Electronegativity-Induced Valence State Augmentation of Ni and Co through Electronic Redistribution between Co-Ni₃N/CeF₃ Interfaces for Oxygen Evolution Reaction

The development of high-performance and inexpensive electrocatalysts for the oxygen evolution reaction is one of the most desired objectives in energy conversion reactions. Due to sluggish reaction kinetics, the commercialization of such processes could not be achieved yet. Choosing an appropriate coupling interface to boost the catalyst performance is essential for the creation of high-efficiency electrocatalysts. Herein, metal-nitride and metal-fluoride heterostructures are reported with an extremely low overpotential of 180 mV at a current density of 10 mA cm –2 for OER application. The Co–Ni 3 N/CeF 3 catalyst shows strong interfacial interaction, causing significant electronic redistribution between Co–Ni 3 N and CeF 3 phases. X-ray photoelectron spectroscopy studies reveal the charge transfer from the Co–Ni 3 N to the CeF 3 phase, resulting in the augmentation in the valence states of Co and Ni and making them highly active sites for the adsorption of intermediates (O*, OH*, and HOO*). This phenomenon is possibly driven by the high polarity of CeF 3 due to the presence of highly electronegative F atoms. The stability study of the catalyst was performed for 120 h at large current densities of 100 and 200 mA cm –2 . The detailed analysis of the surface reconstruction of Co–Ni 3 N/CeF 3 is also carried out after a long-term stability test. This work offers a fresh look at the possibilities of the design and fabrication of an efficient and low-cost catalyst.