Abstract: In this work, a HEPF-PVP/CNT composite electrocatalyst with a three-dimensional interwoven network was successfully constructed by anchoring polyvinylpyrrolidone (PVP)-modified high-entropy perovskite fluoride (HEPF) nanoparticles onto pre-dispersed multi-walled carbon nanotubes (CNTs) via an in-situ nucleation and growth process during a one-pot solvothermal reaction. Serving as heterogeneous nucleation scaffolds, CNTs achieved uniform anchoring and high dispersion of HEPF nanoparticles, effectively overcoming the inherent defects of severe agglomeration and poor conductivity in pristine high-entropy fluorides. Microscopic characterizations revealed that the introduction of an optimal carbon skeleton (CNT-20) exerted a spatial confinement effect, significantly increasing the specific surface area and the exposure degree of active sites. Meanwhile, strong electronic coupling effects emerged at the hetero-interface, inducing the redistribution of electron clouds at metal centers, which increased the proportion of high-valence active sites such as Co3+ and Fe3+, and suppressed the generation of easily leachable Cr6+. Electrochemical tests demonstrated that the optimal HEPF-PVP/CNT-20 catalyst delivered a low overpotential of only 258 mV at a current density of 10 mA cm-2, with a Tafel slope of 85 mV dec-1, and showed only a 10.7 mV increase in overpotential after 120 h of continuous operation. This work provides a reliable structural engineering strategy for designing multi-metal synergistic electrocatalytic networks with high activity and long lifespan.

Key words: High-entropy perovskite fluorides, Carbon nanotubes; Oxygen evolution reaction, Interfacial electronic coupling, In-situ synthesis