Enhancing photocatalytic activity for hydrogen production and pollutant degradation by modifying tetragonal ZrO2 with monolayers slab surface of BiVO4, Ag3PO4, SrTiO3 and WO3: A first-principles study

Abstract

Semiconductor-based photocatalysis has received increasing attention in energy storage and environmental remediation process due to the abundant solar energy. For this purpose, heterostructures of ZrO2 coupled with BiVO4, Ag3PO4, SrTiO3 and WO3 monolayers are designed to examine their potential applications in hydrogen production and degradation of pollutants using density functional theory (DFT) + U method for the first time. The results revealed that the calculated band gaps of the heterostructures are reduced compared to the pure ZrO2, which favour redshift absorption. A type-I band alignment is attained for the BiVO4/ZrO2, Ag3PO4/ZrO2 and WO3/ZrO2 heterostructures. More importantly, a type-II staggered band alignment formed in the SrTiO3/ZrO2 heterostructure restrained the charge recombination rate of photoinduced charge carriers, as well as enhancing the photocatalytic activity. In particular, suitable band alignment of SrTiO3/ZrO2 with enough driving forces for charge carrier transfer show overall water splitting and degradation of pollutant in which SrTiO3 acted as charge separation centre. Furthermore, h+, and radicals played a major role in the photocatalysis process of the SrTiO3/ZrO2 heterostructure. These results reveal that the ZrO2 acts as an oxidation site so that better access of electron acceptor to the interface is a significant factor that improves the photocatalytic activity of SrTiO3/ZrO2 heterostructure towards H2 evolution.