Construction of an Electron Capture and Transfer Center for Highly Efficient and Selective Solar-Light-Driven CO₂ Conversion.

Abstract

Exploring high-efficiency photocatalysts for selective CO₂ reduction is still challenging because of the limited charge separation and surface reactions. In this study, a noble-metal-free metallic VSe₂ nanosheet was incorporated on g-C₃N₄ to serve as an electron capture and transfer center, activating surface active sites for highly efficient and selective CO₂ photoreduction. <i>Quasi in situ</i> X-ray photoelectron spectroscopy (XPS), soft X-ray absorption spectroscopy (sXAS), and femtosecond transient absorption spectroscopy (fs-TAS) unveiled that VSe₂ could capture electrons, which are further transferred to the surface for activating active sites. <i>In situ</i> diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations revealed a kinetically feasible process for the formation of a key intermediate and confirmed the favorable production of CO on the VSe₂/PCN (protonated C₃N₄) photocatalyst. As an outcome, the optimized VSe₂/PCN composite achieved 97% selectivity for solar-light-driven CO₂ conversion to CO with a high rate of 16.3 μmol·g^-1·h^-1, without any sacrificial reagent or photosensitizer. This work offers new insights into the photocatalyst design toward highly efficient and selective CO₂ conversion.