Rational Design of ZIF-67−Derived CoNiMn Phosphide Nanosheets for Hydrogen Evolution

The design of earth-abundant electrocatalysts capable of driving the hydrogen evolution reaction (HER) across acidic, neutral, and alkaline electrolytes remains challenging. Here, ZIF-67-derived Co−Ni−Mn-containing phosphide nanosheet arrays were prepared directly on carbon cloth (nominally denoted CoNi2Mn3−P/CC). The optimized electrode delivers overpotentials of 77, 81, and 154 mV at 10 mA cm−2 in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M phosphate-buffered solution, respectively. After 60 h of potentiostatic operation, the reported current-retention values are 72.5%, 67.6%, and 70.1% in alkaline, acidic, and neutral media, respectively, revealing measurable long-term activity losses. In a two-electrode electrolyzer coupled with a FeOOH/(Ni1Co1)MoO4/CC anode, the catalyst reaches 10 mA cm−2 at a cell voltage of 1.54 V; a solar-panel-powered demonstration is also presented. Structural analyses identify CoP- and Mn2P-related crystalline features together with Ni-containing surface species, while density functional theory (DFT) calculations indicate that selected Co/Ni-containing model sites have favorable hydrogen adsorption free energies (ΔGH*). These findings illustrate a composition- and architecture-directed approach to self-supported HER electrocatalysts, while emphasizing the importance of verifying operational stability and the detailed local metal environments.