Photoelectrochemical water oxidation and methylene blue degradation enhanced by Nb doping and CoPi modification for hematite photoanodes

Nanostructured alpha-Fe2O3 films doped with niobium and supported with CoPi cocatalyst (Nb-alpha-Fe2O3 @CoPi) are prepared by hydrothermal growth together with electrochemical deposition. The effect of Nb doping and CoPi cocatalyst modification on the performance of photoelectrochemical water oxidation and me-thylene blue degradation of alpha-Fe2O3 is studied in detail. It shows that Nb doping and CoPi modification toward alpha-Fe2O3 not only enhances its light absorption, but also improves its electrical properties, including conductivity, bulk charge separation efficiency and charge transfer efficiency at the electrode/electrolyte interface. When used as photoanode for photoelectrochemical water oxidation, the Nb-alpha-Fe2O3 @CoPi photoanodes show a negative shift of 540 mV in the onset potential in comparison with the pristine alpha-Fe2O3 films. At the same time, the photocurrent density (at 1.6 V, vs. RHE) of Nb-alpha-Fe2O3@CoPi is more than three times that of the pristine alpha-Fe2O3, reaching 1.44 mA center dot cm-2. In addition, the obtained Nb-alpha-Fe2O3 @CoPi photoanodes also show excellent performance in visible light-driven photoelectrochemical degradation of methylene blue, a common pollutant in wastewater. For example, a degradation rate of 98% is achieved in 2 h by the Nb-alpha-Fe2O3 @CoPi, which is 3.6 times that of the pristine alpha-Fe2O3 (26%). (c) 2023 Elsevier B.V. All rights reserved.