Construction of ternary hybrid layered reduced graphene oxide supported g-C3N4-TiO2 nanocomposite and its photocatalytic hydrogen production activity

Reduced graphene oxide (rGO) supported g-C3N4-TiO2 ternary hybrid layered photocatalyst was prepared via ultrasound assisted simple wet impregnation method with different mass ratios of g-C3N4 to TiO2. The synthesized composite was investigated by various characterization techniques, such as XRD, FTIR, Raman Spectra, FE-SEM, HR-TEM, UV-vis DRS Spectra, XPS Spectra and PL Spectra. The optical band gap of g-C3N4-TiO2/rGO nano composite was found to be red shifted to 2.56 eV from 2.70 eV for bare g-C3N4. It was found that g-C3N4 and TiO2 in a mass ratio of 70:30 in the g-C3N4-TiO2/rGO nanocomposite, exhibits the highest hydrogen production activity of 23,143 mu mol g(-1)h(-1) through photo catalytic water splitting. The observed hydrogen production rate from glycerol-water mixture using g-C3N4-TiO2/rGO was found to be 78 and 2.5 times higher than g-C3N4 (296 mu mol g(-1)h(-1) and TiO2 (11,954 mu mol g(-1)h(-1)), respectively. A direct contact between TiO2 and rGO in the g-C3N4-TiO2/rGO nanocomposite produces an additional 10,500 mu mol g(-1)h(-1) of hydrogen in 4 h of photocatalytic reaction than the direct contact between g-C3N4 and rGO. The enhanced photocatalytic hydrogen production activity of the resultant nanocomposite can be ascribed to the increased visible light absorption and an effective separation of photogenerated electron-hole pairs at the interface of g-C3N4-TiO2/rGO nanocomposite. The effective separation and transportation of photogenerated charge carriers in the presence of rGO sheet was further confirmed by a significant quenching of photoluminescence intensity of the g-C3N4-TiO2/rGO nanocomposite. The photocatalytic hydrogen production rate reported in this work is significantly higher than the previously reported work on g-C3N4 and TiO2 based photocatalysts. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.