 2016 Volume 8(Issue 35) pp:23175

Publication Date(Web):August 19, 2016

DOI:10.1021/acsami.6b07238

Although binary In–Se based alloys have in recent years gained interest as thermoelectric (TE) candidates, little attention has been paid to In6Se7-based compounds. Substituting Pb in In6Se7, preference for Pb2+ in the In+ site has been observed, allowing Fermi level (Fr) shift toward the conduction band, where the localized state conduction becomes dominant. Consequently, the Hall carrier concentration (nH) has been significantly enhanced with the highest nH value being about 2–3 orders of magnitude higher than that of the Pb-free sample. Meanwhile, the lattice thermal conductivity (κL) tends to be reduced as the nH value increases, owing to an increased phonon scattering on carriers. As a result, a significantly enhanced TE performance has been achieved with the highest TE figure of merit (ZT) of 0.4 at ∼850 K. This ZT value is 27 times that of intrinsic In6Se7 (ZT = 0.015 at 640 K), which proves a successful band structure engineering through site preference of Pb in In6Se7.Keywords: band structure engineering; carrier concentration; fermi level; In6Se7; site preference; thermoelectric performance

Hydrogen-terminated mesoporous silicon monoliths with huge surface area as alternative Si-based visible light-active photocatalysts

Co-reporter:Ting Li, Jun Li, Qiang Zhang, Emma Blazeby, Congxiao Shang, Hualong Xu, Xixiang Zhang and Yimin Chao

RSC Advances 2016 vol. 6(Issue 75) pp:71092-71099

Publication Date(Web):21 Jul 2016

DOI:10.1039/C6RA09474K

Silicon-based nanostructures and their related composites have drawn tremendous research interest in solar energy storage and conversion. Mesoporous silicon with a huge surface area of 400–900 m2 g−1 developed by electrochemical etching exhibits excellent photocatalytic ability and stability after 10 cycles in degrading methyl orange under visible light irradiation, owing to its unique mesoporous network, abundant surface hydrides and efficient light harvesting. This work showcases the profound effects of surface area, crystallinity, pore topology on charge migration/recombination and mass transportation. Therein the ordered 1D channel array has outperformed the interconnected 3D porous network by greatly accelerating the mass diffusion and enhancing the accessibility of the active sites on the extensive surfaces.

Ligand Doping on the Hybrid Thermoelectric Materials Based on Terthiophene-Capped Silicon Nanoparticles

Co-reporter:Shane P. Ashby;Tiezheng Bian;Gabin Guélou

Journal of Electronic Materials 2016 Volume 45( Issue 3) pp:1260-1265

Publication Date(Web):2016 March

DOI:10.1007/s11664-015-3988-x

Over the past 2 years, silicon nanoparticles (SiNPs) functionalised with conjugated molecules have been shown to have potential as low-temperature thermoelectric materials. One key challenge with such materials relates to the introduction of charge carriers. There are two components of organic/silicon nanocomposite materials in which charge carriers can be introduced: the silicon nanoparticle or the organic ligand. Investigation into the effect of introducing charge carriers on the ligands via oxidation is another step towards understanding and optimising this kind of system. Terthiophene-capped SiNPs have been synthesised and characterised before and after doping. Using different ratios and the oxidant NOBF4 to dope the surface ligands, the electrical conductivity has been measured at ambient temperature. The ratio of oxidant to nanoparticles shows similar trends in electrical resistivity to that of conventional conductive polymers and shows significant improvements over the undoped material.

Synthesis of Carbohydrate Capped Silicon Nanoparticles and their Reduced Cytotoxicity, In Vivo Toxicity, and Cellular Uptake

Co-reporter:Jayshree H. Ahire;Mehrnaz Behray;Carl A. Webster;Qi Wang;Victoria Sherwood;Nattika Saengkrit;Uracha Ruktanonchai;Noppawan Woramongkolchai

Advanced Healthcare Materials 2015 Volume 4( Issue 12) pp:1877-1886

Publication Date(Web):

