Preferential heteroatom substitution into ZnIn2S4 nanosheets boosts photocatalytic hydrogen production

Interior modification through preferential substitution of heteroatoms in 2D materials can rescue surface reactive sites for enhanced charge kinetics and photo-activity. Here, Ru and Ni heteroatoms were successfully incorporated in ZnIn2S4 (ZIS) nanosheets via a simple hydrothermal technique. Ru-ZIS photocatalysts exhibited improved photo–water splitting activity (26,400 µmol. h-1g-1) and good stability than that of Ni-ZIS and pristine ZIS under simulated sunlight, which may be related to the increase in reactive sites with Ru substitution, optimized adsorption-free energy of the reaction intermediates and charge kinetics. Ru substitution influenced Zn site availability and thus coordinated bonding with surrounding S ions. Ru-ZIS showed excellent hydrogen evolution performance and minimal change in Gibbs free energy (ΔGH, ~0 eV). By analyzing the density of states, both Ru and S sites had greater H* intermediate absorption abilities. This study elaborates on the effect of preferential heteroatom substitution on photocatalytic performance and has widespread applications.