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.