DOI:10.1002/adhm.201500298

The development of smart targeted nanoparticles (NPs) that can identify and deliver drugs at a sustained rate directly to cancer cells may provide better efficacy and lower toxicity for treating primary and advanced metastatic tumors. Obtaining knowledge of the diseases at the molecular level can facilitate the identification of biological targets. In particular, carbohydrate-mediated molecular recognitions using nano-vehicles are likely to increasingly affect cancer treatment methods, opening a new area in biomedical applications. Here, silicon NPs (SiNPs) capped with carbohydrates including galactose, glucose, mannose, and lactose are successfully synthesized from amine terminated SiNPs. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] analysis shows an extensive reduction in toxicity of SiNPs by functionalizing with carbohydrate moiety both in vitro and in vivo. Cellular uptake is investigated with flow cytometry and confocal fluorescence microscope. The results show the carbohydrate capped SiNPs can be internalized in the cells within 24 h of incubation, and can be taken up more readily by cancer cells than noncancerous cells. Moreover, these results reinforce the use of carbohydrates for the internalization of a variety of similar compounds into cancer cells.

Synthesis of low-oxide blue luminescent alkyl-functionalized silicon nanoparticles with no nitrogen containing surfactant

Co-reporter:Jason A. Thomas;Shane P. Ashby;Frederik Huld

Journal of Nanoparticle Research 2015 Volume 17( Issue 5) pp:

Publication Date(Web):2015 May

DOI:10.1007/s11051-015-3039-9

Of ever growing interest in the fields of physical chemistry and materials science, silicon nanoparticles show a great deal of potential. Methods for their synthesis are, however, often hazardous, expensive or otherwise impractical. In the literature, there is a safe, fast and cheap inverse micelle-based method for the production of alkyl-functionalized blue luminescent silicon nanoparticles, which nonetheless found limitations, due to undesirable Si-alkoxy and remaining Si–H functionalization. In the following work, these problems are addressed, whereby an optimisation of the reaction mechanism encourages more desirable capping, and the introduction of alcohol is replaced by the use of anhydrous copper (II) chloride. The resulting particles, when compared with their predecessors through a myriad of spectroscopic techniques, are shown to have greatly reduced levels of ‘undesirable’ capping, with a much lower surface oxide level; whilst also maintaining long-term air stability, strong photoluminescence and high yields.

Novel Approach to the Preparation of Organic Energetic Film for Microelectromechanical Systems and Microactuator Applications

Co-reporter:Jun Wang, Wenchao Zhang, Lianwei Wang, Ruiqi Shen, Xing Xu, Jiahai Ye, and Yimin Chao

ACS Applied Materials & Interfaces 2014 Volume 6(Issue 14) pp:10992

Publication Date(Web):July 6, 2014

DOI:10.1021/am5028617

An activated RDX–Fe2O3 xerogel in a Si-microchannel plate (MCP) has been successfully prepared by a novel propylene epoxide-mediated sol–gel method. A decrease of nearly 40 °C in decomposition temperature has been observed compared with the original cyclotrimethylene trinitramine (RDX). The RDX–Fe2O3 xerogel can release gas and solid matter simultaneously, and the ratio of gas to solid can be tailored easily by changing the initial proportions of RDX and FeCl3·6H2O, which significantly enhances the explosive and propulsion effects and is of great benefit to the applications. The approach, which is simple, safe, and fully compatible with MEMS technology, opens a new route to the introduction of organic energetic materials to a silicon substrate.Keywords: energetic materials; MEMS; microactuator; nanoscale RDX; silicon microchannel plate

Amine-terminated nanoparticle films: pattern deposition by a simple nanostencilling technique and stability studies under X-ray irradiation

Co-reporter:P. R. Coxon, J. H. Ahire, S. P. Ashby, M. D. Frogley and Y. Chao

Physical Chemistry Chemical Physics 2014 vol. 16(Issue 12) pp:5817-5823

Publication Date(Web):18 Feb 2014

DOI:10.1039/C3CP55344B

Thin films made up of arrays of amine-terminated silicon nanoparticles (NH2-SiNPs) synthesized by a new evaporation technique have been formed by employing TEM grids as nanostencils. FTIR imaging illustrates the feasibility of the method in nanoscale device fabrication applications. Micro-mapping over areas of the nanoparticle material allows the surface chemistry to be examined. FTIR imaging shows trace amounts of oxide confined to the NP surfaces. Thicker films formed by dropcasting allowed the nanoparticle behaviour to be studied under conditions of extended exposure to 150 eV photons radiation by X-ray photoelectron spectroscopy (XPS). The XPS spectrum was monitored over the Si2p region and the initial peak at 100.53 eV was observed to shift to higher binding energies as irradiation progressed which is indicative of charge trapping within the film. This result has potential consequences for applications where NH2-SiNPs are used in X-ray environments such as in bioimaging where the increasing charge buildup is related to enhanced cytotoxicity.

