High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes

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• 作者：Lite Zhou ; Chenqi Zhao ; Binod Giri ; Patrick Allen ; Xiaowei Xu ; Hrushikesh Joshi ; Yangyang Fan ; Lyubov V. Titova ; Pratap M. Rao
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：June 8, 2016
• 年：2016
• 卷：16
• 期：6
• 页码：3463-3474
• 全文大小：663K
• 年卷期：0
• ISSN：1530-6992

文摘

BiVO₄ has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO₄ photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO₄ coated onto Sb-doped SnO₂ (Sb:SnO₂) nanorod-arrays (Sb:SnO₂/BiVO₄ NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (η_abs × η_sep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest η_abs × η_sep efficiencies achieved to date at this voltage for nanowire-core/BiVO₄-shell photoanodes. Moreover, although WO₃ has recently been extensively studied as a core nanowire material for core/shell BiVO₄ photoanodes, the Sb:SnO₂/BiVO₄ NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO₂/BiVO₄ and WO₃/BiVO₄ heterojunctions, which indicate that Sb:SnO₂ is more favorable as a core material. These results indicate that integration of Sb:SnO₂ nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO₄ and related semiconductors closer to their theoretical potential.