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Prof. Kwang Leong Choy
UCL Institute for Materials Discovery, University College London, London, WC1E 7JE, United Kingdom

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Chemical vapour deposition
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Review article
Published: 24 June 2021 in Progress in Materials Science
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Electric field-induced transformations occur in a myriad of systems with a variegated phenomenology and have attracted widespread scientific interest due to their importance in many applications. The present review focuses on the electric field-induced transformations occurring in bismuth sodium titanate (BNT)-based materials, which are considered as an important family of lead-free perovskites and represent possible alternatives to lead-based compounds for several applications. BNT-based systems are generally classified as relaxor-ferroelectrics and are characterized by complex structures undergoing various electric field-driven phenomena. In this review, changes of crystal structure symmetry, domain configuration and macroscopic properties are discussed in relation to composition, temperature and electrical loading characteristics, including amplitude, frequency and DC biases. The coupling mechanisms between octahedral tilting with polarization and strain, and other microstructural features are identified as important factors mediating the local and overall electric field-induced response. The role of field-induced transformations on electrical fatigue is discussed by highlighting the effects of ergodicity on domain evolution and fatigue resistance in bipolar and unipolar cycles. The relevance of field-induced transformations in key applications, including energy storage capacitors, actuators, electrocaloric systems and photoluminescent devices is comprehensively discussed to identify materials design criteria. The review is concluded with an outlook for future research.

ACS Style

Giuseppe Viola; Ye Tian; Chuying Yu; Yongqiang Tan; Vladimir Koval; Xiaoyong Wei; Kwang-Leong Choy; Haixue Yan. Electric field-induced transformations in bismuth sodium titanate-based materials. Progress in Materials Science 2021, 122, 100837 .

AMA Style

Giuseppe Viola, Ye Tian, Chuying Yu, Yongqiang Tan, Vladimir Koval, Xiaoyong Wei, Kwang-Leong Choy, Haixue Yan. Electric field-induced transformations in bismuth sodium titanate-based materials. Progress in Materials Science. 2021; 122 ():100837.

Chicago/Turabian Style

Giuseppe Viola; Ye Tian; Chuying Yu; Yongqiang Tan; Vladimir Koval; Xiaoyong Wei; Kwang-Leong Choy; Haixue Yan. 2021. "Electric field-induced transformations in bismuth sodium titanate-based materials." Progress in Materials Science 122, no. : 100837.

Journal article
Published: 23 June 2021 in ACS Applied Materials & Interfaces
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Narrow-band-gap III–V semiconductor nanowires (NWs) with a suitable band structure and strong light-trapping ability are ideal for high-efficiency low-cost solar water-splitting systems. However, due to their nanoscale dimension, they suffer more severe corrosion by the electrolyte solution than the thin-film counterparts. Thus, short-term durability is the major obstacle for using these NWs for practical water-splitting applications. Here, we demonstrated for the first time that a thin layer (∼7 nm thick) of compact TiO2 deposited by atomic layer deposition can provide robust protection to III–V NWs. The protected GaAs NWs maintain 91.4% of its photoluminescence intensity after 14 months of storage in ambient atmosphere, which suggests the TiO2 layer is pinhole-free. Working as a photocathode for water splitting, they exhibited a 45% larger photocurrent density compared with unprotected counterparts and a high Faraday efficiency of 91% and can also maintain a record-long highly stable performance among narrow-band-gap III–V NW photoelectrodes; after 67 h photoelectrochemical stability test reaction in a strong acid electrolyte solution (pH = 1), they show no apparent indication of corrosion, which is in stark contrast to the unprotected NWs that fully failed after 35 h. These findings provide an effective way to enhance both stability and performance of III–V NW-based photoelectrodes, which are highly important for practical applications in solar-energy-based water-splitting systems.

ACS Style

Fan Cui; Yunyan Zhang; H. Aruni Fonseka; Premrudee Promdet; Ali Imran Channa; Mingqing Wang; Xueming Xia; Sanjayan Sathasivam; Hezhuang Liu; Ivan P. Parkin; Hui Yang; Ting Li; Kwang-Leong Choy; Jiang Wu; Christopher Blackman; Ana M. Sanchez; Huiyun Liu. Robust Protection of III–V Nanowires in Water Splitting by a Thin Compact TiO2 Layer. ACS Applied Materials & Interfaces 2021, 13, 30950 -30958.

AMA Style

Fan Cui, Yunyan Zhang, H. Aruni Fonseka, Premrudee Promdet, Ali Imran Channa, Mingqing Wang, Xueming Xia, Sanjayan Sathasivam, Hezhuang Liu, Ivan P. Parkin, Hui Yang, Ting Li, Kwang-Leong Choy, Jiang Wu, Christopher Blackman, Ana M. Sanchez, Huiyun Liu. Robust Protection of III–V Nanowires in Water Splitting by a Thin Compact TiO2 Layer. ACS Applied Materials & Interfaces. 2021; 13 (26):30950-30958.

