A Type-I Heterojunction by Anchoring Ultrafine Cu₂O on Defective TiO₂ Framework for Efficient Photocatalytic H₂ Production

Abstract

The metal–organic framework (MOF) contains abundant metal ions and organic ligands, and is an excellent self-sacrificial template or precursor for further assembly of functional composites. Herein, MOF-derived defective TiO 2 anchored by ultrafine Cu 2 O nanoparticles has been successfully prepared. In situ formation of type-I heterojunctions between defective TiO 2 and ultrafine Cu 2 O nanoparticles and their application in photocatalytic H 2 evolution were demonstrated. Series of composites with varying amounts of Cu 2 O from 1% to 10% were synthesized. 5 wt % Cu 2 O loading leads to a H 2 generation activity of 4.81 mmol g –1 h –1 under UV–visible light, which is about 3.2 times larger than that of MOF-derived defective TiO 2 (1.49 mmol g –1 h –1 ). It is found that the existence of Ti 3+ and O v defects in the prepared Cu 2 O/D-TiO 2 (defective TiO 2 ) introduces a new local energy level in the forbidden band, which is responsible for effective charge separation. The uniform distribution of Cu 2 O nanoparticles in defective TiO 2 enables close surface contact, enhanced visible light absorption, and electron-transfer efficiency through the formation of heterojunction. This work provides valuable guidelines for exploiting high-performance MOF-derived photocatalysts for the photocatalytic H 2 evolution.