Significantly Enhanced Energy Output from 3D Ordered Macroporous Structured Fe2O3/Al Nanothermite Film

Co-reporter:Wenchao Zhang, Baoqing Yin, Ruiqi Shen, Jiahai Ye, Jason A. Thomas, and Yimin Chao

ACS Applied Materials & Interfaces 2013 Volume 5(Issue 2) pp:239

Publication Date(Web):December 31, 2012

DOI:10.1021/am302815y

A three-dimensionally ordered macroporous Fe2O3/Al nanothermite membrane has been prepared with a polystyrene spheres template. The nanothermite, with an enhanced interfacial contact between fuel and oxidizer, outputs 2.83 kJ g–1 of energy. This is significantly more than has been reported before. This approach, fully compatible with MEMS technology, provides an efficient way to produce micrometer thick three-dimensionally ordered nanostructured thermite films with overall spatial uniformity. These exciting achievements will greatly facilitate potential for the future development of applications of nanothermites.Keywords: metastable intermolecular composites; microelectro-mechanical system; nanoenergetic materials; nanothemite; polystyrene spheres template;

Synthesis of d-Mannose Capped Silicon Nanoparticles and Their Interactions with MCF-7 Human Breast Cancerous Cells

Co-reporter:Jayshree H. Ahire, Isabelle Chambrier, Anja Mueller, Yongping Bao, and Yimin Chao

ACS Applied Materials & Interfaces 2013 Volume 5(Issue 15) pp:7384

Publication Date(Web):July 2, 2013

DOI:10.1021/am4017126

Silicon nanoparticles (SiNPs) hold prominent interest in various aspects of biomedical applications. For this purpose, surface functionalization of the NPs is essential to stabilize them, target them to specific disease area, and allow them to selectively bind to the cells or the bio-molecules present on the surface of the cells. However, no such functionalization has been explored with Si nanoparticles. Carbohydrates play a critical role in cell recognition. Here, we report the first synthesis of silicon nanoparticles functionalized with carbohydrates. In this study, stable and brightly luminescent d-Mannose (Man) capped SiNPs have been synthesized from amine terminated SiNPs and d-mannopyranoside acid. The surface functionalization is confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and energy dispersive X-ray spectroscopy (EDX) studies. The mean diameter of the crystal core is 5.5 nm, as measured by transmission electron microscopy (TEM), while the hydrodynamic diameter obtained by dynamic light scattering (DLS) is 16 nm. The quantum yield (QY) of photoluminescence emission is found to be 11.5%, and the nanoparticles exhibit an exceptional stability over two weeks. The Man-capped SiNPs may prove to be valuable tools for further investigating glycobiological, biomedical, and material science fields. Experiments are carried out using Concanavalin A (ConA) as a target protein in order to prove the hypothesis. When Man functionalized SiNPs are treated with ConA, cross-linked aggregates are formed, as shown in TEM images as well as monitored by photoluminescence spectroscopy (PL). Man functionalized SiNPs can target cancerous cells. Visualization imaging of SiNPs in MCF-7 human breast cancer cells shows the fluorescence is distributed throughout the cytoplasm of these cells.Keywords: cancerous cells; d-mannose; fluorescence imaging; nanoparticles; protein; silicon;

Co-encapsulation of Biodegradable Nanoparticles with Silicon Quantum Dots and Quercetin for Monitored Delivery

Co-reporter:Qi Wang;Yongping Bao;Jayshree Ahire

Advanced Healthcare Materials 2013 Volume 2( Issue 3) pp:459-466

Publication Date(Web):