Chicago/Turabian Style

Fan Cui; Yunyan Zhang; H. Aruni Fonseka; Premrudee Promdet; Ali Imran Channa; Mingqing Wang; Xueming Xia; Sanjayan Sathasivam; Hezhuang Liu; Ivan P. Parkin; Hui Yang; Ting Li; Kwang-Leong Choy; Jiang Wu; Christopher Blackman; Ana M. Sanchez; Huiyun Liu. 2021. "Robust Protection of III–V Nanowires in Water Splitting by a Thin Compact TiO2 Layer." ACS Applied Materials & Interfaces 13, no. 26: 30950-30958.

Journal article
Published: 11 April 2021 in Applied Materials Today
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Ion-selective electrodes are employed in technological important fields, such as medical diagnosis, or water quality evaluation. Plasticized polymeric membranes containing ionophores are typically used in these devices. However, the low mechanical hardness and limited robustness of these electrodes combined with their low selectivity limit their use in high precision applications. In the present work, PVC-functionalised silica nanoparticles incorporated in a plasticized PVC film have been integrated into ion sensors for the first time applied to the detection of K+ in solution. This approach was used for the design of highly specific and mechanically robust systems using a fluidic chamber. The device presented a hardness in the range of 5.2 GPa, being 2 orders of magnitude higher than the one reported for plasticized PVC (0.059 GPa), and could measure the concentration of K+ with high specificity when compared to Ca2+ and Na+ ions compared to the conventional approach. The interactions of the sensing films with the ions in solution were systematically studied for different degrees of PVC functionalisation to allow the rational design of a robust and selective sensor. The final device exhibited one of the lowest signal drift ever reported, with 1.3 µV h−1. The system operated under fluid pressure and shear stress conditions of 45 mbar for at least 8 h while the control experiment, fabricated using the conventional composition without nanoparticles showed a significantly higher noise (circa 115.6 µV h−1) and degraded after 4 h of continuous measurements. The sensors here reported could also be used for the accurate determination of the concentration of K+ inside complex mixtures of ions such as simulated body fluids and human serum, leading to a plethora of applications in healthcare for the diagnosis and monitoring of diseases.

ACS Style

Antonio Ruiz-Gonzalez; Kwang Leong Choy. Highly selective and robust nanocomposite-based sensors for potassium ions detection. Applied Materials Today 2021, 23, 101008 .

AMA Style

Antonio Ruiz-Gonzalez, Kwang Leong Choy. Highly selective and robust nanocomposite-based sensors for potassium ions detection. Applied Materials Today. 2021; 23 ():101008.

Chicago/Turabian Style

Antonio Ruiz-Gonzalez; Kwang Leong Choy. 2021. "Highly selective and robust nanocomposite-based sensors for potassium ions detection." Applied Materials Today 23, no. : 101008.

Journal article
Published: 07 April 2021 in Nanomaterials
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Ion-selective electrodes are at the forefront of research nowadays, with applications in healthcare, agriculture and water quality analysis among others. Despite multiple attempts of miniaturization of these polyvinyl chloride (PVC) gel-based ion sensors, no ion-sensing devices with a thickness below the micrometer range, and operating using open circuit potential, have been developed so far. This work reports the causes of this thickness limitation in potassium-selective sensors. Highly homogeneous ion-sensing films were fabricated by a method based on aerosol assisted chemical vapour deposition, leading to smooth surfaces with 27 ± 11 nm of roughness. Such homogeneity allowed the systematic study of the performance and ionic diffusion properties of the sensing films at sub-micrometer scales. Sensitivities below the Nernst response were found at low thicknesses. The nature of this reduction in sensitivity was studied, and a difference in the superficial and bulk compositions of the films was measured. An optimal configuration was found at 15 µm, with a good selectivity against Na+ (KK + , Na + = −1.8) a limit of detection in the range of 10−4 M and esponse time below 40 s. The stability of sensors was improved by the deposition of protective layers, which expanded the lifespan of the ion sensors up to 5 weeks while preserving the Nernst sensitivity.

ACS Style

Antonio Ruiz-Gonzalez; Kwang-Leong Choy. Integration of an Aerosol-Assisted Deposition Technique for the Deposition of Functional Biomaterials Applied to the Fabrication of Miniaturised Ion Sensors. Nanomaterials 2021, 11, 938 .

AMA Style

Antonio Ruiz-Gonzalez, Kwang-Leong Choy. Integration of an Aerosol-Assisted Deposition Technique for the Deposition of Functional Biomaterials Applied to the Fabrication of Miniaturised Ion Sensors. Nanomaterials. 2021; 11 (4):938.

Chicago/Turabian Style

Antonio Ruiz-Gonzalez; Kwang-Leong Choy. 2021. "Integration of an Aerosol-Assisted Deposition Technique for the Deposition of Functional Biomaterials Applied to the Fabrication of Miniaturised Ion Sensors." Nanomaterials 11, no. 4: 938.

