Ultra-thin carbon doped TiO2 nanotube arrays for enhanced visible-light photoelectrochemical water splitting

[Display omitted] •A simple route to fabricate the ultra-thin carbon-doped TiO2 nanotube arrays (TNTAs).•UTC-doped TiO2@TNT exhibited enhanced visible light-assisted PEC water-splitting activity.•The mechanism of the enhanced H2 production performance has been discussed. TiO2 has been widely employed as a photocatalyst for water splitting owing to its high activity, low cost, abundance, safety, and stability. However, the further utilization of TiO2 is still confined to the wide band gap and the rapid recombination speed. Carbon has metallic conductivity and a large electron storage capacity, which can help to absorb photoexcited electrons and enhance charge separation and transfer. Herein, we fabricated the ultra-thin carbon-doped TiO2 nanotube arrays (TNTAs). The as-prepared UTC-doped TiO2@TNT exhibited high photoelectrochemical (PEC) activity, realizing a high H2 evolution rate up to 41.3 μmol cm-2 h−1 (AM 1.5G) and 1.3 μmol cm-2 h−1 (visible light), which exhibit significantly narrowed band gaps and decreased charge resistance. Using ultra-thin carbon doping in TiO2 nanotube arrays opens up a new avenue for optimizing photocatalysts for PEC water splitting.