Electric double layer overlapping effect in high-density sub-nanoclusters for enhanced acidic oxygen evolution reaction

Abstract

The electric double layer (EDL) overlapping between catalyst particles markedly modulates the local surface electric field, yet its influence on acidic oxygen evolution reaction (OER) performance remains elusive. Herein, we construct high-density ruthenium dioxide sub-nanoclusters (RuO₂-SCs) anchored on an amorphous boron–nitrogen–carbon (BNC) support (RuO₂-SCs/BNC) as a model, revealing that EDL overlapping between them elevates the compact layer potential at the catalyst surface. This physical field regulation synergistically enhances the H₃O⁺ concentration gradient and boosts intermediate coverage, thereby promoting the formation of the key *OOH intermediate and lowering the energy barrier of the rate-determining step. Concurrently, it stabilizes the Ru–O bonds and markedly mitigates the dissolution of ruthenium active sites. Leveraging these advantages, the catalyst demonstrates exceptional acidic OER performance, with a low overpotential of 142 mV to reach 10 mA cm⁻² and sustained stability for over 6300 hours. Moreover, it operates stably for 900 hours at 500 mA cm⁻² in proton exchange membrane water electrolysis. This work elucidates the EDL overlapping regulatory mechanism on acidic OER and provides a novel strategy to synergistically enhance electrocatalyst activity and stability.