Short communication
Published: 23 March 2021 in Materials Letters
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Standard dialyzer membranes, designed for diffusive clearance, do not effectively clear protein-bound uremic toxins, such as indoxyl sulfate (IS). To increase protein-bound toxins removal, absorbents require a high specific surface area to achieve effective size-coupling removal of target toxins. However, the toxicity of a molecule is not necessarily determined by size alone. As proof of concept, we report on an electrospun polycaprolactone/chitosan (PCL/CS) fibrous absorbent for IS removal based on chemical structural interaction. A single unit (20 mm in length) of our PCL/CS absorbent achieved a 28% clearance of IS within an hour at both 40 mg/L and 5 mg/L concentrations in a single pass model. This fibrous absorbent structure offers new thoughts on absorbent design.

ACS Style

Siyu Xiong; Yaxuan Lyu; Andrew Davenport; Kwang Leong Choy. Chitosan based fibrous absorbents for indoxyl sulfate sorption. Materials Letters 2021, 293, 129744 .

AMA Style

Siyu Xiong, Yaxuan Lyu, Andrew Davenport, Kwang Leong Choy. Chitosan based fibrous absorbents for indoxyl sulfate sorption. Materials Letters. 2021; 293 ():129744.

Chicago/Turabian Style

Siyu Xiong; Yaxuan Lyu; Andrew Davenport; Kwang Leong Choy. 2021. "Chitosan based fibrous absorbents for indoxyl sulfate sorption." Materials Letters 293, no. : 129744.

Articles
Published: 09 March 2021 in Science China Materials
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Multifunctional devices are of great interest for integration and miniaturization on the same platform, but simple addition of functionalities would lead to excessively large devices. Here, the photodetection and chemical sensing device is developed based on two-dimensional (2D) glassy-graphene that meets similar property requirements for the two functionalities. An appropriate bandgap arising from the distorted lattice structure enables glassy graphene to exhibit comparable or even improved photodetection and chemical sensing capability, compared with pristine graphene. Due to strong interactions between glassy graphene and the ambient atmosphere, the devices are less sensitive to photoinduced desorption than the ones based on graphene. Consequently, the few-layer glassy graphene device delivers positive photoresponse, with a responsivity of 0.22 A W−1 and specific detectivity reaching ∼1010 Jones under 405 nm illumination. Moreover, the intrinsic defects and strain in glassy graphene can enhance the adsorption of analytes, leading to high chemical sensing performance. Specifically, the extracted signal-to-noise-ratio of the glassy graphene device for detecting acetone is 48, representing more than 50% improvement over the device based on graphene. Additionally, bias-voltage- and thickness-dependent volatile organic compound (VOC) sensing features are identified, indicating the few-layer glassy graphene is more sensitive. This study successfully demonstrates the potential of glassy graphene for integrated photodetection and chemical sensing, providing a promising solution for multifunctional applications further beyond.

ACS Style

Xiao Li; Xiao Dai; Hao Xu; Kai Shen; Jian Guo; Caihong Li; Guifu Zou; Kwang-Leong Choy; Ivan P. Parkin; Zhengxiao Guo; Huiyun Liu; Jiang Wu. Multifunctional two-dimensional glassy graphene devices for vis-NIR photodetection and volatile organic compound sensing. Science China Materials 2021, 64, 1964 -1976.

AMA Style

Xiao Li, Xiao Dai, Hao Xu, Kai Shen, Jian Guo, Caihong Li, Guifu Zou, Kwang-Leong Choy, Ivan P. Parkin, Zhengxiao Guo, Huiyun Liu, Jiang Wu. Multifunctional two-dimensional glassy graphene devices for vis-NIR photodetection and volatile organic compound sensing. Science China Materials. 2021; 64 (8):1964-1976.

Chicago/Turabian Style

Xiao Li; Xiao Dai; Hao Xu; Kai Shen; Jian Guo; Caihong Li; Guifu Zou; Kwang-Leong Choy; Ivan P. Parkin; Zhengxiao Guo; Huiyun Liu; Jiang Wu. 2021. "Multifunctional two-dimensional glassy graphene devices for vis-NIR photodetection and volatile organic compound sensing." Science China Materials 64, no. 8: 1964-1976.

Research article
Published: 06 March 2021 in Energy Technology
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The electrochemical potentials of spinel lithium manganese oxide (LMO) have long been plagued by the significant Mn3+ dissolution during long cycle discharging, resulting in rapid capacity fading and short cycle life. Although the doping mechanisms are effective in suppressing these reactions, the correlations of their effects on the material properties and the improved discharging performance still remain uncovered. In this study, seven machine learning (ML) methods are applied to a manually curated dataset of 102 doped LMO spinel systems to predict the initial discharge capacities (IC) and 20th cycle end discharge capacities (EC) from fundamental system properties like material molar mass and crystal structure dimension. Gradient boosting models achieved the best prediction powers for IC and EC with their errors estimated to be 11.90 and 11.77 mAhg−1, respectively. Besides, a higher formula molar mass of doped LMO can improve both capacities and additionally, a shorter crystal lattice dimension with a dopant with smaller electronegativity can slightly improve the value of the IC and EC, respectively. This study demonstrates the great potential of using ML models to both predict the discharging performance of doped spinel cathodes and identify the governing material properties for controlling the discharging performance.

