Cu–In Co‐Doped CdS Enhances Photocatalytic Nitrate Reduction to Ammonia in Pure Water Systems

The development of low‐cost and highly efficient catalysts for nitrate reduction to ammonia without sacrificial reagents in pure water systems remains a major challenge in the field of photocatalytic nitrate reduction. By regulating the electronic structure and introducing metal ions stepwise through water bath and photodeposition methods, a promising modification strategy is provided to enhance the intrinsic activity of functional catalytic materials. This study explores the interaction between copper and indium co‐doped cadmium sulfide. Notably, co‐doping with Cu and In not only regulates the electronic structure but also optimizes the electronic properties of CdS. Compared with pure CdS samples, the interaction between Cu, In, and CdS in this catalyst is significantly enhanced. Under pure water conditions without sacrificial reagents, the NH 4 + production rate reaches 38.26 μmol g −1 h −1 , which is approximately six times higher than that of pure CdS. Additionally, this catalyst exhibits good cycling stability and durability. Experimental and theoretical analyses indicate that the doping of In can bring the d‐band center of Cu closer to the Fermi level, and this microstructure modification further enhances the adsorption and dissociation ability of NO 3 − . This research provides a practical strategy for the design of efficient photocatalytic nitrate reduction under mild conditions.