High-valence chromium accelerated interface electron transfer for water oxidation.

An effective pathway to cope with the sluggish oxygen evolution reaction (OER) is to accelerate the electron transfer kinetics. Transition metal with high valence states doping can accelerate the reaction kinetics to afford high inherent activity. Herein, a novel trimetallic NiFeCr nanoalloy as an OER electrocatalyst is synthesized by replacing partial Fe in the Ni₃Fe alloy with Cr. In the OER process, Cr leached from the surface layer of the NiFeCr alloy to form a core–shell NiFeCr@NiFeOOH structure. The electrons from the OER intermediates were significantly accelerated by the high-valence Cr⁶⁺ as an electron acceptor at the core–shell interface. As a result, NiFeCr@NiFeOOH exhibited excellent OER performances with a low overpotential of 209 mV at 25 mA cm⁻² in 1.0 M KOH on conductive carbon paper, outperforming the Ni₃Fe alloy without Cr doping. Our work provides a new strategy to design and synthesize the NiFe-based alloy with high OER activity. [ABSTRACT FROM AUTHOR]