Calcium hafnate perovskite from an insulator to a semiconductor for photovoltaic and photocatalytic hydrogen production from water splitting applications

Abstract

Converting solar energy into electrical or chemical energy is an effective solution to produce clean and less expensive energy. Based on this, this paper sheds new light on the neglected photovoltaic and photocatalytic hydrogen production from water splitting applications of lead-free calcium hafnate perovskite (CHO) by converting CHO from an insulator to a semiconductor by doping CHO with chalcogens. Moreover, the intrinsic oxygen vacancy (Vo) defect in oxide materials was taken into consideration in our calculations based on DFT using LDA + mBJ approximation. It was found that when CHO was doped with chalcogens impurities the forbidden band was decreased with the increase of chalcogens impurities concentrations in CHO, especially when Tellurium (Te) and Selenium (Se) substitutions meet a Vo defect in CHO due to the increases to its charge carries' mobility. Furthermore, when chalcogens impurities meet a Vo defect in CHO the edge's absorption extends in the visible spectrum which is a basic requirement for photovoltaic and photocatalyst devices.