Phase Transformation from Amorphous RuS x to Ru-RuS 2 Hybrid Nanostructure for Efficient Water Splitting in Alkaline Media.

Ruthenium (Ru)-based materials, as a class of efficient hydrogen evolution reaction (HER) catalysts, play an important role in hydrogen generation by electrolysis of water in an alkaline solution for clean hydrogen energy. Hybrid nanostructure (HN) materials, which include two or more components with distinct functionality, show better performance than their individual materials, since HN materials can potentially integrate their advantages and overcome the weaknesses. However, it remains a challenge to construct Ru-based HN materials with desired crystal phases for enhanced HER performances. Herein, a series of new Ru-based HN materials (t-Ru-RuS 2 , S-Ru-RuS 2 , and T-Ru-RuS 2 ) through phase engineering of nanomaterials (PEN) and chemical transformation are designed to achieve highly efficient HER properties. Owing to the plentiful formation of heterojunctions and amorphous/crystalline interfaces, the t-Ru-RuS 2 HN delivers the most outstanding overpotential of 16 mV and owns a small Tafel slope of 29 mV dec -1 at a current density of 10 mA cm -2 , which exceeds commercial Pt/C catalysts (34 mV, 38 mV dec -1 ). This work shows a new insight for HN and provides alternative opportunities in designing advanced electrocatalysts with low cost for HER in the hydrogen economy.