Exceptional Pt⁴⁺ ion substituted zinc cobaltite spinel oxide nanoelectrocatalysts for enhanced electrochemical hydrogen performance supported by DFT

Platinum-doped Zn spinel oxide coated Nickel foam (ZnPt_xCo_2-xO₄ (PtZnCo) @NF (x ≤ 0.08)) nano electrocatalysts were synthesized using the hydrothermal method. XRD studies confirmed the spinel oxide phase. The surface analysis illustrated two morphologies consisting of nanoneedles and nano feathers. The PtZnCo@NF (x ≤ 0.08) nanoelectrocatalyst exhibited exceptional performance in the HER, achieving a Tafel slope of 53.4 mV/dec, an overpotential of 94.4 mV, and outstanding stability over a longer period. The electrochemical tests revealed that the 6.0% Pt⁴⁺ concentration exhibited enhanced performance in the hydrogen evolution reaction (HER). The impact of Pt doping on ZnCo₂O₄ (PtZnCo) catalysts to improve their HER performance was investigated also using Density Functional Theory (DFT). The results show that Pt dopant, given its metallic character, modifies PtZnCo's electronic structures by shifting its Fermi level over the 0.84 eV bandgap as was observed for the ZnCo, hence improving its charge transfer ability better. According to the computed adsorption energies (E_A) for all active sites, Pt dopant increases H's adsorption on all sites while providing an additional active site, giving the PtZnCo modified catalyst overall faster kinetics towards HER.