Ammonia mediated electrostatic adsorption synthesis of paired subnanoclusters with enhanced hydrogen oxidation performance

Sub-nanoclusters (sub-NCs) hold promise for the alkaline hydrogen oxidation reaction yet struggle with precise atomic dispersion and structural stability. Here, we report an ammonia-mediated electrostatic adsorption strategy that enables the synthesis of tunable paired metal-metal oxide sub-NCs, exemplified by PtSARuRh-MOx (SA represents single-atom sites, M = Cr, Mo, V, Ti, Ta, Zr). Electrostatic interactions between cationic PtRuRhδ+ and oxo-/fluoro-anions (e.g., CrO42−, MoO42-, VO3−, TiF62-, TaF72− and ZrF62−) control phase pairing during pyrolysis. The optimized PtSARuRh-CrOx demonstrates competitive mass activity (13.81 A mg−1, 58-fold that of commercial Pt/C) and delivers a peak power density of 1.43 W cm−2 in an alkaline membrane fuel cell, with stable operation exceeding 200 h. In situ spectroscopy and simulations reveal that the synergistic Ru/Rh sites, electronically modulated by the paired CrOx, collectively optimize H*/OH* adsorption and weaken CO* binding. This work establishes a generalizable synthetic route for the precise construction of paired sub-NCs for advanced energy conversion applications. Sub-nanoclusters hold great promise for alkaline hydrogen oxidation, yet achieving precise atomic control remains challenging. Here, the authors report an ammonia-mediated adsorption strategy to fabricate tunable paired sub-nanoclusters exhibiting good fuel cell performance and long-term durability.