DOI:10.1002/adhm.201200178

Abstract

Polymer nanoparticles have emerged as a promising new strategy for the efficient delivery of drugs. They have several advantages when used as drug carriers, such as high stability, high capacity, improvement of drug bioavailability, as well as allowing for sustained drug release. Quercetin has therapeutic potential as an anticancer drug, but has poor solubility and low bioavailability. In this study it is shown that co-encapsulation of quercetin and fluorescent Silicon quantum dots (SiQDs) in poly (ethylene glycol)-block-polylactide (PEG–PLA) nanoparticles can be used for simultaneous in vitro imaging and to improve the biocompatibility of quercetin. Fluorescent imaging with SiQDs can provide a new concept to monitor the delivery of anti-cancer drugs. The nanoparticles are synthesized based on the double emulsion method and are extensively characterized and assayed for cytotoxicity in vitro. HepG2 cells are incubated with quercetin and SiQDs dual-loaded PEG–PLA nanoparticles, resulting in a red fluorescent staining which can be detected with a confocal microscope. PEG–PLA nanoparticle encapsulated quercetin suppresses human hepatoma HepG2 cell proliferation more effectively than the free-standing form. In addition, nanoparticle-encapsulated quercetin significantly inhibits hydrogen peroxide-induced DNA damage in HepG2 cells. These data show that nanocapsulated quercetin possesses the potential bioactivity to reduce the drug dosage frequency, as well as increase patient compliance. The combination of polymeric nanoparticles and semiconductor quantum dots can allow monitoring of delivery, improve aqueous solubility, and enhance biocompatibility. Such nanoparticulated systems could shape the future of drug delivery.

Highly Luminescent and Nontoxic Amine-Capped Nanoparticles from Porous Silicon: Synthesis and Their Use in Biomedical Imaging

Co-reporter:Jayshree H. Ahire, Qi Wang, Paul R. Coxon, Girish Malhotra, Rik Brydson, Rongjun Chen, and Yimin Chao

ACS Applied Materials & Interfaces 2012 Volume 4(Issue 6) pp:3285

Publication Date(Web):May 24, 2012

DOI:10.1021/am300642m

Stable and brightly luminescent amine-terminated Si nanoparticles (SiNPs) have been synthesized from electrochemically etched porous silicon (PSi). The surface amine termination was confirmed by FTIR, NMR, and XPS studies. The mean diameter of the crystal core of 4.6 nm was measured by transmission electron microscopy (TEM), which is in a good agreement with the size obtained by dynamic light scattering (DLS). The dry, amine-terminated product can be obtained from bulk silicon wafers in less than 4 h. This represents a significant improvement over similar routines using PSi where times of >10 h are common. The emission quantum yield was found to be about 22% and the nanoparticles exhibited an exceptional stability over a wide pH range (4–14). They are resistant to aging over several weeks. The amine-terminated SiNPs showed no significant cytotoxic effects toward HepG2 cells, as assessed with MTT assays.Keywords: cellular imaging; FTIR; NMR; photoelectron spectroscopy; semiconductor nanoparticles; surface capping;

Uptake and Toxicity Studies of Poly-Acrylic Acid Functionalized Silicon Nanoparticles in Cultured Mammalian Cells

Co-reporter:Qi Wang;Yongping Bao;Xiaohong Zhang;Paul R. Coxon;Upali A. Jayasooriya

Advanced Healthcare Materials 2012 Volume 1( Issue 2) pp:189-198

Publication Date(Web):

DOI:10.1002/adhm.201100010

Abstract

Poly-acrylic acid (PAAc) terminated silicon nanoparticles (SiNPs) have been synthesized and employed as a synchronous fluorescent signal indicator in a series of cultured mammalian cells: HHL5, HepG2 and 3T3-L1. Their biological effects on cell growth and proliferation in both human and mouse cell lines have been studied. There was no evidence of in vitro cytotoxity in the cells exposed to PAAc terminated SiNPS when assessed by cell morphology, cell proliferation and viability, and DNA damage assays. The uptake of the nanocrystals by both HepG2 and 3T3-L1 cells was investigated by confocal microscopy and flow cytometry, which showed a clear time-dependence at higher concentrations. Reconstructed 3-D confocal microscope images exhibited that the PAAc-SiNPs were evenly distributed throughout the cytosol rather than attached to outer membrane. This study provides fundamental evidence for the safe application and further modification of silicon nanoparticles, which could broaden their application as cell markers in living systems and in micelle encapsulated drug delivery systems.

