Fe-doped CoP nanoparticles anchored on rGO with synergistic enhancement for efficient HER/OER and water splitting

Abstract

For overcoming the intrinsic limitations of CoP in alkaline water splitting (irrational electronic structure, poor conductivity, and agglomeration-caused low active site utilization), this work puts forward a bifunctional optimization strategy: “Fe-doping electronic modulation coupled with rGO support synergistic enhancement”, which was achieved by synthesizing the Fe–CoP@rGO composite catalyst (Fe-doped CoP nanoparticles anchored on rGO) via a wet-chemical method and phosphidation. The introduction of Fe induces electron rearrangement by substituting Co atoms in the CoP lattice, which significantly increases the proportion of high-activity Co³⁺ sites and optimizes the adsorption energy barriers of *H/*OH intermediates. Meanwhile, the high conductivity of rGO enables the construction of an efficient electron transport network, and its large specific surface area inhibits nanoparticle agglomeration through steric hindrance, enhancing the electrochemical active surface area (ECSA) twice that of pure CoP. Bifunctional catalytic performance tests show that Fe–CoP@rGO achieves low overpotentials of 86.2 mV (HER) and 285 mV (OER) at 10 mA cm⁻², which are significantly superior to those of CoP@rGO. When assembled into an overall water splitting device, it only requires 1.61 V to reach 10 mA cm⁻², with no performance degradation after 24 h of continuous operation in 1 M KOH and a Faraday efficiency close to 100%. This study provides a clear structure–activity relationship and a scalable optimization pathway for designing high-performance and stable non-noble metal bifunctional electrocatalysts through the synergistic effect of electronic structure modulation and support function enhancement.