Selective visible-light driven highly efficient photocatalytic reduction of CO2 to C2H5OH by two-dimensional Cu2S monolayers

Abstract

Solar-driven highly-efficient photocatalytic reduction of CO₂ into value-added fuels has been regarded as a promising strategy to assuage the current global warming and energy crisis, but developing highly product-selective, long-term stable and low-cost photocatalysts for C₂ production remains a grand challenge. Herein, we demonstrate that two-dimensional β- and δ-phase Cu₂S monolayers are promising photocatalysts for the reduction of CO₂ into C₂H₅OH. The calculated potential-limiting steps for the CO₂ reduction reaction (CO₂RR) are less than 0.50 eV, while those for the hydrogen evolution reaction are as high as 1.53 and 0.87 eV. Most strikingly, the C–C coupling only needs to overcome an ultra-low kinetic barrier of ∼0.30 eV, half of that on the Cu surface, indicating that they can boost the C₂H₅OH conversion efficiency greatly. Besides, these catalysts also exhibit satisfactory band edge positions and suitable visible light absorption, rendering them ideal for the visible light driven CO₂RR. Our work not only provides a promising photocatalyst for achieving the efficient and selective CO₂RR, but also brings new opportunities for advanced sustainable C₂H₅OH product.