Dual confinement of RuOx nanoparticle using polar MnNiO and armored carbon for boosting water electrolysis

The poor stability of nanoparticle catalysts with catalytic activity is a significant obstacle to their industrial application. The establishment of rational nanoparticle structures to elucidate the relationship between catalyst structure and its catalytic activity and stability is crucial for constructing nanoparticle catalysts that are both highly active and stable. We propose a strategy to construct a dual-confinement effect of the nanoparticle, specifically by regulating the polarization of the MnNiO support to enhance strong oxide-support interactions (SOSI) and encapsulating the outer layer of nanoparticles with a carbon shell, which has been proven effective in improving the activity and stability of nanoparticle-based oxygen evolution reaction (OER) electrocatalysts. At a current density of 100 mA cm, the armor C@RuO@MnNiO catalyst displays an overpotential of 260 mV for the OER. After the OER test for 100 h, the current density of C@RuO@MnNiO shows no significant decay, whereas that of RuO@MnNiO and RuO@MnO rapidly decreases, indicating significant catalytic activity and stability of the catalyst. The assembled C@RuO@MnNiO||Pt/C electrode demonstrates excellent alkaline water electrolysis performance in an MEA electrolyzer, requiring only a low cell voltage of 1.76 V to achieve an ampere-level current density of 1 A cm. In-situ electrochemical Raman spectroscopy reveals the significant interaction between nanoparticles and the polar support. The reduction in Gibbs free energy, which establishes the rate-determining step (RDS) of OER, is caused by the charge redistribution caused by polar Mn doping in RuO@MnNiO and the coordination structure modifications, as shown by density functional theory calculations. This work provides an approach to designing efficient and stable nanoparticle electrocatalysts through the dual-confinement effect of SOSI-induced strong interactions and armor carbon layers.