Inter-plane 2D/2D ultrathin La2Ti2O7/Ti3C2 MXene Schottky heterojunctions toward high-efficiency photocatalytic CO2 reduction

Ascribing to incremental fossil fuels emissions, the utilization and conversion of CO2 and development of renewable energy is globally essential and significative. Ultrathin 2D/2D heterojunctions with fast photo-generated electrons transmission channels illustrate a better strategy to improve photocatalytic activity. Herein, combing La2Ti2O7 with metallic few-layered Ti3C2 MXene to construct inter-plane 2D/2D heterojunction was in situ self-assembled through solvothermal method. Benefiting from the advantages including stability, conductivity, abundant active sites and formation of Schottky junctions, as expected, the ultrathin 2D/2D La2Ti2O7/Ti3C2 MXene nanosheets presented much improved photocatalytic ability for CO2 reduction to CO and CH4, which is about 4.6 and 11.4 times higher than that of mechanical mixed La2Ti2O7 and Ti3C2 MXene. fs-TAS and XPS provided direct evidence that the prominence of La2Ti2O7/Ti3C2 MXene in photocatalytic CO2 reduction reaction over other opponents should be attributed to the synergetic effect of efficient charge carrier mobility and formed 2D/2D Schottky heterojunction interfacial contact between La2Ti2O7 and Ti3C2 MXene. Intermediates revealed by in-situ DRIFTS and corresponding atomic-level DFT calculations confirmed the mechanism, pathways and selectivity for photocatalytic CO2 conversion. This work expanded promising prospects arouses new impetus for deepening the prehension of the mechanism of photocatalytic CO2 reduction, designing and fabrication of Schottky heterojunctions for application in conversion and utilization of CO2.