Copper-Doped ZnS with Internal Phase Junctions for Highly Selective CO Production from CO₂ Photoreduction

ZnS is one of the promising earth-abundant catalysts for photoreduction reactions. The performance of ZnS in CO2 reduction is, however, limited because of its wide band gap, fast recombination of charge carriers, as well as low product selectivity due to the competing hydrogen evolution reaction (HER). Herein, Cu-doped ZnS containing abundant sphalerite and wurtzite phase (S–W) junctions is prepared and an enhanced photocatalytic activity with high selectivity in CO production is demonstrated. Both experimental and theoretical results reveal that Cu incorporation and the S–W phase junction enhance light absorption and promote photocatalytic activity. The presence of a Cu ion contributes to the CO generation and suppresses the competing HER by enhancing the bonding of the catalyst surface with •CO adsorbates. This work provides useful insights into the modification of CO2 reduction photocatalysts to realize high catalytic efficiency and product selectivity.