Rational regulation of vacancy species to manage migration paths of carriers in MoS2/TiO2 heterojunctions for efficient photocatalytic H-2 generation

摘要

Photocatalytic water splitting to produce hydrogen (H-2), as one means to solve environ-mental pollution and energy shortage, is limited by the serious recombination of photo-generated electrons and holes, resulting in low solar energy conversion efficiency. Thus, steering the behaviors of charge carriers by rationally designing their transport pathway is essential, which can effectively suppress the recombination of electrons and holes. Herein, we designed a MoS2/TiO2 heterojunction with different vacancy species to manage the migration paths of photogenerated charge carriers. As demonstrated by experimental characterizations and density functional theory (DFT) calculations, oxygen and sulfur va-cancies can induce defect energy levels in heterostructures, which can capture photo-generated holes and electrons, respectively, resulting in substantially promoted charge separation efficiency and longer lifetime of electrons. As expected, the optimized photo-catalyst shows a stable H2 production rate of 1.41 mmol g(-1) h(-1), which is significantly better than that of the bare MoS2/TiO2 heterojunction. This finding informs the significance in rational design of the nanostructures for promoting the photocatalytic performance.(C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.