Preparation of TiO2-Based Photocatalysts Synergistically Modified with Fe3+–Graphene and Their Visible-Light-Catalyzed Hydrogen Production from Ammonia Borane

Abstract

TiO2-based photocatalysts are promising materials that show great potential in the field of catalysis due to their excellent properties including nontoxicity, high photocatalytic performance, and outstanding thermal and chemical stability. However, several challenges exist regarding TiO2 applications for catalytic hydrogen production. In this work, Fe- and graphene-comodified TiO2 (Fe–rGO/TiO2) was synthesized via a two-step solvothermal method. In addition, the effect of Fe3+ and graphene addition upon the catalytic performance of TiO2 was investigated based on the ammonia borane hydrogen production reaction, and the catalysts were characterized by SEM, XRD, XPS, UV–vis, FT-IR, and Raman methods. Batch experiments showed that the synthesized Fe–rGO/TiO2 composites exhibited high photocatalytic performance for hydrogen production from ammonia borane under visible-light irradiation. Moreover, the highest photocatalytic hydrogen production rate (1235.32 μmol·min–1·gcat–1) of 2%Fe–1%rGO/TiO2 was observed under visible-light irradiation at 25 °C, and the photocatalytic activity of the sample remained almost unchanged after the fifth cycle. The XRD, XPS, FT-IR, and Raman analyses showed that Fe and graphene successfully modified TiO2 and the presence of Ti4+. In addition, the extended visible-light absorption range and a reduction of the band gap of Fe–rGO/TiO2 were demonstrated by UV–vis diffuse reflectance spectra and calculation of the band gap. Also, the preparation of hydrogen from the hydrolysis of ammonia borane photocatalyzed by TiO2 composites was discussed. These findings are crucial for designing TiO2-based photocatalysts with high performance for photocatalytic hydrogen production.