Enhanced photocatalyst performance by promoting carrier separation: CuNi2S4-ZnCdS nano-contact heterojunctions

The production of hydrogen via the photolysis of water represents a sustainable and environmentally benign approach to energy generation, which has the potential to mitigate energy shortages and environmental degradation. Nonetheless, the efficiency of photocatalysts is significantly limited by the effectiveness of charge carrier separation. Reducing the diffusion distance of these carriers can enhance their overall performance of the photocatalyst. In this context, a composite photocatalyst comprising CuNi 2 S 4 and ZnCdS was synthesized through one-step hydrothermal process. This bulk-phase heterojunction increases the nano-contact areas while maintaining an interface distance that is smaller than the diffusion distance of the carriers. Consequently, the optimal hydrogen production rate achieved was 33.87 mmol/g h, which is an order of magnitude greater than that of pure ZnCdS at 3.35 mmol/g h. Furthermore, the quantum efficiency at 400 nm reached 16 %. The photocurrent of the ZCS-CNS-3 % sample was 57.1 μA/cm², 4.35-fold of pure ZnCdS at 13.1 μA/cm². The incorporation of CuNi 2 S 4 significantly reduces the overpotential required for hydrogen evolution, while concurrently reducing the carrier transfer resistance by an order of magnitude. This bulk-phase structure not only broadens the prospects for the advancement of green and clean energy solutions but also enhances the methodologies for synthesizing nano-contact photocatalysts.