Optimization of synthesis conditions for enhanced hydrogen evolution reaction performance in Fe-CoP@NC/N-rGO electrocatalysts

Hydrogen, a clean and renewable energy carrier, presents a promising alternative to fossil fuels. This work investigated the synthesis of Fe-CoP@NC/N-rGO hybrid composites derived from ZIF-67 metal-organic frameworks (MOFs) for efficient hydrogen production via electrochemical water splitting. The influence of microstructures on the electrocatalytic activity for the hydrogen evolution reaction (HER) was systematically investigated. Various characterization techniques, including FESEM, XRD, BET, Raman spectroscopy, UV-vis spectroscopy, TEM, AAS and XPS, were employed to analyze the morphology, crystallinity, composition, and surface properties of the synthesized electrocatalysts. The electrochemical performance and stability of the electrocatalysts were evaluated using linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The optimized Fe-CoP@NC/N-rGO composite exhibited exceptional HER performance with a low overpotential (eta = 84 mV) at 10 mA.cm(-2), a Tafel slope (beta) of 44 mV.dec(-1), and excellent stability over a 15-h lifespan. The low charge transfer resistance (Rct = 31 Omega) and high double-layer capacitance (Cdl = 81 mF.cm(- 2)) highlight the efficient charge transfer kinetics of the composite. This work emphasized the exceptional HER electrocatalytic activity attributed to the synergistic effects of strategic structural engineering, such as transition metal doping, phosphorization, and reduced graphene oxide (rGO) incorporation, coupled with high graphitization degree and appropriate heteroatom doping.