(Cu, Ag)-DOPED ZnS WITH WIDE VISIBLE LIGHT RANGE ABSORPTION FOR WATER SPLITTING: A THEORETICAL AND EXPERIMENTAL STUDY

Abstract

Photocatalytic water splitting using a semiconductor photocatalyst is a promising process for direct solar energy conversion. In this study, the feasibility of the photocatalytic H2 evolution on (Cu, Ag)- doped ZnS catalysts under visible light irradiation has been investigated by using first-principles density functional theory calculations and experimental studies. The present results reveal that (Cu, Ag)-doped ZnS structures have relatively small formation energy, implying that they are more easily obtained in experiment. Moreover, the absorption is enhanced obviously in the visible-light region for (Cu, Ag)-doped ZnS, but their energy levels are still suitable for water splitting to generate H2, which means that (Cu, Ag)-doped ZnS structures are promising candidate photocatalyst materials for H2 production driven by visible light. ZnS and (Cu, Ag)-doped ZnS were prepared using chemical precipitation method. (Cu, Ag)-doped ZnS samples showed an improved photocatalytic activity compared with undoped ZnS. Ag-doped ZnS (0.15 g L[Formula: see text] has the highest hydrogen evolution rate of 794.6 [Formula: see text]mol[Formula: see text] h[Formula: see text] [Formula: see text] g[Formula: see text] at pH 3 (0.1 M Na2S solution as a sacrificing agent).