Greatly enhanced CO2 electrocatalytic reduction performance of Ag2Se nanocatalyst via phase-engineering

Abstract

Crystal phase of semiconductor nanocatalysts has a great influence on their catalytic performance. Ag-based nanomaterials are fascinating electrocatalysts for CO2 reduction reaction (CO2RR) toward CO formation. However, the phase-dependent catalytic behavior of Ag-based electrocatalysts has not been studied so far. Herein, we report a crystal phase-dependent catalytic behavior of Ag2Se nanoparticles based on the successful synthesis of monoclinic (m-Ag2Se) and orthorhombic (o-Ag2Se). Remarkably, m-Ag2Se nanoparticles deliver an enhanced CO Faradic efficiency up to 98.1 % at −0.90 V vs. RHE as well as the long-term stability under an extremely high current density, far exceeding that of o-Ag2Se. Theoretical simulations reveal that m-Ag2Se surface not only facilitates the adsorption and stabilization of *COOH species, but also tends to inhibit HER, thus accounting for the high activity and selectivity for CO formation during CO2RR. This work offers new insights into the facile design of electrocatalysts in catalysis via crystal phase structure regulation.