Electrochemical overall water splitting (OWS) is a critical technology for the sustainable generation of high-purity hydrogen and oxygen using only water and renewable electricity. The development of Earth-abundant, bifunctional electrocatalysts capable of efficiently driving both the HER and the OER within a single system is imperative for the advancement of alkaline water electrolyzer technologies.
In this study, cobalt phosphide (CoP) and cobalt–iron phosphide (CoFeP) were successfully prepared on a copper substrate via an electroless deposition method using sodium hypophosphite (NaH₂PO₂) as the phosphorus source and the reducing agent. The anchoring of platinum (Pt) nanoparticles onto electrolessly deposited materials was achieved through the galvanic displacement technique. The morphology, composition, and crystallographic structure of the catalysts were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The bifunctional electrocatalytic performance of the materials for OWS was demonstrated in a two-electrode configuration using a 1 M KOH electrolyte.
Among the catalysts, Pt–CoFeP demonstrated superior bifunctional activity with a low cell voltage of 1.58 V at 10 mA cm-2 for overall water splitting, surpassing the performance of Pt–CoP due to the synergistic interactions between Co, Fe, and Pt. The incorporation of Fe into the system resulted in enhanced electrical conductivity and modulation of the electronic structure. Platinum decoration led to significant improvements in catalytic kinetics, a reduction in overpotentials, and the facilitation of efficient charge transfer at both electrodes. This work presents a scalable strategy for engineering platinum-modified transition metal phosphides as robust, high-performance bifunctional electrocatalysts for alkaline water electrolysis.
Acknowledgments
This research was funded by a grant (No. P-MIP-23-467) from the Research Council of Lithuania.
