Epitaxial facet junctions on TiO2 single crystals for efficient photocatalytic water splitting

• Published in: Energy & environmental science Vol. 11; no. 6; pp. 1444 - 1448
• Main Authors: Ai-Yong, Zhang, Wei-Yi, Wang, Jie-Jie Chen, Liu, Chang, Li, Qun-Xiang, Zhang, Xing, Wen-Wei, Li, Yang, Si, Han-Qing, Yu
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2018
• Subjects: Alignment; Anatase; Catalysis; Catalysts; Crystals; Density functional theory; Exposure; Homojunctions; Hydrogen production; Interfaces; Metal oxide semiconductors; Photochemicals; Quantum efficiency; Single crystals; Titanium dioxide; Water splitting
• DOI: 10.1039/c7ee03482b
• ISSN: 1754-5692

Metal oxide semiconductors with surface homojunctions characteristic of continuous band bending and well-defined epitaxial interfaces show amazing potential for photocatalytic applications. Herein, a new concept of facet junctions is proposed and validated according to the synergy between the co-exposed crystal facets of shape-tailored anatase TiO2 single crystals. By considering the atomic and electronic interactions between the co-exposed facets, our density functional theory calculations reveal the existence of type-II band alignment between the co-exposed {001} and {101} facets. This band alignment results in in situ construction of a facet junction to allow built-in facet-mediated carrier transfer. The self-constructed {101}/{001} facet junction, due to the effective carrier separation between different exposed facets, exhibits a significantly enhanced quantum efficiency and catalytic performance in photochemical hydrogen generation compared to TiO2 poly-crystals. These findings open a new horizon of facet junction-engineered nano-catalysts for more robust and efficient energy and environmental applications.