Post‐Addition of Metal Species over CdIn ₂ S ₄ Micro‐Pyramids/Nanosheets for Photocatalytic Hydrogen Production and Benzylamine Valorization

Photocatalysis is a sustainable technology that can be used to produce fuels and chemicals. Cadmium indium sulfide (CdIn 2 S 4 ) is a promising photocatalyst due to its high efficiency and ability to absorb sunlight. CdIn 2 S 4 is one of the few semiconductors that can absorb up to 620 nm which represents 21% of the photons in solar illumination. Metal species can enhance the photocatalytic performance of CdIn 2 S 4 through increasing charge separation and acting as catalytic sites for redox reactions. Herein, CdIn 2 S 4 micropyramids/nanosheets were synthesized via a solvothermal synthesis and plasma‐treated. Different metal species (atomic/small nanoclusters) were post‐added to them via the deposition–precipitation route. The plasma‐treated CdIn 2 S 4 achieved an enhanced H 2 production rate of 985 μmol g −1 h −1 in the presence of benzylamine under visible light irradiation ( λ > 400 nm) compared to untreated CdIn 2 S 4 (667 μmol g −1 h −1 ). The introduction of Au and Ru species further enhanced the H 2 production rate to ~8.1 times (7968 μmol g −1 h −1 ) and 6.7 times (6632 μmol g −1 h −1 ), respectively, compared to the plasma‐treated CdIn 2 S 4 . The plasma‐treated Au‐CdIn 2 S 4 displayed photocatalytic oxidative coupling of benzylamine into N ‐benzylidenebenzylamine (a value‐added product) with high selectivity >92% at a rate of 1102 μmol g −1 h −1 under visible light irradiation ( λ > 400 nm).