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 Pt SA RuRh-MO x (SA represents single-atom sites, M = Cr, Mo, V, Ti, Ta, Zr). Electrostatic interactions between cationic PtRuRh δ+ and oxo-/fluoro-anions (e.g., CrO 4 2− , MoO 4 2- , VO 3 − , TiF 6 2- , TaF 7 2− and ZrF 6 2− ) control phase pairing during pyrolysis. The optimized Pt SA RuRh-CrO x 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 CrO x , 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.