Interface Engineering of Hematite By Dual for Sunlight Driven Water Oxidation Activity

Abstract

The efficiency of nanostructures for solar-to-hydrogen production via carbon-free technology such as photoelectrochemical water-splitting cell is fundamentally governed by the capability of the surface to sustain the reaction without electron trapping or recombination by photogenerated charge. This work addresses the role of different modifiers on the overall photocurrent response, which allowed a dual material insertion, increasing the charge separation without compromise the surface catalysis. Sn-addition onto hematite electrodes clearly increased flat band potential, promoting a good charge separation and shifting the onset to a higher potential, attributed to the surface trapping state created by this modification. Notoriously, Sn-hematite electrode loaded with NiFeOx exhibited the highest photocurrent density, suggesting a partially recovered surface trapping states created during the electrode designing. The well-known co-catalyst acted in the overall photoelectrocatalytic response with no significant effect on the turn-on voltage, in other words, with minor effect related to catalytic efficiency. The dual modification contributes to understand the role of different modifiers allowing to satisfactorily improve charge separation while maintaining the conductivity attributed to intermetallic ions.