Artificial Photosynthesis on TiO2-Passivated InP Nanopillars

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• 作者：Jing Qiu ; Guangtong Zeng ; Mai-Anh Ha ; Mingyuan Ge ; Yongjing Lin ; Mark Hettick ; Bingya Hou ; Anastassia N. Alexandrova ; Ali Javey ; Stephen B. Cronin
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：September 9, 2015
• 年：2015
• 卷：15
• 期：9
• 页码：6177-6181
• 全文大小：338K
• ISSN：1530-6992

文摘

Here, we report photocatalytic CO₂ reduction with water to produce methanol using TiO₂-passivated InP nanopillar photocathodes under 532 nm wavelength illumination. In addition to providing a stable photocatalytic surface, the TiO₂-passivation layer provides substantial enhancement in the photoconversion efficiency through the introduction of O vacancies associated with the nonstoichiometric growth of TiO₂ by atomic layer deposition. Plane wave-density functional theory (PW-DFT) calculations confirm the role of oxygen vacancies in the TiO₂ surface, which serve as catalytically active sites in the CO₂ reduction process. PW-DFT shows that CO₂ binds stably to these oxygen vacancies and CO₂ gains an electron (鈭?.897e) spontaneously from the TiO₂ support. This calculation indicates that the O vacancies provide active sites for CO₂ absorption, and no overpotential is required to form the CO₂^{鈥?/sup> intermediate. The TiO₂ film increases the Faraday efficiency of methanol production by 5.7脳 to 4.79% under an applied potential of 鈭?.6 V vs NHE, which is 1.3 V below the Eo(CO₂/CO₂鈥?/sup>) = 鈭?.9 eV standard redox potential. Copper nanoparticles deposited on the TiO₂ act as a cocatalyst and further improve the selectivity and yield of methanol production by up to 8-fold with a Faraday efficiency of 8.7%.}