Photocatalytic CO2 reduction to syngas using nickel phosphide loaded CdS under visible light irradiation

Photocatalytic CO2 reduction is a sustainable pathway to produce syngas (H2 + CO) which is a key feed stock for the production of many important liquid fuels on the industrial scale. However, achieving appropriate tunable ratio of H2:CO in syngas for commercial purpose is a challenging task. In this work, we present a low cost and non-noble metal, phosphide based co-catalyst - Ni2P loaded CdS photocatalyst system for the photocatalytic CO2 reduction. Ni2P as a co-catalyst fosters efficient charge separation of photoexcited charges generated in CdS producing syngas. 3 wt.% CdS/Ni2P exhibited exceptional performance of 50.6 µmol/g/h of CO evolution rate and 115 µmol/g/h of H2 evolution rate with a syngas composition varying from 2 to 4 in H2:CO ratio. Further, the first-principles density functional theory (DFT) calculations were performed to study surface energetics of the catalyst system and the results are found to be consistent with our experimental findings. Indeed, they establish that the composite favors the CO2 photoreduction into syngas more efficiently as compared to pure surfaces.