Unveiling the potential of Au cocatalysts to induce SPR charges on CuO/CdS system for sunlight driven hydrogen production†

Abstract

Atmospheric pollution and increasing costs of the fossil fuels have compelled researchers to explore the alternative sources. Objective of current project is to discover catalysts that can drive water splitting reaction with sunlight. To the purpose, visible light active catalysts i.e., CdS, CuO/CdS, and Au@CuO/CdS have been synthesized and evaluated for hydrogen generation activities. Gold cocatalysts have been employed to enhance the surface stability and catalytic efficiencies. Whereas, CuO/CdS heterojunction have been synthesized to improve charge separation ability. The optical characteristics, structural properties, and morphology of catalysts have been evaluated by UV–Vis/DRS, XRD, Raman, BET, SEM, AFM, PL and FTIR techniques. Chemical compositions, photocurrent or charge transfer have been verified with XPS, EDX and EIS results. Catalytic reactions were performed in photoreactor (150 mL/Pyrex), whereas hydrogen production activities were predicted via online GC-TCD (Shimadzu-2010/Japan). Results depict that catalyst with 0.8 % of Au on CuO/CdS exhibit relatively higher activity (i.e., 32.13 mmol g⁻¹ h⁻¹) than the other catalysts of the series. Higher activities were attributed to the presence of Au cocatalysts. It has been predicted that existence of gold develops Schottky junctions that progressively rectify the surface charges (i.e., movement of electrons). Additionally, gold induces the SPR charges and enhances activity of electrons. Schottky junctions formed by Au cocatalysts on CuO/CdS system restrict the charge recombination i.e., back reactions. In this study, various factors like temperature, pH, light intensity and dose of catalysts have been assessed and discussed. On the basis of activities, it has been concluded that work reported herein hold promise to replace the conventional catalysts used for hydrogen energy technologies.