Re-construction with anion leaching of iron-based pre-catalysts for oxygen evolution

Abstract

Pre-catalysts that will evolve into catalytic active species during the catalytic process have got researchers’ much attention for oxygen evolution. The thus derived active species often show higher activity than those counterparts obtained by direct synthesis method. However, the complex reconstruction behavior usually restricts the understanding of catalytic process and limits their practical applications. In this study, an iron-based polyoxomolybdate (Fe-POMo) material obtained with the reaction between Fe3+ and [Mo7O24]6− was shown. The obtained Fe-POMo product presents porous and amorphous structure, which facilitates the diffusion-leaching of [Mo7O24]6− anions, and so the phase reconstruction in alkaline solution during oxygen evolution process. The resulted low-crystalline (oxy)hydroxides with amounts of vacancies are loaded on electrode surface through a dissolution-redeposition process, which act as the active substrates for catalysis. The optimized catalytic electrode from Fe-POMo precursor presents excellent catalytic activity and high stability for at least 48 h. This study shows a new route for the derivation of pre-catalysts with the formation of high active (oxy)hydroxides.