Decorating g-C₃N₄ with alkalinized Ti₃C₂ MXene for promoted photocatalytic CO₂ reduction performance

Photocatalytic reduction of carbon dioxide (CO₂) under visible light irradiation for producing high-value fuel has attracted tremendous attention in recent years. In this study, titanium carbide MXene (Ti₃C₂) was used as a noble metal-free co-catalyst by simply mixing graphitic carbon nitride (g-C₃N₄) and alkalized Ti₃C₂. The carbon monoxide evolution rate of the optimized composite (5%TCOH-CN) from photocatalytic reduction of CO₂ was 5.9 times higher than that of pure g-C₃N₄. Alkalized Ti₃C₂ was responsible for the superior photocatalytic activity due to its excellent electrical conductivity and large CO₂ adsorption capacity. Furthermore, the separation of the photo-induced electron-hole pairs was greatly enhanced because of the large Fermi level difference between alkalized Ti₃C₂ and pure g-C₃N₄. This work demonstrates the potential of MXenes as noble metal-free co-catalyst for photocatalysis processes such as carbon dioxide reduction reaction and nitrogen reduction reaction.