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

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.