ACS Style

Guanyu Wang; Tom Fearn; Tengyao Wang; Kwang-Leong Choy. Insight Gained from Using Machine Learning Techniques to Predict the Discharge Capacities of Doped Spinel Cathode Materials for Lithium‐Ion Batteries Applications. Energy Technology 2021, 9, 2100053 .

AMA Style

Guanyu Wang, Tom Fearn, Tengyao Wang, Kwang-Leong Choy. Insight Gained from Using Machine Learning Techniques to Predict the Discharge Capacities of Doped Spinel Cathode Materials for Lithium‐Ion Batteries Applications. Energy Technology. 2021; 9 (5):2100053.

Chicago/Turabian Style

Guanyu Wang; Tom Fearn; Tengyao Wang; Kwang-Leong Choy. 2021. "Insight Gained from Using Machine Learning Techniques to Predict the Discharge Capacities of Doped Spinel Cathode Materials for Lithium‐Ion Batteries Applications." Energy Technology 9, no. 5: 2100053.

Communication
Published: 02 March 2021 in Chemical Communications
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A miniaturised electrochemical sensor integrating a molecularly imprinted silica/graphene oxide hybrid with non-equilibrium pulse amperometry for the fast quantification of free and bound toxins.

ACS Style

Antonio Ruiz-Gonzalez; Adam J. Clancy; Kwang-Leong Choy. Rapid detection of free and bound toxins using molecularly imprinted silica/graphene oxide hybrids. Chemical Communications 2021, 57, 4043 -4046.

AMA Style

Antonio Ruiz-Gonzalez, Adam J. Clancy, Kwang-Leong Choy. Rapid detection of free and bound toxins using molecularly imprinted silica/graphene oxide hybrids. Chemical Communications. 2021; 57 (33):4043-4046.

Chicago/Turabian Style

Antonio Ruiz-Gonzalez; Adam J. Clancy; Kwang-Leong Choy. 2021. "Rapid detection of free and bound toxins using molecularly imprinted silica/graphene oxide hybrids." Chemical Communications 57, no. 33: 4043-4046.

Short communication
Published: 12 January 2021 in Materials Letters
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Current technologies on conductive carbon aerogels are merely for application of super-capacitors, anodes of lithium ion batteries and electrocatalysts. To our best knowledge, carbon nanofibre (CNF) aerogels in biomedical application of chronic wound monitoring have not been reported yet. In this paper, we proposed a chronic wounds pH sensor, which is based on 3D free-standing conductive CNF aerogel derived from pyrolyzed bacterial cellulose (p-BC) as conducting substrate and it is incorporated with flexible and proton-selective PDMS/PANI composite. The resulted p-BC/PDMS/PANI nanocomposite is soft, flexible, and can exhibit near Nernst limit pH sensitivity (~−50.4 mV/pH) in pH buffer solution, and −29 mV/pH in in vitro simulated wound fluid. This renders its applications in flexible bio-sensors and smart wound dressings.

ACS Style

Manni Yang; Kwang-Leong Choy. A nature-derived, flexible and three dimensional (3D) nano-composite for chronic wounds pH monitoring. Materials Letters 2021, 288, 129335 .

AMA Style

Manni Yang, Kwang-Leong Choy. A nature-derived, flexible and three dimensional (3D) nano-composite for chronic wounds pH monitoring. Materials Letters. 2021; 288 ():129335.

Chicago/Turabian Style

Manni Yang; Kwang-Leong Choy. 2021. "A nature-derived, flexible and three dimensional (3D) nano-composite for chronic wounds pH monitoring." Materials Letters 288, no. : 129335.

Review
Published: 24 June 2020 in Sustainability
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Kesterite Cu2ZnSnS4 (CZTS) has attracted attention as an earth-abundant alternative to commercially successful CIGS solar cells. CZTS exhibits decent optoelectrical properties while having excellent stability on top of being an earth-abundant, low-cost and non-toxic material. Therefore, in recent years, there has been a significant research effort to develop CZTS-based devices. The efficiency of CZTS solar cells reached 12.6% in 2013, and this was a remarkable achievement at the time. However, the efficiency of these devices has been stagnant since then while emerging technologies, most notably perovskite solar cells, keep breaking record after record. Currently, CZTS research focuses on discovering the secrets of material properties that hinder the efficiency of CZTS solar cells while branching out to develop alternative applications for this material. In this review, we summarize the interesting properties of CZTS as well as its promising applications, which include thin-film solar cells, charge-transfer layers in perovskite solar cells, and photoelectrochemical water splitting while briefly commenting on its other possible applications.

ACS Style

Ahmet Nazligul; Mingqing Wang; Kwang Choy. Recent Development in Earth-Abundant Kesterite Materials and Their Applications. Sustainability 2020, 12, 5138 .

AMA Style

Ahmet Nazligul, Mingqing Wang, Kwang Choy. Recent Development in Earth-Abundant Kesterite Materials and Their Applications. Sustainability. 2020; 12 (12):5138.

