Rational engineering of the catalyst-electrolyte interface where the electrochemical processes occur to facilitate the proton transfer kinetics is crucial in various electrochemical reactions. Here, we show that the long-term stability of acidic oxygen evolution reaction (OER) catalyzed by RuO2 can be significantly promoted by engineering the interfacial water structure through interstitial boron (B) insertion (B-RuO2). Experimental results including in situ attenuated total reflectance-surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), local pH monitoring, and ab initio molecular dynamics (AIMD) simulations demonstrate that the insertion of boron atoms into the RuO2 lattice could facilitate the diffusion of protons across the interface by enhancing the connectivity of hydrogen-bond networks, thereby suppressing the continuous oxidative collapse of Ru. Moreover, the interstitial boron insertion could induce interfacial water reorientation and move nonbonding oxygen (ONB) away from Fermi level (Ef), resulting in decreased ONB and suppressed nucleophilic attack by interfacial H2O on ONB, further preventing structural corrosion caused by lattice oxygen loss. Consequently, the obtained B-RuO2 shows remarkable long-term operational stability, demonstrating over 1000 h of continuous operation at 10 mA cm-2. When applied in a practical proton exchange membrane water electrolyzer (PEMWE), it achieves a high current density of 3.0 A cm-2 at a voltage of 1.752 V and maintains stable performance at 4 A cm-2 for 200 h. This work provides a novel strategy for regulating the proton diffusion kinetics through engineering the interfacial water structure to promote acidic OER performance.
Zhu et al. (2025) studied this question.