Electronically differentiated tri-active sites of PtCoNi-derived heterophase locked up within CNTs for acidic/alkaline HER at industrial current density

Single-site hydrogen evolution reaction catalysts, including alloy nanoparticles and isolated single atoms, often face trade-offs among activity, stability, and pH adaptability. Alloying noble metals with transition metals can tune hydrogen adsorption and reduce Pt usage, yet Co/Ni-based alloys are prone to dissolution in acidic media. Meanwhile, single-atom catalysts maximize metal utilization but lack cooperative neighboring sites for multi-step HER, particularly water activation in alkaline conditions. Herein, we report a MOF-derived tri-active-sites of PtCoNi-derived heterophase integrating Pt_0.5Co_0.25Ni_0.25 alloy nanoparticles, Pt single atoms embedded in Co_0.5Ni_0.5 matrices, and atomically dispersed Co/Ni–N_x sites locked up within nitrogen-doped carbon nanotubes with only ∼5 wt% Pt loading. The catalyst exhibits outstanding HER activity, requiring only 14 mV and 17 mV to reach 10 mA cm⁻² in 0.5 M H₂SO₄ and 1.0 M KOH, respectively, outperforming commercial Pt/C. Density functional theory calculations reveal that the coexistence of these electronically differentiated sites balances hydrogen adsorption and water activation across pH. When integrated into a PEM electrolyzer, the catalyst delivers 1.0 A cm⁻² at 1.70 V and operates stably for 1000 h at 60 °C. Technoeconomic analysis indicates a hydrogen production cost of ∼$0.834 per GGE, highlighting its promise for cost-effective green hydrogen generation.