Boosting the Photocatalytic Activity of P25 for Carbon Dioxide Reduction by using a Surface‐Alkalinized Titanium Carbide MXene as Cocatalyst

Abstract Although they are widely used as cocatalysts in promoting photocatalysis, practical application of noble metals is limited by their high cost and rarity. Development of noble‐metal‐free cocatalysts is thus highly demanded. Herein titanium carbide (Ti 3 C 2 ) MXene is shown to be a highly efficient noble‐metal‐free cocatalyst with commercial titania (P25) for photocatalytic CO 2 reduction. Surface alkalinization of Ti 3 C 2 dramatically enhances the activity; the evolution rates of CO (11.74 μmol g −1 h −1 ) and CH 4 (16.61 μmol g −1 h −1 ) are 3‐ and 277‐times higher than those of bare P25, respectively. The significantly enhanced activity is attributed to the superior electrical conductivity and charge‐carrier separation ability, as well as the abundant CO 2 adsorption and activation sites of surface‐alkalinized Ti 3 C 2 MXene, indicating its promise as a highly‐active noble‐metal‐free cocatalysts for photocatalytic CO 2 reduction.