Nano-heterostructures of Partially Oxidized RuNi Alloy as Bi-functional Electrocatalysts for Overall Water Splitting.

Electrocatalytic water splitting as one of the most promising methods storing the renewable energy generated by intermittent sources, such as solar and wind energy, has attracted tremendous attention in recent years. Developing efficient, robust, and green catalysts for the hydrogen and oxygen evolution reactions (HER and OER) is of great interest. Here, we present a facile and green approach of producing RuNi/RuNi-oxide nano-heterostructures by controllable partial oxidation of RuNi nanoalloy, which is characterized and confirmed by various techniques, including high-resolution transmission electron microscopy and synchrotron-based X-ray absorption spectra. This nano-heterostructure demonstrates outstanding bi-functional activities for catalyzing the HER and OER which are both among the lowest reported values in the literatures. In a practical alkali-water splitting electrolyzer, it also achieves a record-low cell voltage of 1.42 V at 10 mA cm -2 current, significantly superior to commercial RuO 2 //Pt/C couple and other bi-functional water-splitting electrocatalysts presented previously. Density functional theory calculation is employed to elaborate the effect of Ni incorporation. This simple catalyst preparation approach is expected to be transferrable to other electrocatalytic reactions.