Chicago/Turabian Style

Ahmet Nazligul; Mingqing Wang; Kwang Choy. 2020. "Recent Development in Earth-Abundant Kesterite Materials and Their Applications." Sustainability 12, no. 12: 5138.

Full paper
Published: 22 June 2020 in Macromolecular Bioscience
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Bacterial cellulose (BC) is a natural material produced by Acetobacter xylinum , widely used in wound dressings due to the high water‐holding capacity and great mechanical strength. In this paper, a novel antimicrobial dressing made from BC/methylglyoxal (MGO) composite with a dip‐coating method inspired by naturally antimicrobial Manuka honey is proposed, which to our best knowledge, has not yet to be reported. Characterizations by scanning electron microscope and atomic force microscopy show the interconnected nanostructure of BC and MGO and increase surface roughness of the BC/MGO composite. Thermal analysis indicates high temperature stability of both BC and BC/MGO, while compared with BC, BC/MGO exhibits slightly weaker thermal stability possibly due to reduction of hydrogen bonding and increase of crystallinity. Mechanical test confirms the strong mechanical property of BC and BC/MGO nanocomposite. From the disk diffusion antimicrobial test, the BC/MGO nanocomposite with highest MGO concentration (4%) shows great zone inhibition diameter (around 14.3, 12.3, 17.1, and 15.5 mm against Micrococcus luteus , Pseudomonas aeruginosa , Staphylococcus aureus , and Escherichia coli ). Compared with other antimicrobial wound dressing composite materials, the proposed BC/MGO nanocomposite has among the greatest antimicrobial property against broad‐spectrum bacteria, making it a promising antimicrobial dressing in chronic wounds care.

ACS Style

Manni Yang; John Ward; Kwang‐Leong Choy. Nature‐Inspired Bacterial Cellulose/Methylglyoxal (BC/MGO) Nanocomposite for Broad‐Spectrum Antimicrobial Wound Dressing. Macromolecular Bioscience 2020, 20, e2000070 .

AMA Style

Manni Yang, John Ward, Kwang‐Leong Choy. Nature‐Inspired Bacterial Cellulose/Methylglyoxal (BC/MGO) Nanocomposite for Broad‐Spectrum Antimicrobial Wound Dressing. Macromolecular Bioscience. 2020; 20 (8):e2000070.

Chicago/Turabian Style

Manni Yang; John Ward; Kwang‐Leong Choy. 2020. "Nature‐Inspired Bacterial Cellulose/Methylglyoxal (BC/MGO) Nanocomposite for Broad‐Spectrum Antimicrobial Wound Dressing." Macromolecular Bioscience 20, no. 8: e2000070.

Article
Published: 17 May 2020 in Journal of the American Ceramic Society
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Coefficient of thermal expansion (CTE) of a solid material plays a critical role for a variety of high temperature applications such as thermal barrier coating (TBC) systems during the thermal cycling process. Ceramics contain ionic bonds; hence they tend to exhibit lower CTE values than alloys/metals. Developing new ceramic thermal barrier materials using promising dopants and compositions that have higher CTE values than the conventional 6‐8 wt.% Y2O3 stabilized ZrO2 (8YSZ) will contribute to the decrease in thermal expansion mismatch between a typical ceramic 8YSZ (10~11×10‐6 °C‐1) top coat and a metal alloy based bond coat such as NiCrAlY (14~17×10‐6 °C‐1),1, 2 which is highly desirable. This work reports design, modelling, synthesis, and characterization of promising new compositions based on Dy3+, Al3+ and Ce4+ doped YSZ that consist of the tetragonal structure and have an enhanced thermal expansion than 8YSZ. The intrinsic CTE at the atomic level has been investigated via molecular dynamics (MD) simulation. The atomic scale analysis provides new insights into the enhanced doping effects of multiple trivalent and tetravalent cations on the lattice structure, lattice energy and thermal expansion in ZrO2. The calculated lattice energy becomes smaller with the incorporation of Dy3+, Al3+, and Ce4+ ions, which corresponds strongly to the increase in CTE. The crystalline size is reduced due to the incorporation of the Al3+ and Ce4+, whereas the sintering resistance is enhanced ascribed to the addition of Dy3+ and Al3+. Doping Dy3+, Al3+, and Ce4+ cations to YSZ increased the CTE value of YSZ and for Dy0.03Y0.075Zr0.895O1.948, the CTE is 12.494×10‐6 °C‐1 at 900°C, which has an 11% increase, as compared with that of 8YSZ.

ACS Style

Liu Qu; Kwang‐Leong Choy; Richard Wheatley. Enhanced doping effects of multielement on anisotropic thermal expansion in ZrO 2 with new compositions. Journal of the American Ceramic Society 2020, 103, 5881 -5890.

AMA Style

Liu Qu, Kwang‐Leong Choy, Richard Wheatley. Enhanced doping effects of multielement on anisotropic thermal expansion in ZrO 2 with new compositions. Journal of the American Ceramic Society. 2020; 103 (10):5881-5890.

