In-situ Decoration of Unsaturated Cu Sites on Cu2O Photocathode for Boosting Nitrogen Reduction Reaction

Abstract Photoelectrochemical N2 reduction reaction (PEC NRR) into chemical energy source is a promising technique for solving environmental challenges and the energy crisis, which depends on the exploration of p-type photocathodes. Cu2O is a p-type semiconductor, which can be applied as a photocathode for PEC NRR. However, the adsorption and activation ability of N2 over the pristine Cu2O is still not ideal, causing the overall efficiency far below the theoretical value. In this work, we first proposed a feasible strategy to in-situ modify the surface of Cu2O with Cu-MOF, and the Cu-MOF/Cu2O heterostructure exhibited the significantly boosted NH3 production rate (7.16 mmol/m2/h). The ultra-thin Cu-MOF film takes a nature of porous structure and unsaturated Cu sites, contributing to a favorable interface environment for the adsorption and activation of N2. The N2 temperature programmed desorption and contrast photocurrent curves revealed the desirable selectivity for PEC NRR, and the isotope NMR further confirmed the accuracy of NH3 evolution process. Therefore, the organic–inorganic hybrid systems built from Cu-MOF and Cu2O would offer a new insight for establishing the efficient PEC NRR system.