Artificial Photosynthesis on TiO2-Passivated InP Nanopillars

作者：Qiu Jing; Zeng Guangtong; Ha Mai Anh; Ge Mingyuan; Lin Yongjing; Hettick Mark; Hou Bingya; Alexandrova Anastassia N; Javey Ali; Cronin Stephen B^*

来源：Nano Letters, 2015, 15(9): 6177-6181.

DOI：10.1021/acs.nanolett.5b02511

• Photoelectrochemical
• InP
• copper
• CO2 reduction
• TiO2-passivation
• methanol

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 (-0.897e) 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- intermediate. The TiO2 film increases the Faraday efficiency of methanol production by 5.7X to 4.79% under an applied potential of -0.6 V vs NHE, which is 1.3 V below the E degrees(CO2/CO2-) = -1.9 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%.

• 出版日期2015-9