Fe ³⁺ Ions as Catalytic Enhancers: Unveiling Their Impact on CoFeZIF for Electrocatalytic Oxygen Evolution Reaction

ABSTRACT The development of low‐cost, electrocatalysts for alkaline oxygen evolution reaction (OER) is essential to addressing water‐splitting challenges, with structural and phase modulation of MOFs being a critical yet complex aspect of catalyst design. In the present work, Fe 3+ induced amorphization, and its strong Lewis acid character are utilized to successfully deposit the c/a hybrid bimetallic CoFeZIFs on carbon paper (CP). CoFeZIF/CP demonstrates outstanding OER efficiency with a low overpotential of 338 mV @ 10 mA/cm 2 , having a Tafel slope of 62 mV dec −1 along with negligible change in current density during a 24‐h durability test. The high catalytic property is attributed to localized amorphization and the strong Lewis acid character of Fe 3+ , which makes Co more electron‐deficient to fascinate hydroxide ions. To uncover the interfacial structure dynamics and actual electrocatalytic species of the electrocatalyst, in situ Raman spectroscopy was carried out at various potentials. The combination of spectroscopic and XPS data led to the conclusion that CoOOH is the actual active species in the developed electrocatalyst, while the loss of characteristic peaks, peak broadening, and increased background in Raman spectra further supported its amorphization. This work provides a new way to design an electrocatalyst based on a c/a hybrid MOF structure exhibiting high OER efficiency.