Environmentally Sustainable Synthesis of a CoFeO-TiO/rGO Ternary Photocatalyst: A Highly Efficient and Stable Photocatalyst for High Production of Hydrogen (Solar Fuel).

Herein, a magnetically separable reduced graphene oxide (rGO)-supported CoFeO-TiO photocatalyst was developed by a simple ultrasound-assisted wet impregnation method for efficient photocatalytic H production. Integration of CoFeO with TiO induced the formation of Ti sites that remarkably reduced the optical band gap of TiO to 2.80 eV from 3.20 eV. Moreover, the addition of rGO improved the charge carrier separation by forming Ti-C bonds. Importantly, the CoFeO-TiO/rGO photocatalyst demonstrated significantly enhanced photocatalytic H production compared to that from its individual counterparts such as TiO and CoFeO-TiO, respectably. A maximum H production rate of 76 559 μmol g h was achieved with a 20 wt % CoFeO- and 1 wt % rGO-loaded TiO photocatalyst, which was approximately 14-fold enhancement when compared with the bare TiO. An apparent quantum yield of 12.97% at 400 nm was observed for the CoFeO-TiO/rGO photocatalyst under optimized reaction conditions. This remarkable enhancement can be attributed to synergistically improved charge carrier separation through Ti sites and rGO support, viz., Ti-C bonds. The recyclability of the photocatalyst was ascertained over four consecutive cycles, indicating the stability of the photocatalyst. In addition, it is worth mentioning that the photocatalyst could be easily separated after the reaction using a simple magnet. Thus, we believe that this study may open a new way to prepare low-cost, noble-metal-free magnetic materials with TiO for sustainable photocatalytic H production.