Chicago/Turabian Style

Liu Qu; Kwang‐Leong Choy; Richard Wheatley. 2020. "Enhanced doping effects of multielement on anisotropic thermal expansion in ZrO 2 with new compositions." Journal of the American Ceramic Society 103, no. 10: 5881-5890.

Communication
Published: 21 April 2020 in Advanced Materials
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Flexible devices are garnering substantial interest owing to their potential for wearable and portable applications. Here, flexible and self‐powered photodetector arrays based on all‐inorganic perovskite quantum dots (QDs) are reported. CsBr/KBr‐mediated CsPbBr3 QDs possess improved surface morphology and crystallinity with reduced defect densities, in comparison with the pristine ones. Systematic material characterizations reveal enhanced carrier transport, photoluminescence efficiency, and carrier lifetime of the CsBr/KBr‐mediated CsPbBr3 QDs. Flexible photodetector arrays fabricated with an optimum CsBr/KBr treatment demonstrate a high open‐circuit voltage of 1.3 V, responsivity of 10.1 A W−1, specific detectivity of 9.35 × 1013 Jones, and on/off ratio up to ≈104. Particularly, such performance is achieved under the self‐powered operation mode. Furthermore, outstanding flexibility and electrical stability with negligible degradation after 1600 bending cycles (up to 60°) are demonstrated. More importantly, the flexible detector arrays exhibit uniform photoresponse distribution, which is of much significance for practical imaging systems, and thus promotes the practical deployment of perovskite products.

ACS Style

Kai Shen; Hao Xu; Xiao Li; Jian Guo; Sanjayan Sathasivam; Mingqing Wang; Aobo Ren; Kwang Leong Choy; Ivan P. Parkin; Zhengxiao Guo; Jiang Wu. Flexible and Self‐Powered Photodetector Arrays Based on All‐Inorganic CsPbBr 3 Quantum Dots. Advanced Materials 2020, 32, e2000004 .

AMA Style

Kai Shen, Hao Xu, Xiao Li, Jian Guo, Sanjayan Sathasivam, Mingqing Wang, Aobo Ren, Kwang Leong Choy, Ivan P. Parkin, Zhengxiao Guo, Jiang Wu. Flexible and Self‐Powered Photodetector Arrays Based on All‐Inorganic CsPbBr 3 Quantum Dots. Advanced Materials. 2020; 32 (22):e2000004.

Chicago/Turabian Style

Kai Shen; Hao Xu; Xiao Li; Jian Guo; Sanjayan Sathasivam; Mingqing Wang; Aobo Ren; Kwang Leong Choy; Ivan P. Parkin; Zhengxiao Guo; Jiang Wu. 2020. "Flexible and Self‐Powered Photodetector Arrays Based on All‐Inorganic CsPbBr 3 Quantum Dots." Advanced Materials 32, no. 22: e2000004.

Journal article
Published: 21 March 2020 in Materials & Design
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Silicon (Si) has attracted attention for use in lithium ion batteries due to its high theoretical capacity and its natural abundance. However, significant change in the volume of Si electrodes during repeated cycles causes dramatic capacity degradation and reduces the benefits of its attractive qualities. Here, it is reported for the first time that a derivative of natural spider silk is effective for retaining the capacity and decreasing the volume expansion of Si for use in Li-ion batteries as electrodes. Relative to the Si-electrode with polyvinylidene fluoride (SPVDF), the Si-electrode containing binder with the dissolved spider silk (SWS) cells achieved significant enhanced capacities with cycling stability during repeated cycles. The SWS electrode at 250 mA g −1 showed the discharge/charge capacities of 3642/1938 mAh g−1 at 1st cycle, 1789/1541 mAh g−1 at 2nd cycle and then reduced to 1142/1054 mAh g−1 at the 5th cycle. However, the capacities of the SPVDF electrode were 3903/2694 mAh g−1, 1455/1211 mAh g−1, and 458/435 mAh g−1. Furthermore, the discharge capacity of SWS was 333 mAh g−1 at the 38th cycle, but that of SPVDF showed 323 mAh g−1 at the 7th cycle. Such superior performance with good cycling ability may be attributed to the unique properties of spider silk: the folded crystal layer with semi-amorphous structure, the superior properties of viscosity and adhesion, and the close stacking by the protein blocks as well as the side chain R-group of crystal β-sheet. The combination of these characteristics was able to restrain the deleterious change in the volume of Si materials substantially, and to provide superior electrochemical characteristics of lithium ions.

ACS Style

DongWoong Choi; Kwang Leong Choy. Spider silk binder for Si-based anode in lithium-ion batteries. Materials & Design 2020, 191, 108669 .

AMA Style

DongWoong Choi, Kwang Leong Choy. Spider silk binder for Si-based anode in lithium-ion batteries. Materials & Design. 2020; 191 ():108669.

Chicago/Turabian Style

DongWoong Choi; Kwang Leong Choy. 2020. "Spider silk binder for Si-based anode in lithium-ion batteries." Materials & Design 191, no. : 108669.

