Enhancing catalytic activity of Fe3O4 for electrochemical water oxidation via the coupling of OER-inert Au

Abstract

Interfacial charge transfer efficiency and electronic states of active sites are two essential issues to restrict catalytic activity of electrocatalysts for oxygen evolution reaction (OER). In this work, we show that although Au is recognized to be inert towards OER, the catalytic activity of Fe3O4 catalyst for OER was highly boosted by coupling Fe3O4 with Au to address these two issues. Here, Au nanoparticles were attached to hierarchical Fe3O4 microsphere through electrochemical deposition, a mild and rapid approach that can be accomplished within 3 min and requires no sophisticated equipment. With the coupling of Au, interfacial charge transfer resistance of Fe3O4 declined remarkably. On the other hand, oxidability of Fe sites and electron accepting capability of Au sites was elevated due to strong interaction between Au and Fe3O4. Owing to these two merits induced by Au, Fe3O4 exhibited enhanced catalytic activity for OER. The potential of Fe3O4 to obtain 10 mA/cm2 decreased by 640 mV, the current density was amplified up to 2.5 fold at the potential of 2 V (vs SCE), and the Tafel slop was reduced by 146 mV/dec.