Accelerated Proton Transfer in Asymmetric Active Units for Sustainable Acidic Oxygen Evolution Reaction

Abstract

The poor durability of Ru-based catalysts limits the practical application in proton exchange membrane water electrolysis (PEMWE). Here, we report that the asymmetric active units in Ru 1– x M x O 2 (M = Sb, In, and Sn) binary solid solution oxides are constructed by introducing acid-resistant p-block metal sites, breaking the activity and stability limitations of RuO 2 in acidic oxygen evolution reaction (OER). Constructing highly asymmetric Ru–O–Sb units with a strong electron delocalization effect significantly shortens the spatial distance between Ru and Sb sites, improving the bonding strength of the overall structure. The unique two-electron redox couples at Sb sites in asymmetric active units trigger additional chemical steps at different OER stages, facilitating continuous proton transfer. The optimized Ru 0.8 Sb 0.2 O 2 solid solution requires a superlow overpotential of 160 mV at 10 mA cm –2 and a record-breaking stability of 1100 h in an acidic electrolyte. Notably, the scale-prepared Ru 0.8 Sb 0.2 O 2 achieves efficient PEMWE performance under industrial conditions. General mechanism analysis shows that the enhanced proton transport in the asymmetric Ru–O–M unit provides a new working pathway for acidic OER, breaking the scaling relationship without sacrificing stability.