Methanol-Enhanced Low-Cell-Voltage Hydrogen Generation at Industrial-Grade Current Density by Triadic Active Sites of Pt1–Pd<i>n</i>–(Ni,Co)(OH)<i>x</i>

Abstract

<p>Methanol (ME) is a liquid hydrogen carrier, ideal for on-site-on-demand H₂ generation, avoiding its costly and risky distribution issues, but this “ME-to-H₂” electric conversion suffers from high voltage (energy consumption) and competitive oxygen evolution reaction. Herein, we demonstrate that a synergistic cofunctional Pt₁Pd<em>_n</em>/(Ni,Co)(OH)_<em>x</em> catalyst with Pt single atoms (Pt₁) and Pd nanoclusters (Pd<em>_n</em>) anchored on OH-vacancy(V_OH)-rich (Ni,Co)(OH)_<em>x</em> nanoparticles create synergistic triadic active sites, allowing for methanol-enhanced low-voltage H₂ generation. For MOR, OH* is preferentially adsorbed on Pd<em>_n</em> and then interacts with the intermediates (such as *CHO or *CHOOH) adsorbed favorably on neighboring Pt₁ with the assistance of hydrogen bonding from the surface hydrogen of (Ni,Co)(OH)_<em>x</em>. The enhanced selectivity of the *CHOOH pathway, instead of *CO, sustains the MOR activity to a practically high current density. For HER, triadic Pt₁, Pd<em>_n</em>, and OH-vacancy sites on (Ni,Co)(OH)_<em>x</em> create an “acid–base” microenvironment to facilitate water adsorption and splitting, forming H* species on Pt₁ and Pd<em>_n</em>, and *OH at the vacancy, to promote efficient H₂ evolution from the asymmetric Pt₁ and Pd<em>_n</em> sites via the Tafel mechanism. The triadic-site synergy opens new avenues for the design and synthesis of highly efficient and stable cofunctional catalysts for “on-site-on-demand” H₂ production, here facilitated by liquid methanol.</p>