Subnanometric Pt-W Bimetallic Clusters for Efficient Alkaline Hydrogen Evolution Electrocatalysis

Rational design and synthesis of subnanometric bimetallic clusters (SBCs) within a narrow size distribution, along with achieving full SBCs exposure on supporting materials, are formidable challenges that must be overcome to realize potential applications. This work details a facile strategy to synthesize fully exposed PtW SBCs with an average size of 0.81 nm on the surface of spherical N-doped carbon (PtW/NC), which is underpinned by the electrostatic interactions between the negatively charged [H₃PtW₆O₂₄]^5- polyanions and the positively charged closed-pore metal-organic framework (MOF) [Zn₅(OH)₂(AmTRZ)₆]²⁺. The PtW/NC exhibits significant electrocatalytic performance and stability for the alkaline hydrogen evolution reaction with an ultralow overpotential of 4 mV at 10 mA cm^-2, a low Tafel slope of 29 mV dec^-1, and a long-term electrolysis stability exceeding 140 h. The Pt mass activity of PtW/NC is 34 times higher than that of commercial 20 wt % Pt/C at the 100 mV overpotential. Both theoretical calculations and electrochemical measurements indicate that a synergistic effect between Pt and W is responsible for this notable catalytic performance. The synthetic approach outlined in this work can be applied to other MOFs and coordination networks that lack pores or have limited porosity.