Novel TiO2@[TiO6]/CoTi layered double hydroxide as a superior ultraviolet/infrared heterojunction for enhanced infrared-prompted water splitting to hydrogen

Abstract

Recently, photocatalytic water splitting to hydrogen is the perfect process to substitute petroleum consumption by the clean production and burning cycles of hydrogen. However, this process is still far from the global application because photocatalysts' work out of infrared (IR)-region (53% of sunlight). Herein, TiO2 is successfully modified for IR-induced H2-generation by two pathways; 1) Adjusting the (Co)-doping in [TiO6]/CoTi layered double hydroxide (TCT-LDH) at a ratio of 2.65 for suitable IR-responsivity (1.6 eV); 2) Fabrication of UV/IR heterojunction through nanocasting of the novel (TiO2 @TCT-LDH)-semiconductor. The TCT-LDH and TiO2 @TCT-LDH are prepared by modified precipitation of (TiCl4)-vapors over urea-hydrolysis. Under IR-irradiation, TCT-LDH reaches 139 μmolg-1h-1 hydrogen evolution rate (HER) without scavengers. While the TiO2 @TCT-LDH heterojunction reaches 2158 μmolg-1h-1 without Pt-loading, which is among the highest reported values. The heterojunction offers a superior charge separation and mobility by the synergy between [TiO6]-sites and LDH-structure. The newly synthesized TiO2 @TCT-LDH can display a potential strategy for clean and continuous hydrogen generation.