Insight into the Fabrication and Characterization of Novel Heterojunctions of Fe2O3and V2O5with TiO2and Graphene Oxide for Enhanced Photocatalytic Hydrogen Evolution: A Comparison Study

Affordable and highly efficient photocatalysts for the hydrogen evolution reaction (HER) are desirable to replace expensive bulk noble-metal use. Currently, many renewable energy studies are ongoing, focusing on photocatalytic water splitting to generate hydrogen. Transition-metal oxide-embedded TiO2photocatalysts have emerged as superior catalysts for the HER. Herein, we synthesize two different ternary composites consisting of TiO2-based transition-metal mixed oxides embedded onto graphene oxide (GO) layers which provide superior photocatalytic activity and stability during the HER over conventional expensive catalysts. The Fe2O3–TiO2and V2O5–TiO2particles were well anchored onto GO sheets, which prevents the agglomeration and allows one to explore maximum surface active sites. The synergistic interaction within the composite via heterojunction formation and the enhanced photophysical nature of the composite were well characterized. The optimized composites of GO-embedded Fe−Ti mixed oxide composite (g-FTMO) and V−Ti mixed oxide composite (g-VTMO) having metal−metal molar ratio of 2:1 with a 3.5 % (w/v) catalyst loading exhibit HER rates of 398.18 and 373.01 μmol h–1under solar radiation. The enhanced photocatalytic activity of optimized g-TMMO2:1was attributed to (i) the increased surface area by the incorporation of GO and (ii) the fact that the surface active sites with heterojunctions have lower e––h+pair recombination and faster electron transfer rates. The results reveal that the prepared composites can be treated as effective photocatalysts during the HER, and the conclusions pave the way for exploration of new similar catalysts for other applications.