Enhanced Surface and Bulk Recombination Kinetics by Virtue of Sequential Metal and Nonmetal Incorporation in Hematite-Based Photoanode for Superior Photoelectrochemical Water Oxidation

Harvesting clean energy from sunlight is a promising and desirable path to resolve the energy challenge through photoelectrochemical (PEC) water splitting. Herein, we report the design and synthesis of a stable hematite photoanode with sequential metal and nonmetal incorporation to resolve the limiting factors such as low carrier density and high charge recombination for its practical applications. Comprehensive morphological, optical, and photoelectrochemical properties of the doped hematite photoanodes are presented to understand the mechanisms by which the dopant incorporation impacts the photoelectrode performance. It is found that with controlled calcination temperature metal and nonmetal incorporation not only increases the carrier density but also facilitates faster charge transfer. The charge carrier density of the photoanode derived from Mott–Schottky plot shows an increase by an order of magnitude, i.e., from 5.1 × 1019 to 5.7 × 1020 cm–3, with dual modification. The dual modified hematite photoanode shows a photocurrent density of 2.56 mA/cm2 at 1.23 V vs RHE, which is ∼5-fold higher as compared to that of the bare hematite photoanode. We believe that the present method of designing and fabricating the hematite photoanode by sequential incorporation of metal and nonmetal will provide an economical and efficient strategy for better solar energy conversion.