MoOx layer with abundant oxygen vacancies modified on Sn-doped α-Fe2O3 film for enhanced photoelectrochemical water oxidation performance.

The photoelectrochemical (PEC) water oxidation performance of α-Fe₂O₃ photoanode can be improved by constructing proper heterojunction to promote photo-induced carrier separation and interfacial charge transfer. Here, an optimized MoO_x layer with abundant oxygen vacancies was modified on Sn doped α-Fe₂O₃ film by simple spin coating and thermal reduction method to form a heterojunction with enhanced PEC performance. XPS results suggest that increased oxygen vacancy concentration in MoO_x layers can be achieved by post annealing the samples in N₂. PEC tests of the prepared photoanodes revealed that the optimal N₂-annealed MoO_x/Sn-Fe₂O₃ photoanode with abundant oxygen vacancies possesses the best photocurrent density (1.88 mA/cm² at 1.23 V vs RHE), which is up to 1.84 and 8.17 times compared with Sn-Fe₂O₃ and pristine Fe₂O₃, respectively. The improved PEC performance can be attributed to the enhanced band bending and built-in electric field after increasing the oxygen vacancy concentration in MoO_x, which promoted the carrier separation and transfer. This work demonstrates that constructing heterojunction using a MoO_x layer with abundant oxygen vacancies is an effective approach to enhance the PEC performance of α-Fe₂O₃ photoanode. [ABSTRACT FROM AUTHOR]