Intrinsically Ru-Doped Suboxide TiO2Nanotubes for Enhanced Photoelectrocatalytic H2Generation

Abstract

In the present research, we investigate the synergistic effects of Ru-doping and Ar/H2 reduction treatment on the photoelectrochemical water splitting performance and hydrogen evolution rate of TiO2 nanotube array photoelectrodes. The Ti-Ru alloy with 0.2 at. % Ru was used to grow anodic self-organized Ru-doped TiO2 nanotube layers. An ideal synergy between Ar/H2 reduction treatment and Ru-doping results in the extended absorption toward the visible light region and improved photoelectrocatalytic activity. The black Ru-doped TiO2-x photoanode's water splitting rate improves remarkably (∼ninefold) compared to the black TiO2-x sample (∼twofold). Moreover, the black Ru-doped TiO2-x photoanode shows a considerable increase in the H2 production rate (1.91 μmol h-1 cm-2) compared with the pristine TiO2 nanotube layer (0.044 μmol h-1 cm-2). We have also developed an ab initio model of pristine, Ru-doped, and Ru-doped hydrogenated TiO2 nanotubes to rationalize our experimental findings from the theoretical perspective.