Unveiling the potential of Cu‒Pd/CdS catalysts to supply and rectify electron transfer for H2 generation from water splitting†

Abstract

As foreseeable fuel, getting hydrogen from water can be the game changer promise for renewable energy sector. Reason is that it has potential to be used as alternative to the fossil fuels. Current project has been designed to develop catalysts that can produce hydrogen from water on sunlight. For the purpose, CdS, Cu/CdS, Pd/CdS, and Cu‒Pd/CdS catalysts have been successfully synthesised and utilized for hydrogen generation. Catalytic activity of pristine CdS has been potentially enhanced with Cu and Pd cocatalysts that were deposited via chemical reduction strategy. Morphology and optical characteristics have been assessed via XRD, Raman, UV-Vis/DRS, PL, SEM, HRTEM and AFM techniques. Phase purity, compositions and charge transfer have been confirmed by EDX, XPS and EIS studies. Using similar conditions, photoreactions and H2 evolution experiments were performed in quartz reactor (UK/Velp-Sci) and GC-TCD (Shimadzu, 2014) respectively. Overall, Cu‒Pd/CdS catalyst (0.2% Cu and 0.8% Pd) was found most active that has potentially delivered 33.71 mmolg‒1h‒1 of hydrogen. Higher efficiencies were attributed to the existence of Cu and Pd on CdS surfaces. It has been predicted that Cu cocatalysts increase the electron densities on CdS surfaces (i.e. active sites), while Pd cocatalysts reduce the back reactions (higher charge transportation) by forming Schottky junctions. Various factors like pH, temperature, intensity of light and catalyst dose have been evaluated and discussed. Based on the results and activities, it has been concluded that ascribed approach hold potential to replace the fossil fuels.