Artificial Photosynthetic System with Spatial Dual Reduction Site Enabling Enhanced Solar Hydrogen Production

Abstract Although S‐scheme artificial photosynthesis shows promise for photocatalytic hydrogen production, traditional methods often overly concentrate on a single reduction site. This limitation results in inadequate redox capability and inefficient charge separation, which hampers the efficiency of the photocatalytic hydrogen evolution reaction. To overcome this limitation, a double S‐scheme system is proposed that leverages dual reduction sites, thereby preserving energetic photo‐electrons and holes to enhance apparent quantum efficiency. The design features a double S‐scheme junction consisting of CdS nanospheres decorated with anatase TiO 2 nanoparticles coupled with graphitic C 3 N 4 . The as‐prepared catalyst exhibits a hydrogen evolution rate of 26.84 mmol g −1 h −1 and an apparent quantum efficiency of 40.2% at 365 nm. This enhanced photocatalytic hydrogen evolution is ascribed to the efficient charge separation and transport induced by the double S‐scheme. Both theoretical calculations and comprehensive spectroscopy tests (both in situ and ex situ) affirm the efficient charge transport across the catalyst interface. Moreover, substituting the reduction‐type catalyst CdS with other similar sulfides like ZnIn 2 S 4 , ZnS, MoS 2 and In 2 S 3 further confirms the feasibility of the proposed double S‐scheme configuration. The findings provide a pathway to designing more effective double S‐scheme artificial photosynthetic systems, opening up fresh perspectives in enhancing photocatalytic hydrogen evolution performance.