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

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<i>_n</i>/(Ni,Co)(OH)_<i>x</i> catalyst with Pt single atoms (Pt₁) and Pd nanoclusters (Pd<i>_n</i>) anchored on OH-vacancy(V_OH)-rich (Ni,Co)(OH)_<i>x</i> nanoparticles create synergistic triadic active sites, allowing for methanol-enhanced low-voltage H₂ generation. For MOR, OH* is preferentially adsorbed on Pd<i>_n</i> 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)_<i>x</i>. 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<i>_n</i>, and OH-vacancy sites on (Ni,Co)(OH)_<i>x</i> create an "acid-base" microenvironment to facilitate water adsorption and splitting, forming H* species on Pt₁ and Pd<i>_n</i>, and *OH at the vacancy, to promote efficient H₂ evolution from the asymmetric Pt₁ and Pd<i>_n</i> 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.