Electronic Modulation of Interfacial Engineering Co ₂ P@FeP-FeP ₄ Nanoframe Heterostructures Boosting Overall Water Splitting

The development of bifunctional electrocatalysts using renewable electricity for sustainable green energy industrial production is a potential method. As a result, numerous standard methodologies investigate developing electrocatalysts that naturally alter the electronic structure and minimize kinetic barriers. This study developed a promising method for engineering interfacial heterostructure nanoframes (Co2P/FeP-FeP4, hereafter denoted as CFP-8) deposited on nickel foam using hydrothermal and low-temperature phosphorization techniques. However, the improved CFP-8 electrocatalyst was exposed to abundant active sites and nanocrystals that remained intact. Importantly, P incorporation plays a crucial role in creating a P vacancy defect, which contributes to the thermodynamic favoring of the electrocatalysis of the oxygen evolution reaction (OER) and intrinsically enhances the hydrogen adsorption-free energy in hydrogen evolution reactions (HERs), due to the interconnected arrangement of CFP-8 nanoframes via the synergistic and strain-induced effect. Therefore, enclosed CFP-8 nanoframes demonstrate good performance and display low overpotential with high current densities (HER, η10 = 97 mV, η20 = 131 mV, η50 = 186 mV; OER, η10 = 230 mV, η20 = 247 mV, η50 = 280 mV) with a minimal Tafel value of η10 = 111 mV/dec and η10 = 74 mV/dec for HER and OER under alkaline medium, superior to benchmark electrocatalysts. Also, CFP-8 demonstrated remarkable stability over 50 h, utilizing chronoamperometry (CA) and chronopotentiometry (CP). In addition, an integrated electrolyzer using CFP-8/NF electrodes (polymeric binder-free electrodes) delivered a cell voltage of 1.65 V with a current density of 20 mA cm–2 with accelerated kinetics and improved stability, outperforming Pt/C (cathode)||RuO2 (anode) for overall water splitting reactions (OWSRs). The coexistence of Co, Fe, and P elements may accelerate electron and mass movement, improving the high current density electrocatalytic performance. This method paves the way for further research into low-cost transition metal-based phosphides for bifunctional energy applications.