A hierarchical porous microstructure for improving long-term stability of Ni1-xCux/SDC anode-supported IT-SOFCs fueled with dry methane

Co-reporter:Zhicheng Wang, Siqi Wang, Shiyan Jiao, Wenjian Weng, Kui Cheng, Bin Qian, Hailin Yu, Yimin Chao

Journal of Alloys and Compounds (25 April 2017) Volume 702() pp:

Publication Date(Web):25 April 2017

DOI:10.1016/j.jallcom.2017.01.212

•A Ni1-xCux alloy-based anode possessing a hierarchical porous structure was prepared.•Such a novel anode was fabricated by co-pressing and co-sintering process.•The smaller pores were homogeneously distributed in the anode matrix.•The performance of the cell was improved with dry CH4 fuel.•Durability test showed only 2.4% power density drop after 72 h operation.A series of Ni1-xCux/Sm-doped ceria (Ni1-xCux/SDC) anodes have been prepared through introducing a soluble pore former with the co-pressing and co-sintering process. Uniform hierarchical porous microstructures are formed in Ni0.9Cu0.1/SDC anode with interconnected large pores of 2–5 μm and 100–300 nm small pores on the wall. The solid oxide fuel cell (SOFC) based on such anode exhibits exceptional electrochemical catalytic activity for dry CH4 oxidation and a maximum power density of 379 mW cm−2 is acquired at 600 °C. Durability test results show only 2.4% power density drop is observed after 72 h operation under a constant cell voltage of 0.5 V. The results have demonstrated that the optimization of anode microstructures is an effective way to improve the performance and long-term stability of Ni1-xCux alloy-based anode-supported SOFC.

Amine-terminated nanoparticle films: pattern deposition by a simple nanostencilling technique and stability studies under X-ray irradiation

Co-reporter:P. R. Coxon;J. H. Ahire;S. P. Ashby;M. D. Frogley;Y. Chao

Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 12) pp:

Publication Date(Web):2014/02/25

DOI:10.1039/C3CP55344B

The role of excess Sn in Cu4Sn7S16 for modification of the band structure and a reduction in lattice thermal conductivity

Co-reporter:Tongtong He, Naiming Lin, Zhengliang Du, Yimin Chao and Jiaolin Cui

Journal of Materials Chemistry A 2017 - vol. 5(Issue 17) pp:NaN4213-4213

Publication Date(Web):2017/03/31

DOI:10.1039/C7TC00420F

Engineering the energy gap near the valence band edge in Mn-incorporated Cu3Ga5Te9 for an enhanced thermoelectric performance

Co-reporter:Jiaolin Cui, Zheng Sun, Zhengliang Du and Yimin Chao

Journal of Materials Chemistry A 2016 - vol. 4(Issue 34) pp:NaN8019-8019

Publication Date(Web):2016/08/04

DOI:10.1039/C6TC02745H

Cu3Ga5Te9-based compounds Cu3−xGa5MnxTe9 (x = 0–0.2) with Mn substitution for Cu have been synthesized. The engineered energy gap (ΔEA) between impurity and valence bands is reduced from 44.4 meV at x = 0 to 25.7 meV at x = 0.1, which is directly responsible for the reduction of the potential barrier for thermal excitation of carriers and the increase in carrier concentration. However, the Seebeck coefficient shows an increasing tendency with the increase of determined Hall carrier concentration (n). This anomalous behavior suggests that the Pisarenko plots under assumed effective masses do not fit the current relationship between the Seebeck coefficient and the carrier density. With the combination of enhanced electrical conductivities and reduced thermal conductivities at high temperatures, the maximum thermoelectric (TE) figure of merit (ZT) of 0.81 has been achieved at 804 K with x = 0.1, which is about 1.65 and 2.9 times the value of current and reported intrinsic Cu3Ga5Te9. The remarkable improvement in TE performance proves that we have succeeded in engineering the energy gap near the valence band edge upon Mn incorporation into Cu3Ga5Te9.