Activity and Stability of ZnFe2O4 Photoanodes under Photoelectrochemical Conditions

Photoelectrochemical (PEC) water splitting is a promising energy conversion and storage technology. The development requires highly active and stable photoanodes to perform the oxygen evolution reaction (OER). Here, we investigated the activity and stability of both pristine and hydrogen-treated ZnFe2O4. Using an illuminated scanning flow cell setup, we monitored the activity and dissolution rates of ZnFe2O4 under operando PEC conditions. It was found that under PEC water oxidation conditions, ZnFe2O4 does not degrade in basic pH. Moreover, thermally reduced ZnFe2O4 shows expected higher OER activity without compromising the stability compared to the pristine one. Dissolution of ZnFe2O4 was only observed once the applied potential was more cathodic than −0.1 V vs reversible hydrogen electrode as the surface Fe3+ is reduced regardless of illumination.