Rapid reconstruction of nickel iron hydrogen cyanamide with in-situ produced proton acceptor for efficient oxygen evolution

Abstract

Metal oxyhydroxide (MOOH) through irreversible reconstructed fabrication from transition metal compounds are highly efficient oxygen evolution reaction (OER) electrocatalysts but face limits from adsorption energy scaling relationship and sluggish deprotonation kinetics. Herein, we present Fe-doped nickel hydrogen cyanamide (Ni0.8Fe0.2-HC), which is rapidly surface reconstructed into Ni0.8Fe0.2(OOH)-HC after OER. In-situ Raman spectroscopy and density functional theory (DFT) calculations, revealed that under OER conditions, -HNCN- converts into -NCN- ligand incorporating its abundant and uniform distribution across the active sites. DFT calculations further indicate that Fe predominantly acts as the active site, with -NCN- ligands contribute to the OER by facilitating the deprotonation of *OH in the rate-determining step (RDS), acting effectively as proton acceptor. The ensemble effect between Fe and -NCN- ligand forms the foundation of the exceptional electrocatalytic performance of Ni0.8Fe0.2(OOH)-HC (190 mV at 20 mA·cm−2). This discovery offers insights for designing innovative MOOH pre-catalysts to enhance OER efficiency.