Superhydrophilic V‐Doped CoP Nanoparticles@Cu₃P Nanotubes with Vacancy and Interface Engineering for Synergistically Enhanced Electrocatalytic Overall Water Splitting

Abstract Synergistically optimizing electronic structure and exposing abundant active sites to significantly improve performance of transition metal‐based electrocatalysts is an urgent necessity and remains a significant challenge. Herein, a hybrid nanotubes array structure of rich P‐vacancy V‐CoP@Cu₃P in situ grown on copper foam (V_P‐V‐CoP@Cu₃P HNTAs/CF) is fabricated for overall water splitting. The combined experimental and theoretical calculations reveal that V doping‐induced vacancies lead to the formation of local electric field within V‐CoP and heterojunction‐induced built‐in electric field, which can jointly accelerate electron transfer and charge separation, thereby enhancing reaction kinetics. Moreover, the nanotube array structure can not only increase the electrochemical active surface area and offer superior mass transfer, but also possess the superhydrophilic nature enhancing the utilization efficiency of electrode surfaces. Due to these advantages, V_P‐V‐CoP@Cu₃P HNTAs/CF can provide distinguished HER and OER activity, and by employing V_P‐V‐CoP@Cu₃P HNTAs/CF as bifunctional electrocatalysts, the overall water splitting device delivered a current density of 10 mA cm⁻² at a low voltage of 1.46 V and maintained its activity without decay for 200 h in 1 m KOH electrolyte.