A promising one-step carbothermal reduction nitridation strategy for enhancing photoelectrochemical performance of TiO2 nanowire array-based catalysts with stable nitrogen doping and desired core-double shell structure

Abstract

Non-metallic nitrogen doping and carbon coating may be considered as the most promising strategies to improve the performance of the TiO2 photoelectrocatalyst by reducing the carrier recombinant rate, enhancing stability, and broadening light corresponding spectrum. In this study, a one-stage carbothermal reduction nitridation (CRN) strategy is proposed to improve the photoelectrocatalytic performance (PEC) of the TiO2 nanowires for hydrogen production. TiO2 nanowires derived nitrogen-doped TiO2/Ti(C0.7N0.3) co-catalyst/nitrogen-doped carbon (N-TiO2/Ti(CN)/N-C) core-double shell nanowire arrays (NWAs) on the Ti substrate have been successfully developed with 2D g-C3N4 addition as nitrogen and carbon source. The unique N-TiO2/Ti(CN)/N-C composite structure offers superior PEC performance over the original TiO2 NWAs when exposed to both simulated sunlight and visible light conditions. The photocurrent density of N-TiO2/Ti(CN)/N-C can increase by approximately 20.5-fold and 18.4-fold when subjected to simulated sunlight and simulated visible light, respectively, compared to the pure TiO2 NWAs. The remarkable activity of the catalysis under visible light can be ascribed to the widened absorption spectrum that emanates from nitrogen doping, along with the reinforced conductivity that results from the dual-shell structure that promotes the separation and transfer of carriers that are generated by light.