Plasma-chemical reduction of iron oxide photoanodes for efficient solar hydrogen production

摘要

We demonstrate the effect of hydrogen plasma treatment on hematite films as a simple and effective strategy for modifying the existing substrate to improve significantly the band edge positions and photoelectrochemical (PEC) performance. Plasma treated hematite films were consist of mixed phases (Fe_3O_4:α-Fe_2O_3) which was confirmed by XPS and Raman analysis, treated films also showed higher absorption cross-section and were found to be a promising photoelectrode material. The treated samples showed enhance photo-current densities with maximum of 3.5 mA/cm~2 at 1.8 V/RHE and the photocurrent onset potentials were shifted from 1.68 V_(RHE)(untreated) to 1.28 V_(RHE) (treated). Hydrogen plasma treatment under non-equilibrium conditions induced a valence dynamics among Fe centers in the sub-surface region that was sustained by the incorporation of hydrogen in the hematite lattice as supported by the density functional theory calculations.