Guo Xu, Liu Xing, Wang Menglong, Yan Junqing, Chen Yubin, Liu Shengzhong
Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.
International Research Center for Renewable Energy, State Key Laboratory for Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
Small. 2023 May;19(19):e2206695. doi: 10.1002/smll.202206695. Epub 2023 Feb 12.
Spinel cobalt oxide displays excellent photocatalytic performance, especially in solar driven water oxidation. However, the process of water reduction to hydrogen is considered as the Achilles' heel of solar water splitting over Co O owing to its low conduction band. Enhancement of the water splitting efficiency using Co O requires deeper insights of the carrier dynamics during water splitting process. Herein, the carrier dynamic kinetics of colloidal Co O quantum dots-Pt hetero-junctions is studied, which mimics the hydrogen reduction process during water splitting. It is showed that the quantum confinement effect induced by the small QD size raised the conduction band edge position of Co O QDs, so that the ligand-to-metal charge transfer from 2p state of oxygen to 3d state of Co occurs, which is necessary for overall water splitting and cannot be achieved in Co O bulk crystals. The findings in this work provide insights of the photocatalytic mechanism of Co O catalysts and benefit rational design of Co O -based photocatalytic systems.
尖晶石钴氧化物表现出优异的光催化性能，尤其是在太阳能驱动的水氧化方面。然而，由于其导带较低，水还原为氢气的过程被认为是氧化钴光解水的致命弱点。利用氧化钴提高水分解效率需要更深入了解水分解过程中的载流子动力学。在此，研究了胶体氧化钴量子点-铂异质结的载流子动力学，其模拟了水分解过程中的氢还原过程。结果表明，小量子点尺寸引起的量子限域效应提高了氧化钴量子点的导带边缘位置，从而发生了从氧的2p态到钴的3d态的配体到金属的电荷转移，这是整体水分解所必需的，而在氧化钴体晶体中无法实现。这项工作的发现为氧化钴催化剂的光催化机理提供了见解，并有助于基于氧化钴的光催化系统的合理设计。
