Mo Doping Induced Ni Surface Enrichment of Porous Spherical Core–Shell Bifunctional Electrocatalyst for Overall Water Splitting

Abstract Rational design of efficient and non‐noble metal bifunctional catalysts for alkaline overall water splitting (OWS) electrochemical reactions is of top priority in the development of hydrogen‐based energy. Constructing catalysts with unique structures to optimize the intrinsic activity is a promising strategy. In this work, a newly developed Ni₃Co₃Mo₁₀₀‐BTC‐15h catalyst consisting of Ni nanoparticles enriched on the surface along with a core‐shell porous structure is prepared via a hydrothermal process. Due to the unique composition and Ni‐enriched core–shell structure, the Ni₃Co₃Mo₁₀₀‐BTC‐15h catalyst exhibits enhanced electrocatalytic properties for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media. Under the dual tuning and intermetallic phase, the Ni₃Co₃Mo₁₀₀‐BTC‐15h catalyst deliver a lower overpotential of 151 mV and ≈ 136 mV exceeding commercial catalysts for OER and HER. When the Ni₃Co₃Mo₁₀₀‐BTC‐15h is used as bifunctional catalyst for OWS in a two‐electrode alkaline electrolyzer, a cell voltage of 1.62 V is required to drive 10 mA·cm⁻² comparable to that of commercial Pt/C and RuO₂ catalysts. This work proposes a potential strategy for optimizing the electrocatalytic performance of non‐noble metal catalysts for OWS.