Solar-Driven H<sub>2sub>O<sub>2sub> Generation From H<sub>2sub>O and O<sub>2sub> Using Earth-Abundant Mixed-Metal Oxide@Carbon Nitride Photocatalysts
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- 作者：Ruirui Wang ; Kecheng Pan ; Dandan Han ; Jingjing Jiang ; Dr. Chengxiang Xiang ; Dr. Zhuangqun Huang ; Dr. Lu Zhang and Prof. Dr. Xu Xiang
- 刊名：ChemSusChem
- 出版年：2016
- 出版时间：September 8, 2016
- 年：2016
- 卷：9
- 期：17
- 页码：2470-2479
- 全文大小：1815K
- ISSN：1864-564X
文摘
Light-driven generation of H<sub>2sub>O<sub>2sub> only from water and molecular oxygen could be an ideal pathway for clean production of solar fuels. In this work, a mixed metal oxide/graphitic-C<sub>3sub>N<sub>4sub> (MMO@C<sub>3sub>N<sub>4sub>) composite was synthesized as a dual-functional photocatalyst for both water oxidation and oxygen reduction to generate H<sub>2sub>O<sub>2sub>. The MMO was derived from a NiFe-layered double hydroxide (LDH) precursor for obtaining a high dispersion of metal oxides on the surface of the C<sub>3sub>N<sub>4sub> matrix. The C<sub>3sub>N<sub>4sub> is in the graphitic phase and the main crystalline phase in MMO is cubic NiO. The XPS analyses revealed the doping of Fe<sup>3+sup> in the dominant NiO phase and the existence of surface defects in the C<sub>3sub>N<sub>4sub> matrix. The formation and decomposition kinetics of H<sub>2sub>O<sub>2sub> on the MMO@C<sub>3sub>N<sub>4sub> and the control samples, including bare MMO, C<sub>3sub>N<sub>4sub> matrix, Ni- or Fe-loaded C<sub>3sub>N<sub>4sub> and a simple mixture of MMO and C<sub>3sub>N<sub>4sub>, were investigated. The MMO@C<sub>3sub>N<sub>4sub> composite produced 63 μmol L<sup>−1sup> of H<sub>2sub>O<sub>2sub> in 90 min in acidic solution (pH 3) and exhibited a significantly higher rate of production for H<sub>2sub>O<sub>2sub> relative to the control samples. The positive shift of the valence band in the composite and the enhanced water oxidation catalysis by incorporating the MMO improved the light-induced hole collection relative to the bare C<sub>3sub>N<sub>4sub> and resulted in the enhanced H<sub>2sub>O<sub>2sub> formation. The positively shifted conduction band in the composite also improved the selectivity of the two-electron reduction of molecular oxygen to H<sub>2sub>O<sub>2sub>.