Interfacial Engineering of Mn, Mo Co-doped Ni3S2/Ni7S6 from POM-MOF Gel for High-Performance pH-Universal Hydrogen Evolution.

The development of highly efficient, platinum-free electrocatalysts capable of driving the hydrogen evolution reaction (HER) over a broad pH range is essential for achieving sustainable and scalable hydrogen production. Herein, we report a polyoxometalate-metal-organic framework (POM-MOF) gel-derived dual metal-doped nickel sulfide electrocatalyst, denoted as Mn, Mo-Ni3S2/Ni7S6/nickel foam (NF), for pH-universal HER. The POM-MOF gel serves as a self-templating precursor, enabling homogeneous metal distribution, strong interfacial coupling, and controlled formation of a densely interconnected blades-of-grass-like nanoarchitecture during sulfurization. This gel network promotes the in situ generation of abundant Ni3S2/Ni7S6 heterointerfaces and uniform Mn and Mo co-doping. The synergistic effects of heterointerface engineering, hierarchical morphology, and dual-metal doping modulate the electronic structure, expose abundant active sites, and accelerate interfacial charge-transfer kinetics, thereby enhancing intrinsic HER activity. As a result, the Mn, Mo-Ni3S2/Ni7S6/NF catalyst exhibits superior HER performance, requiring overpotentials of only 52, 95, and 111 mV to achieve a current density of 10 mA cm-2 in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M PBS, respectively. The corresponding Tafel slopes are 32, 56, and 46 mV dec-1. The catalyst also exhibits 100 h durability in acidic and alkaline media, highlighting POM-MOF gel engineering for noble-metal-free HER catalysts.