CeVO₄/CeO₂ Heterostructure-Supported Co Nanoparticles for Photocatalytic H₂ Production from Ammonia Borane under Visible Light

Abstract

The effective separation of electron–hole pairs of the support plays an important role in improving the activity of a supported photocatalyst under visible-light irradiation. Herein, we constructed a CeVO4/CeO2 type-II heterojunction with strong electronic interactions and rich oxygen vacancies due to only minor lattice mismatch by the significantly changed crystal structure of two materials in the absence of an additional structure-directing agent in the calcination process. The CeVO4/CeO2 nanocomposites as supports for Co nanoparticles (NPs) exhibited remarkable photocatalytic performance for H2 evolution from ammonia borane (NH3BH3) at 25 °C. Experimental results clearly showed that a Co catalyst with a CeVO4/CeO2 nanocomposite in a 2:1 mol ratio had the best photocatalytic performance with a total turnover frequency (TOF) value of 90.9 min–1. The structure characterizations indicated that the excellent H2 evolution performance was attributed to the formation of type-II heterojunction with strong electronic interactions and rich oxygen vacancies between CeVO4 and CeO2 by the conversion of the crystal structure of two materials in the calcination process, which accelerated the separation and migration of electron–hole pairs, leading to increased electron density of Co NPs. This work underlines the importance of heterojunction construction and paves a way to designing heterostructure catalysts for photocatalytic H2 production from NH3BH3 under light irradiation with a wavelength range of 420–780 nm.