Synergism of the Plasmonic Effect and Schottky Junction to Effectively Facilitate Photocatalytic CO<sub>2</sub> Reduction of Bi<sub>4</sub>O<sub>5</sub>I<sub>2</sub>@Cu
Qingling Huang, Jie Lin, Deshuai Yang, Yingfei Hu, Guobing Zhou, Wei Li, Jianqiang Hu, Zhen Yang
Abstract
To achieve highly efficient photocatalytic CO 2 reduction, it is crucial to attain efficient light absorption across a wide spectral range and rapid separation of photogenerated electrons and holes. Herein, we synthesize a Bi 4 O 5 I 2 @Cu photocatalyst by the in situ photodeposition of Cu nanoparticles (NPs) onto Bi 4 O 5 I 2 micron flowers (MFs) assembled from numerous nanosheets. The hierarchical hybrid of Bi 4 O 5 I 2 @Cu combines two distinct merits: the surface plasmon resonance (SPR) effect induced by Cu NPs and the Bi 4 O 5 I 2 /Cu Schottky junction. Specifically, the SPR effect of Cu NPs can broaden the range of light absorption to the near-infrared, resulting in the generation of hot electrons. Some of these hot electrons then migrate across the Schottky barrier of Bi 4 O 5 I 2 /Cu, injecting into the conduction band (CB) of Bi 4 O 5 I 2 MFs. This process increases the electron density in the CB of Bi 4 O 5 I 2, which is beneficial for the CO 2 photoreduction. On the other hand, the Bi 4 O 5 I 2 /Cu Schottky heterojunction effectively prevents the electron backflow from Bi 4 O 5 I 2 to Cu and facilitates the transfer of photogenerated holes in the valence band (VB) of Bi 4 O 5 I 2 into Cu NPs for H 2 O oxidation, as supported by density functional theory (DFT) calculations, confirming the achievement of efficient spatial separation and migration of charge carriers. Under visible light irradiation without any sacrificial reagent, Bi 4 O 5 I 2 @Cu-0.5 with an optimal loading of Cu NPs demonstrates a significantly enhanced CO production rate of 7.34 μmol g –1 h –1, which is approximately 13.1 times higher than that of the bare Bi 4 O 5 I 2 MFs and also surpasses those of the most reported bismuth oxyhalide-based and plasmon-based photocatalysts. Therefore, this work offers a new strategy for the development of excellent photocatalysts by the synergistic utilization of the plasmonic effect and Schottky junction.