Enhanced selectivity and charge transfer over highly dispersed Cd0.2Zn0.8S/meta-kaolinite catalysts for CO2 photoreduction

Abstract

In this work, a novel hybrid photocatalyst consisting of Cd0.2Zn0.8S grown on a defect-rich meta-kaolinite nanosheet (CZS/MK) composite was investigated for the photoreduction of CO2 to CO in the presence of simulated sunlight with high selectivity. CZS/MK displayed a CO yield of 21.3 µmol g−1h−1 with a remarkable selectivity of 97.4 % without any co-catalyst and sacrificial reagent. The addition of MK to the catalyst altered CZS hydrophilicity and improved CO selectivity. Moreover, kaolinite is relatively inexpensive, and the defects in MK can optimize pore size distribution and structure of Cd0.2Zn0.8S, resulting in improved dispersion and a higher quantity of exposed active sites on the composite material. Experimental investigations combined with DFT calculations illustrated that the adsorption configuration involving the introduction of kaolinite was more favorable for CO2 activation, which ultimately decreased the formation barrier of key intermediate *COOH. In situ Fourier transform-infrared analysis indicated that Cd0.2Zn0.8S/MK tended to produce vital *COOH intermediates, thereby achieving higher CO conversion efficiency. This study provides novel insights into the utilization of kaolinite-based catalysts for enhancing CO2 photoreduction.