Fermi level pinning strategy to boost the photocatalytic water splitting reaction of g-C3N4 with one-step multi-phase Fe2O3 self-assembly

In order to boost the photocatalytic water splitting activity of g-C3N4, depositions of various multiple cocatalyst combinations have been suggested in a number of previous studies. Despite the improvement in photocatalytic activities bestowed on g-C3N4 layers by the junctions of multiple cocatalyst particles at once, the complexities of synthesis procedures and fabrication conditions retard the wider applications or commercialization of such materials. In this study, we introduce a new effective strategy to improve the activity of a g-C3N4 photocatalyst in water splitting: dual function hole carrier transport enhancement and reduced surface reaction energy barrier with phase-control of Fe2O3. The self-assembled solvothermal composites of Fe2O3 and g-C3N4 resulted in the formation of a three-phase heterojunction. The best composite demonstrated an effective hydrogen production rate of 5.53 mmol g−1h−1. The formation of the three-phase heterojunction between the two components was shown to alter the chemical environment and a band diagram of the system is proposed. Our density functional theory (DFT) calculations and ultraviolet photoemission spectroscopy (UPS) measurements revealed that the combination of ε-Fe2O3 and α-Fe2O3 improves the photocatalytic activity of g-C3N4 by Fermi level pinning.