PtRu nanocubes as bifunctional electrocatalysts for ammonia electrolysis

Co-regulation of the crystal plane and composition is a powerful strategy to effectively enhance the catalytic properties of nanomaterials. Herein, high-quality PtxRu nanocubes (PtxRu-NCs) with an adjustable composition and exposed (100) planes are synthesized by a simple hydrothermal method. For the ammonia electrooxidation reaction (AOR), Pt6Ru-NCs show obviously higher mass activity (192 mA mgPt−1) and specific activity (1.02 mA cm−2) than other PtxRu-NCs, Pt-NCs and commercial Pt nanocrystals. Density functional theory calculations demonstrate that the Pt6Ru (100) plane is more energetically favourable for the AOR than the Pt (100) plane due to the stronger binding of *NH2 and *NH. For the hydrogen evolution reaction (HER), the optimized Pt6Ru-NCs also deliver the smallest overpotential (37.6 mV) at 10 mA cm−2. The high activity of bifunctional Pt6Ru-NCs for both AOR and HER can be attributed to the crystal surface effect and Pt-Ru bimetallic interactions. A symmetric ammonia electrolyzer constructed here with Pt6Ru-NCs as the cathode and anode only requires 0.72 V electrolysis voltage for electrochemical hydrogen production.