Photocatalytic CO₂ reduction of Ag/Ag₂S/Ti₃C₂T_<i>X</i> heterojunctions with enhanced interfacial charge transfer

Photocatalytic reduction of CO₂ to produce organic fuels is a promising strategy for addressing carbon reduction and energy scarcity. Transition metal carbides (Ti₃C₂T _<i>X</i> ) are of particular interest due to their unique layered structures and excellent electrical conductivity. However, the practical application of Ti₃C₂T _<i>X</i> is limited by the poor separation efficiency of photogenerated charge carriers and the low migration ability of photogenerated electrons. Herein, Ag/Ag₂S/Ti₃C₂T _<i>X</i> heterojunctions were synthesized by depositing Ag/Ag₂S nanoparticles onto layered Ti₃C₂T _<i>X</i> substrates using a combination of co-precipitation and photoreduction methods. Fluorescence spectra, UV diffuse reflection, and photoelectric chemical characterizations demonstrated that Ag/Ag₂S/Ti₃C₂T _<i>X</i> heterojunctions provided effective channels for the reverse and synergistic migration of electrons and holes, leading to improved spatial separation. Notably, the Ag component in the composite acts as an electron acceptor and reactive center, significantly enhancing the migration ability of photogenerated electrons. The total alcohol yield over Ag/Ag₂S/Ti₃C₂T _<i>X</i> (125.3 μmol g_catal. ^-1) was 5.1 times higher than that on Ag₂S (24.7 μmol g_catal. ^-1) and 2.1 times higher than on Ti₃C₂T _<i>X</i> (60.7 μmol g_catal. ^-1). This study offers valuable insights into designing efficient photocatalytic CO₂ reduction catalysts.