“d-electron interactions” induced CoV2O6–Fe–NF for efficient oxygen evolution reaction

Abstract

The investigation of cost-effective, highly efficient, and environmentally friendly non-noble-metal-based electrocatalysts is imperative for oxygen evolution reactions (OER). Herein, CoV₂O₆ grown on nickel foam (NF) was selected as the fundamental material, and Fe²⁺ is introduced through a simple Fe³⁺ immersion treatment to synthesize CoV₂O₆–Fe–NF. Fe²⁺ is transformed into high oxidation state Fe^(2+δ)+ due to interactions between the 3d electrons of transition metals. In situ Raman spectroscopy analysis reveals the specific process of OER in the presence of Fe^(2+δ)+. Being in a higher oxidation state, Fe^(2+δ)+ provides more active sites, which is beneficial for the reaction between water molecules and the reactive sites of the electrocatalyst, ultimately enhancing the accelerated OER process. CoV₂O₆–Fe–NF exhibited an overpotential of only 298 mV at 100 mA cm⁻² in 1 M KOH electrolyte, which is lower than that of CoV₂O₆–NF (348 mV), as well as the comparative samples: Fe–NF (390 mV) and NF (570 mV). The exploration of high performance, triggered synergistically by the cooperative effect of transition metal 3d electrons, provides insights into the design of transition metal electrocatalysts for highly efficient OER.