Journal article
Published: 24 September 2019 in Molecules
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Perovskite solar cells (PSCs) have achieved tremendous success within just a decade. This success is critically dependent upon compositional engineering, morphology control of perovskite layer, or contingent upon high-temperature annealed mesoporous TiO2, but quantitative analysis of the role of facile TiCl4 treatment and thickness control of the compact TiO2 layer has not been satisfactorily undertaken. Herein, we report the facile thickness control and post-treatment of the electron transport TiO2 layer to produce highly efficient planar PSCs. TiCl4 treatment of TiO2 layer could remove the surface trap and decrease the charge recombination in the prepared solar cells. Introduction of ethanol into the TiCl4 aqueous solution led to further improved open-circuit voltage and short-circuit current density of the related devices, thus giving rise to enhanced power conversion efficiency (PCE). After the optimal TiCl4 treatment, PCE of 16.42% was achieved for PSCs with TiCl4 aqueous solution-treated TiO2 and 19.24% for PSCs with TiCl4 aqueous/ethanol solution-treated TiO2, respectively. This work sheds light on the promising potential of simple planar PSCs without complicated compositional engineering and avoiding the deposition and optimization of the mesoporous scaffold layer.

ACS Style

Weifu Sun; Kwang-Leong Choy; Mingqing Wang. The Role of Thickness Control and Interface Modification in Assembling Efficient Planar Perovskite Solar Cells. Molecules 2019, 24, 3466 .

AMA Style

Weifu Sun, Kwang-Leong Choy, Mingqing Wang. The Role of Thickness Control and Interface Modification in Assembling Efficient Planar Perovskite Solar Cells. Molecules. 2019; 24 (19):3466.

Chicago/Turabian Style

Weifu Sun; Kwang-Leong Choy; Mingqing Wang. 2019. "The Role of Thickness Control and Interface Modification in Assembling Efficient Planar Perovskite Solar Cells." Molecules 24, no. 19: 3466.

Journal article
Published: 26 June 2019 in Journal of Power Sources
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Solid state polymer electrolyte is a promising candidate for the next generation of all-solid-state lithium ion batteries due to its advantages of light weight, high stability to electrodes, non-flammable, sufficient mechanical strength to prevent lithium dendrite growth, and low cost. Here, through a facile and cost-effective route, two dimensional boron nitride (BN) is applied as an efficient additive in a polymer/salt hybrid electrolyte, which brings about high ionic conductivity, improved mechanical strength and intimate interfacial contact between the electrolyte and electrodes. A 1% BN addition into polymer/salt hybrid electrolyte membrane exhibits a high conductivity of 1.82 × 10−3 S/cm at room temperature. Indentation test shows the BN modified hybrid electrolyte possesses an enhanced hardness (4.99 MPa) and Young's modulus (0.133 GPa). The 1% BN modified hybrid electrolyte is demonstrated to effectively suppress the lithium dendrite growth during repeated striping and plating of lithium. As a result, the battery of lithium metal anode paired with LiFePO4 cathode and using the as-fabricated 1% BN enhanced polymer/salt hybrid electrolyte exhibits improved cycling performance with high Coulombic efficiency (over 98%).

ACS Style

Zhenyu Zhang; Ruiz Gonzalez Antonio; Kwang Leong Choy. Boron nitride enhanced polymer/salt hybrid electrolytes for all-solid-state lithium ion batteries. Journal of Power Sources 2019, 435, 226736 .

AMA Style

Zhenyu Zhang, Ruiz Gonzalez Antonio, Kwang Leong Choy. Boron nitride enhanced polymer/salt hybrid electrolytes for all-solid-state lithium ion batteries. Journal of Power Sources. 2019; 435 ():226736.

Chicago/Turabian Style

Zhenyu Zhang; Ruiz Gonzalez Antonio; Kwang Leong Choy. 2019. "Boron nitride enhanced polymer/salt hybrid electrolytes for all-solid-state lithium ion batteries." Journal of Power Sources 435, no. : 226736.

Journals
Published: 25 February 2019 in Journal of Materials Chemistry A
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ZnO nanoparticle decorated all-inorganic perovskite quantum dots exhibit improved photoresponse and long-term stability.

ACS Style

Kai Shen; Xiao Li; Hao Xu; Mingqing Wang; Xiao Dai; Jian Guo; Ting Zhang; Shibin Li; Guifu Zou; Kwang-Leong Choy; Ivan P. Parkin; Zhengxiao Guo; Huiyun Liu; Jiang Wu. Enhanced performance of ZnO nanoparticle decorated all-inorganic CsPbBr3 quantum dot photodetectors. Journal of Materials Chemistry A 2019, 7, 6134 -6142.

AMA Style

Kai Shen, Xiao Li, Hao Xu, Mingqing Wang, Xiao Dai, Jian Guo, Ting Zhang, Shibin Li, Guifu Zou, Kwang-Leong Choy, Ivan P. Parkin, Zhengxiao Guo, Huiyun Liu, Jiang Wu. Enhanced performance of ZnO nanoparticle decorated all-inorganic CsPbBr3 quantum dot photodetectors. Journal of Materials Chemistry A. 2019; 7 (11):6134-6142.

