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

Abstract

Rhodium-doped-TiO2 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.%. TiO2 nanostructures, nanocrystals (TSG) and nanotubes (NTSG) of TiO2, supporting Rh were characterized by X-ray diffraction, HR-TEM microscopy, N2 physisorption, H2-TPR, UV–vis, Raman spectroscopy and XPS.Likewise, the Rh/TSG and Rh/NTSG nanostructures, evaluated in the H2 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 TiO2-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 TiO2 species improved remarkably the H2 production.