Tailored TiO2 nanostructures for supporting Rh3O2 and Rh0 nanoparticles: Enhanced photocatalytic H2 production

Abstract Rhodium-doped-TiO 2 nanostructures synthesized by the sol–gel and hydrothermal methods were obtained and tested for the photocatalytic production of hydrogen. The rhodium loadings were 0.1, 0.3, and 0.5 wt.%. TiO 2 nanostructures, nanocrystals (TSG) and nanotubes (NTSG) of TiO 2 , supporting Rh were characterized by X-ray diffraction, HR-TEM microscopy, N 2 physisorption, H 2 -TPR, UV–vis, Raman spectroscopy and XPS. Likewise, the Rh/TSG and Rh/NTSG nanostructures, evaluated in the H 2 production showed remarkable activity (7246 μmol h −1  g −1 for 0.5Rh/TSG nanocrystals and 4856 μmol h −1  g −1 for 0.5Rh/NTSG nanotubes) in comparison with the TSG and TiO 2 -NT supports without metal load (1358 μmol h −1  g −1 ) and the corresponding photolysis (50 μmol h −1 ). The photocatalytic improvement obtained with the Rh/TSG and Rh/NTSG nanostructures was supported by the combination of charge separators represented by Rh +3 species that can act as electron/hole traps, respectively. The synergistic effect between the Rh +3 species and electrons transferred from ethanol to different nanostructured TiO 2 species improved remarkably the H 2 production.