Synthesis and Performance Evaluations of ZnCoS/ZnCdS with Twin Crystal Structure for Multifunctional Redox...

This protocol presents both the synthesis of the visible-light-responsive ZnCoS/ZnCdS with twin crystal structure photocatalyst and the photoredox reaction testing of its photocatalytic activity and selectivity in H2 evolution and benzaldehyde production. This ZnCoS/ZnCdS heterostructure integrates the mixed-phase junction advantage of ZnCdS semiconductor and the cocatalytic function of ZnCoS acting as an electron reservoir to facilitate the surface reaction. Notably, the existence of twin crystal structure within a ZnCdS semiconductor purportedly presents a nano-scaled twin superlattice configuration with an alternative arrangement of long-range-ordered twinned planes, which gives rise to a unique wurtzite/zinc blende (WZ/ZB) interphase junction. This interphase junction possesses an interfacial electrostatic field, resulting in excellent photoexcited charge carrier separation and transport to the specimen surface, hence facilitating redox reactions. We report a facile hydrothermal approach to prepare the visible-light-responsive ZnCoS/ZnCdS with twin crystal structure, where the ZnCoS plays a crucial role in capturing photoinduced electrons on the catalyst surface. UV-Vis diffuse reflectance spectroscopy and N2 physisorption measurement were conducted to determine the photoabsorption ability and surface area of the sample, respectively. A detailed setup of solar-driven H2 production coupled with benzyl alcohol oxidation and an online gas chromatography was demonstrated. The ZnCoS/ZnCdS exhibited an enormous enhancement in both H2 and benzaldehyde formation. The correlation between ZnCoS co-catalyst and WZ/ZB phase junctions of ZnCdS towards the photocatalytic behavior was systematically assessed. This casts a novel idea to optimize the design of dual-functional photocatalysts for multifarious energy applications.