Stabilization of Active Ultrathin Amorphous Ruthenium Oxide via Constructing Electronically Interacted Heterostructure for Acidic Water Oxidation

Amorphous RuO_x (a-RuO_x) with disordered atomic arrangement and abundant coordinatively unsaturated Ru sites possesses high intrinsic electrocatalytic activity for oxygen evolution reaction (OER). However, the a-RuO_x is prone to fast corrosion during OER in strong acid. Here, we realized the stabilization of an ultrathin a-RuO_x layer via constructing heterointerface with crystalline α-MnO₂ nanorods array (MnO₂@a-RuO_x). Benefiting from the strong electronic interfacial interaction, the asformed MnO₂@a-RuO_x electrocatalyst display an ultralow overpotential of 128 mV to reach 10 mA cm^-2 and stable operation for over 100 h in 0.1 M HClO₄. The assembled proton exchange membrane (PEM) water electrolyzer reach 1 A cm^-2 at applied cell voltage of 1.71 V. Extensive characterizations indicate the MnO₂ substrate work as an electron donor pool to prevent the overoxidation of Ru sites and the OER proceeds in adsorbent evolution mechanism process without involving lattice oxygen. Our work provides a promising route to construct robust amorphous phase electrocatalysts.