Facet-selective synthesis of cadmium sulfide photocatalysts for high-efficiency CO2 conversion

The surface of photocatalysts plays a key role in the adsorption and activation of CO 2 molecules. Establishing the conformational relationship between the crystalline phase of the photocatalysts and the CO 2 reduction reaction (CO 2 RR) activity is crucial to understanding the catalytic reaction mechanism. Herein, we synthesized CdS catalysts with different exposed crystalline facets (CdS[100], CdS[001], and CdS[111]) using hydrothermal and water bath methods and evaluated their photocatalytic CO 2 RR performances. The results showed that CdS[001] displayed an optimal activity with a 203.2 μmol g −1  h −1 of CO generation rate compared with CdS[100] and CdS[111]. More importantly, the CdS[001] catalyst shows the best CO selectivity ( S CO : ~ 86.6 %) and CO 2 reduction selectivity ( S CO2 : ~95.4 %) compared with CdS[100] ( S CO : 79.3 %; S CO2 : 90.0 %) and CdS[111] ( S CO : 79.6 %; S CO2 : 82.8 %). The optimal CdS[001] catalyst significantly inhibited the competing hydrogen evolution reaction. The adsorption and activation behaviors of CO 2 on various exposed surfaces of CdS are explored in depth based on density functional theory calculations and in-situ Fourier transform infrared spectra measurements. This work provides new insights into understanding the role of facet control in enhancing photocatalytic CO 2 conversion.