Synthesis and characterization of black hydrogenated TiO2-rGO nanocomposites with enhanced photocatalytic activity

Abstract

In this research, TiO2-GO composites were prepared by combination process included sol-gel for synthesizing TiO2 nanoparticles and afterward loaded GO on TiO2 (NPs) with hydrothermal treatment in ethanol/water medium. The black TiO2–H nanoparticles and TiO2-rGO-H nanocomposites were prepared through simple thermal hydrogen treatment at 600 °C for 3 h. The synthesized nanoparticles and the composite catalysts were characterized by XRD, FESEM, FTIR analyzes and the BET (Brunauer–Emmett–Teller) surface area measurement. The results revealed that synthesized TiO2 nanopowder was almost anatase phase with high crystallinity when coupled with GO leads to a decrease in the size of the crystallites by creation of smaller TiO2 clusters in result of enhanced dispersion of TiO2 on GO sheets. However, adding up GO has slightly improved optical properties of the photocatalyst samples. Compared with TiO2-GO composites, the high temperature (600 °C) hydrogenation produced anatase/rutile black TiO2-rGO nanocomposites enhanced hydrogen production rate 9 orders of magnitude higher than those observed for TiO2 powders, reached values of more than 368 μ mol g− 1 h – 1. A significant reduction in the energy band gap of 2.72 eV (DRS results) and also decreasing the electron-hole recombination according to PL spectra results has been recorded for TiO2-rGO-H nanocomposite. In addition, the black TiO2 nanoparticles and TiO2-rGO nanocomposites possessed much more concentration of oxygen vacancies and carrier concentration according to Raman analysis.