Ultrathin TiO2 flakes optimizing solar light driven CO2 reduction

Photoreduction of CO2 into fuels over TiO2 helps to relieve the increasing energy crisis and the worsening global climate, while the low energetic efficiency impedes its large-scale applications. Herein, ultrathin TiO2 flakes are first put forward to fully optimize their crucial CO2 photoreduction processes through affording abundant catalytically active sites and increased two-dimensional conductivity. 1.66 nm thick TiO2 flakes are successfully fabricated by virtue of lamellar Tio(2) octylamine hybrid. The atomic thickness endows TiO2 with ultrahigh fraction of surface atoms, which ensures stronger UV light absorption compared with its bulk counterpart. Benefiting from the increased density of states near Fermi level and the vast majority of charge density concentrating on the surface, the ultrathin TiO2 flakes show increased conductivity confirmed by the temperature-dependent resistivities. The 3 times higher fluorescence lifetime, revealed by the time-resolved fluorescence spectroscopy, accounts for the increased separate rate of photoexcited electron-hole pairs. As an outcome, the ultrathin TiO2 flakes achieve a formate formation rate of 1.9 ttmol g(-1) h(-1), 450 times higher than that of bulk counterpart and also roughly 2 times higher than that of previously reported Ag-modified BaLa4Ti4O15. Briefly, our study will unlock many opportunities for designing efficient CO2 photoreduction performance. (c) 2016 Elsevier Ltd. All rights reserved.