Enhanced photocatalytic hydrogen formation over Fe-loaded TiO2 and g-C3N4 composites from mixed glycerol and water by solar irradiation

Fe-doped TiO2 with various levels of Fe (0.5, 1, 2, 3, and 5 wt. %) was made via impregnation, and the Fe-doped TiO2 catalysts were modified with g-C3N4. These materials were studied using FE-SEM, Uv-DRS, TEM, Raman, FT-IR, and XPS techniques. The results show that the fine dispersed Fe3+ and g-C3N4 expanded the photoresponse of titania into the visible region on the introduction of ferric ions and fine dispersion of g-C3N4 on TiO2. The hydrogen formation rate from solar light-induced photocatalysis can be greatly increased by coupling g-C3N4 with the above Fe-doped TiO2, and the 1 wt. % Fe-modified TiO2 with the g-C3N4 composite has high photoactivity and shows excellent photostability for hydrogen production by solar irradiation. The stable hydrogen evolution of 1 wt. % Fe-doped TiO2 with g-C3N4 is some 17 times higher than that found with unmodified TiO2. The results show that the photogenerated electrons of g-C3N4 can directionally migrate to Fe-doped TiO2 due to intimate interfacial contacts and synergism operating between Fe-doped TiO2 and g-C3N4 where photogenerated electrons and holes are efficiently spatially separated. This separation retards the charge recombination rate and improves photoactivity.