Supersaturated Doping-Induced Maximized Metal–Support Interaction for Highly Active and Durable Oxygen Evolution

Metal-support interaction (MSI) is pivotal and ubiquitously used in the development of next-generation catalysts, offering a pathway to enhance both catalytic activity and stability. However, owing to the lattice mismatch and poor solubility, traditional catalysts often exhibit a metal-on-support heterogeneous structure with limited interfaces and interaction and, consequently, a compromised enhancement of properties. Herein, we report a universal and tunable method for supersaturated doping of transition-metal carbides via strongly nonequilibrium carbothermal shock synthesis, characterized by rapid heating and swift quenching. Our results enable ∼20 at. % Ni₂FeCo doping in Mo₂C, significantly surpassing the thermodynamic equilibrium limit of <3 at. %. The supersaturation ensures more catalytically active NiFeCo doping and sufficient interaction with Mo₂C, resulting in the maximized MSI (Max-MSI) effect. The Max-MSI enables outstanding activity and particularly stability in alkaline oxygen evolution reaction, showing an overpotential of 284 mV at 100 mA cm^-2 and stable for 700 h, while individual Ni₂FeCo and Mo₂C only last less than 70 and 10 h (completely dissolved), respectively. In particular, the SD-Mo₂C catalyst also exhibits excellent durability at 100 mA cm^-2 for up to 400 h in 7 M KOH. Such a significantly improved stability is attributed to the supersaturated doping that led to each Mo atom strongly binding with adjacent heteroatoms, thus elevating the dissolution potential and corrosion resistance of Mo₂C at a high current density. Additionally, the highly dispersed NiFeCo also facilitates the formation of dense oxyhydroxide coating during reconstruction, further protecting the integrated catalysts for durable operation. Furthermore, the synthesis has been successfully scaled up to fabricate large (16 cm²) electrodes and is adaptable to nickel foam substrates, indicating promising industrial applications. Our strategy allows the general and versatile production of various highly doped transition-metal carbides, such as Ni₂FeCo-doped TiC, NbC, and W₂C, thus unlocking the potential of maximized or adjustable MSI for diverse catalytic applications.