Van der Waals heterojunction for selective visible-light-driven photocatalytic CO2 reduction

Abstract

The product selectivity and efficiency of photocatalytic CO2 reduction are often restricted by the multi-electron transfer and reactive centers in the artificial photosynthetic system. To overcome these limitations, in this work, atomically thin carbon nitride (CN) coupled Bi9O7.5S6 (BOS) nanoplates were fabricated as a two-dimensional/two-dimensional (2D/2D) Van der Waals (VDW) heterojunction for CO2 photoreduction. Our experimental and density functional theory (DFT) calculations showed that the CO* could be adsorbed more strongly on BOS than CN, which could be further hydrogenated before desorption, explaining the observation why the main products of photocatalytic CO2 reduction on BOS was CH4 and CH3OH. Benefiting from the 2D/2D VDW heterojunction, 20CN/BOS revealed a CO generation rate of 37.2 μmol gcatalyst−1 under visible light irradiation, roughly 14.9-fold and 1.4-fold higher than that of BOS and CN alone. Our work paves a way to design new VDW hetero-structured photocatalysts for CO2 reduction to valuable products.