Chicago/Turabian Style

Kai Shen; Xiao Li; Hao Xu; Mingqing Wang; Xiao Dai; Jian Guo; Ting Zhang; Shibin Li; Guifu Zou; Kwang-Leong Choy; Ivan P. Parkin; Zhengxiao Guo; Huiyun Liu; Jiang Wu. 2019. "Enhanced performance of ZnO nanoparticle decorated all-inorganic CsPbBr3 quantum dot photodetectors." Journal of Materials Chemistry A 7, no. 11: 6134-6142.

Journals
Published: 21 February 2019 in Chemical Communications
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Infusion of solid perfluoroalkanes into polydimethylsiloxane gels provides a simple route to regenerating deicing surfaces, with low adhesion strength from the lower inherent cohesive energy of the perfluoroalkanes.

ACS Style

Arun Sandhu; Oliver J. Walker; Andrés Nistal; Kwang Leong Choy; Adam J. Clancy. Perfluoroalkane wax infused gels for effective, regenerating, anti-icing surfaces. Chemical Communications 2019, 55, 3215 -3218.

AMA Style

Arun Sandhu, Oliver J. Walker, Andrés Nistal, Kwang Leong Choy, Adam J. Clancy. Perfluoroalkane wax infused gels for effective, regenerating, anti-icing surfaces. Chemical Communications. 2019; 55 (22):3215-3218.

Chicago/Turabian Style

Arun Sandhu; Oliver J. Walker; Andrés Nistal; Kwang Leong Choy; Adam J. Clancy. 2019. "Perfluoroalkane wax infused gels for effective, regenerating, anti-icing surfaces." Chemical Communications 55, no. 22: 3215-3218.

Communication
Published: 31 January 2019 in Chemical Communications
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A CIGS-based photocathode combined with an earth abundant Co–S catalyst has demonstrated remarkable photoelectrochemical hydrogen generation in neutral electrolyte.

ACS Style

Mingqing Wang; Yung-Shan Chang; Chun-Wen Tsao; Mei-Jing Fang; Yung-Jung Hsu; Kwang-Leong Choy. Enhanced photoelectrochemical hydrogen generation in neutral electrolyte using non-vacuum processed CIGS photocathodes with an earth-abundant cobalt sulfide catalyst. Chemical Communications 2019, 55, 2465 -2468.

AMA Style

Mingqing Wang, Yung-Shan Chang, Chun-Wen Tsao, Mei-Jing Fang, Yung-Jung Hsu, Kwang-Leong Choy. Enhanced photoelectrochemical hydrogen generation in neutral electrolyte using non-vacuum processed CIGS photocathodes with an earth-abundant cobalt sulfide catalyst. Chemical Communications. 2019; 55 (17):2465-2468.

Chicago/Turabian Style

Mingqing Wang; Yung-Shan Chang; Chun-Wen Tsao; Mei-Jing Fang; Yung-Jung Hsu; Kwang-Leong Choy. 2019. "Enhanced photoelectrochemical hydrogen generation in neutral electrolyte using non-vacuum processed CIGS photocathodes with an earth-abundant cobalt sulfide catalyst." Chemical Communications 55, no. 17: 2465-2468.

Research article
Published: 11 December 2018 in PLoS ONE
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The present work investigates the process of frosting formation on arched copper samples with different surface temperatures, calculated the thickness of the frost layer by using the scale method, and analyzed frost lodging, melting, and other phenomena that appeared during the frost-formation process. The results showed that the frosting process on an arched surface can be divided into ice-film formation, rapid growth of the frost layer, and stable growth of the frost layer. Meanwhile, the phenomena of frost-branch breakage, lodging, and melting were observed. The surface temperature had a large effect on the frost formation and thickness of the frost layer, e.g., the formation time of the ice film on a surface at -5°C was the longest (~135 s), the frost layer formed on a surface at -20°C was the thickest (~660 μm). When microscopic observation of the frosting process was accompanied by calculation of the frost-layer thickness, it could be seen that the appearance of the frost branches was affected by the different thermal conductivities of the frost layers, undulating surface of the ice film, and temperature difference between the layers. The changes in the frost branches and the soft surface of the frost layer also affected the growth of the frost layer. The findings of this study are expected to provide guidelines for optimization of conventional defrosting methods.

ACS Style

Tingkun Chen; Qian Cong; Jingfu Jin; Kwang-Leong Choy. Experimental study on frost-formation characteristics on cold surface of arched copper sample. PLoS ONE 2018, 13, e0208721 .

AMA Style

Tingkun Chen, Qian Cong, Jingfu Jin, Kwang-Leong Choy. Experimental study on frost-formation characteristics on cold surface of arched copper sample. PLoS ONE. 2018; 13 (12):e0208721.

Chicago/Turabian Style

Tingkun Chen; Qian Cong; Jingfu Jin; Kwang-Leong Choy. 2018. "Experimental study on frost-formation characteristics on cold surface of arched copper sample." PLoS ONE 13, no. 12: e0208721.