Enhanced electrocatalytic OER performance of Ba/CS-CoFe₂O₄ ternary heterostructure catalyst: Experimental and theoretical insights

Herein, a ternary heterostructure catalyst Ba/CS-CoFe₂O₄ (barium/chitosan-doped Cobalt ferrite) was developed by a straightforward co-precipitation technique to investigate oxygen evolution reaction (OER) activity. Varying quantities (2 and 4 wt %) of Ba and a fixed amount (3 wt %) of CS were doped to modify the surface area, porosity, crystallite size, and stability of CoFe₂O₄. Comprehensive characterizations revealed multiple phases, polycrystalline behavior, enhanced absorption, structural defects, and nanorods overlapping nanoparticles (NPs) like the morphology of Ba/CS-CoFe₂O₄. Furthermore, the experimental results revealed that 2 wt % of Ba/CS-CoFe₂O₄ exhibited superior electrocatalytic activity with the highest kinetics and ECSA (electrochemically active surface area) for the OER process in 1 M KOH. To further elucidate the OER performance, density functional theory (DFT) calculations were conducted. The optimized CoFe₂O₄ structure was confirmed to have a cubic Fd-3m symmetry, with a calculated bandgap energy (E_g) of 1.62 eV, closely matching experimental data. Adsorption energy calculations showed that Ba/CS doping significantly improved the binding strength of OH intermediates on the CoFe₂O₄ (100) surface, highlighting the role of dopants in enhancing surface reactivity. These findings demonstrate the potential of Ba/CS doping to optimize the electronic, structural, and surface properties of CoFe₂O₄ for efficient OER electrocatalysis, paving the way for novel electrochemical catalyst design.