A surface-alkalinized Ti3C2 MXene as an efficient cocatalyst for enhanced photocatalytic CO2 reduction over ZnO

Abstract

Photocatalytic reduction of carbon dioxide (CO₂) into hydrocarbon fuels has attracted increasing research attention in recent years. However, the fast recombination of photoinduced charge carriers and poor adsorption/activation capability of CO₂ molecules limit the photoconversion efficiency. Herein, we report on loading a two-dimensional (2D) titanium carbide (Ti₃C₂) MXene as a noble-metal-free cocatalyst onto zinc oxide (ZnO) via a facile electrostatic self-assembly method for efficient CO₂ photoreduction. It is interesting to find that the ZnO loaded with 7.5 wt% of surface-alkalinized Ti₃C₂ exhibited remarkably improved evolution rates of CO (30.30 μmol g⁻¹ h⁻¹) and CH₄ (20.33 μmol g⁻¹ h⁻¹), which were approximately 7-fold and 35-fold those of bare ZnO, respectively. The surface-alkalinized Ti₃C₂ MXene is believed to play a crucial role in improving the separation/transfer of photoinduced charge carriers and the adsorption/activation of CO₂ molecules, accounting for the superior photocatalytic activity of CO₂ reduction. Our work demonstrates that the Ti₃C₂ MXene could be employed as a noble-metal-free cocatalyst for efficient photocatalytic CO₂ reduction.