Thermodynamic Controlled Atomic Pairing: A Potential Window Strategy for Precise Synthesis of Dual-Atom Electrocatalysts via Sequential Electrodeposition

Dual-atom catalysts (DACs) unlock exceptional catalytic potential through maximized atom utilization and synergistic effects, while their atomically precise synthesis remains challenging. Herein, we develop a scalable and atomically precise electrochemical strategy for fabricating precious-metal-based DACs through a potential window-controlled underpotential deposition (UPD) and galvanic replacement cascade. The primary metal sites act as thermodynamically favorable anchoring sites to guide the site-specific assembly of secondary metal atoms. Thermodynamic size screening, through control of the deposition potentials, can effectively exclude larger-sized impurities. This versatile approach is applicable to diverse metals (Pt, Pd, etc.) and tunable supports. As an example, the resulting asymmetrically configured Pt₂ DAC anchored on sulfur doped graphite foam (Pt₂/SGF) delivered outstanding hydrogen evolution reaction (HER) performance, exhibiting an overpotential of 24.2 mV at 10 mA cm^-2. Mechanistic studies reveal that the synergistic electron transfer within the Pt dimer optimizes hydrogen intermediate adsorption (Δ<i>G</i>_H* = -0.06 eV), thereby boosting the catalytic activity.