Platinum quantum dots-decorated MXene-derived titanium dioxide nanowire/Ti3C2 heterostructure for use in solar-driven gas-phase carbon dioxide reduction to yield value-added fuels

Solar-driven photocatalytic CO2 reduction to produce valuable chemicals and fuels offers an attractive strategy in alleviating the energy crisis. Pt quantum dots (PtQDs) with TiO2 nanowire (TiO2NW)/Ti3C2 MXene heterostructures (Pt-TiO2NW/Ti3C2) with tight interfacial contacts between the various components were prepared at room temperature via oxidation reactions. The incorporated PtQDs played crucial roles as electron conduction bridges supported by the cocatalyst effect, effectively enhancing the separation efficiencies of photoinduced electron/hole pairs and improving CO2 reduction under simulated solar light irradiation. The Pt-TiO2NW/Ti3C2 heterostructures exhibited remarkable carbon monoxide (CO) and methane (CH4) production at respective rates of 38.14 and 36.15 μmol g−1 after 10 h of simulated solar light irradiation, an apparent quantum yield of 1.68%, and 79.2% selectivity for CH4. The photocatalytic activities of the Pt-TiO2NW/Ti3C2 heterostructures for CO2 reduction were significantly enhanced compared to those of TiO2NW/Ti3C2 and the single-component photocatalysts, and they exhibited remarkable stabilities even after five cycles. In addition, the densities of states and electronic characteristics of Ti3C2 MXene and Pt-TiO2NW/Ti3C2 were studied using density functional theory, and a synergistic mechanism of the improvement in CO2 photoreduction is proposed.