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Your search keyword '"Sheppard, Leigh R"' showing total 21 results
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21 results on '"Sheppard, Leigh R"'

7. Manipulation of Charge Transport by Metallic V 13 O 16 Decorated on Bismuth Vanadate Photoelectrochemical Catalyst

Author

Ren, Hangjuan, primary, Dittrich, Thomas, additional, Ma, Hongyang, additional, Hart, Judy N., additional, Fengler, Steffen, additional, Chen, Sheng, additional, Li, Yibing, additional, Wang, Yu, additional, Cao, Fuyang, additional, Schieda, Mauricio, additional, Ng, Yun Hau, additional, Xie, Zhirun, additional, Bo, Xin, additional, Koshy, Pramod, additional, Sheppard, Leigh R., additional, Zhao, Chuan, additional, and Sorrell, Charles C., additional

Published
2019
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10. The Formation of Defect-Pairs for Highly Efficient Visible-Light Catalysts

Author

Sun, Qingbo, Cortie, David, Zhang, Shaoyang, Frankcombe, Terry J, She, Guangwei, Gao, Jie, Sheppard, Leigh R, Hu, Wanbiao, Chen, Hua, Zhuo, Shangjun, Chen, Dehong, Withers, Ray L, McIntyre, Garry, Yu, Dehong, Shi, Wensheng, Liu, Yun, Sun, Qingbo, Cortie, David, Zhang, Shaoyang, Frankcombe, Terry J, She, Guangwei, Gao, Jie, Sheppard, Leigh R, Hu, Wanbiao, Chen, Hua, Zhuo, Shangjun, Chen, Dehong, Withers, Ray L, McIntyre, Garry, Yu, Dehong, Shi, Wensheng, and Liu, Yun

Abstract

Highly efficient visible-light catalysts are achieved through forming defect-pairs in TiO2 nanocrystals. This study therefore proposes that fine-tuning the chemical scheme consisting of charge-compensated defect-pairs in balanced concentrations is a key missing step for realizing outstanding photocatalytic performance. This research benefits photocatalytic applications and also provides new insight into the significance of defect chemistry for functionalizing materials.

Published
2017

11. Bulk diffusion of niobium in single-crystal titanium dioxide

Author

Sheppard, Leigh R., Atanacio, Armand J., Bak, Tadeusz, Nowotny, Janusz, and Prince, Kathryn E.

Subjects
Diffusion -- Analysis, Mass spectrometry -- Analysis, Niobium -- Structure, Titanium dioxide -- Structure, Titanium dioxide -- Chemical properties, Chemicals, plastics and rubber industries
Abstract

The tracer diffusion coefficient for niobium in rutile Ti[O.sub.2] single crystals which could be applied to the processing of Nb-doped Ti[O.sub.2]-based semiconductors using solid-state reactions between [Nb.sub.2][O.sub.5] and Ti[O.sub.2] is reported.

Published
2007

13. The Formation of Defect‐Pairs for Highly Efficient Visible‐Light Catalysts

Author

Sun, Qingbo, primary, Cortie, David, additional, Zhang, Shaoyang, additional, Frankcombe, Terry J., additional, She, Guangwei, additional, Gao, Jie, additional, Sheppard, Leigh R., additional, Hu, Wanbiao, additional, Chen, Hua, additional, Zhuo, Shangjun, additional, Chen, Dehong, additional, Withers, Ray L., additional, McIntyre, Garry, additional, Yu, Dehong, additional, Shi, Wensheng, additional, and Liu, Yun, additional

Published
2017
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14. Chemical Synthesis and High-Pressure Reaction of Nb5+Monodoped Rutile TiO2Nanocrystals

Author

Sun, Qingbo, Huston, Larissa Q., Tang, Chunguang, Wei, Lingling, Sheppard, Leigh R., Chen, Hua, Frankcombe, Terry J., Bradby, Jodie E., and Liu, Yun

Abstract

Identifying the doping effects of extrinsic ions both during chemical reactions and in resultant products is important to deeply understand the associated material properties and to develop novel materials for practical applications. Here, we experimentally demonstrate the significant inhibitor effect of Nb5+dopants on the formation of rutile TiO2nanocrystals through dopant concentration-modified solvothermal reaction processes. A lower Nb5+doping level (≤9.09 atom %) is found to be more beneficial for the nucleation and growth of rutile Ti1 – 2x4+Tix3+Nbx5+O2nanocrystals while a higher one (>9.09 at.%) leads to the preferable formation of the anatase phase. At a pressure range of up to 30 GPa, the synthesized Nb5+monodoped rutile TiO2nanocrystals almost possess an equal slope in their respective plot of the pressure-dependent Raman frequency shifts and a similar structural transformation from rutile to baddeleyite-like (pressurization) and then to an α-PbO2-like phase (depressurization). They thus present a dopant concentration-independent high-pressure reaction behavior due to a small change in their average and local defect structures evidenced by the bond valence sum analysis and density functional theory calculations. This work not only emphasizes the key roles of dopants in material synthesis but also broadens insights into the intrinsic correlations between material properties and their specific local defects.

Published
2020
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18. Solute Diffusion of Platinum in Rutile Titanium Dioxide.

Author

Sheppard, Leigh R., Lamo, Marta Bello, Holik, John, Mayfield, Kirsty J., Nelson, David R., and Zhou, X. ‐ D.

Subjects
*PLATINUM, *TITANIUM dioxide, *RUTILE, *DIFFUSION, *TEMPERATURE
Abstract

195 Pt solute diffusion coefficients in undoped single-crystal rutile TiO2 have been determined parallel to the c-axis over the temperature range of 1073-1523 K and oxygen partial pressure of 101 kPa. This has yielded the following temperature dependence: [ABSTRACT FROM AUTHOR]

Published
2013
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21. Oriented epitaxial TiO 2 nanowires for water splitting.

Author

Hou W, Cortez P, Wuhrer R, Macartney S, Bozhilov KN, Liu R, Sheppard LR, and Kisailus D

Abstract

Highly oriented epitaxial rutile titanium dioxide (TiO 2 ) nanowire arrays have been hydrothermally grown on polycrystalline TiO 2 templates with their orientation dependent on the underlying TiO 2 grain. Both the diameter and areal density of the nanowires were tuned by controlling the precursor concentration, and the template surface energy and roughness. Nanowire tip sharpness was influenced by precursor solubility and diffusivity. A new secondary ion mass spectrometer technique has been developed to install additional nucleation sites in single crystal TiO 2 templates and the effect on nanowire growth was probed. Using the acquired TiO 2 nanowire synthesis knowhow, an assortment of nanowire arrays were installed upon the surface of undoped TiO 2 photo-electrodes and assessed for their photo-electrochemical water splitting performance. The key result obtained was that the presence of short and dispersed nanowire arrays significantly improved the photocurrent when the illumination intensity was increased from 100 to 200 mW cm -2 . This is attributed to the alignment of the homoepitaxially grown nanowires to the [001] direction, which provides the fastest charge transport in TiO 2 and an improved pathway for photo-holes to find water molecules and undertake oxidation. This result lays a foundation for achieving efficient water splitting under conditions of concentrated solar illumination.

Published
2017
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