Bifunctional Role of Zn in α-Fe 2 O 3 Boosts the Photoelectrochemical Water Oxidation: Zn 2+ Doping and Catalytic Effect

The serious recombination of photocarriers in hematite (α-Fe2O3) is the intrinsic limitation that lessens the photoelectrochemical (PEC) performance of water splitting. For the first time, the n-type Zn doped α-Fe2O3 nanowire was successfully fabricated and used as the photoanode for PEC water splitting. The Zn doped α-Fe2O3 demonstrated enhanced PEC performance over the single α-Fe2O3, the photocurrent density increased up to 0.88 mA/cm2(1.23 VRHE), which showed a 44-fold increase than the α-Fe2O3 and accompanied by 300 mV negative shift of onset potential. The coupled electrochemical measurements and density functional theory calculations (DFT) revealed the bifunctional role of Zn doping: increasing the carrier density and accelerating oxygen evolution kinetics simultaneously, by which the charge separation efficiency improved significantly. This work provides a deep understanding of the role of Zn in the α-Fe2O3 photoanodes and the strategy could be extended to other photoactive systems.