Engineering of Unique Ni-Ru Nano-Twins for Highly Active and Robust Bifunctional Hydrogen Oxidation and Hydrogen Evolution Electrocatalysis

Herein, unique Ni-Ru nano-twins (NixRuy/C) are reported for the first time as a superior bifunctional catalyst for hydrogen oxidation/hydrogen evolution reaction (HOR/HER). Compared to Pt/C, the Ni1Ru1/C nano-twins display a remarkable HOR activity with a comparable mass activity of 0.12Amg-1metal and superior HER activity, with an overpotential (դ) of only 16mV for achieving a cathodic HER current of 10mAcm-2, together with a high turnover-frequency of 1.88s-1 (@դ=30mV). Additionally, the HOR limiting current of the Ni1Ru1/C nano-twins can be maintained up to a break-down potential of 0.25VRHE, demonstrating excellent electrochemical stability. Experimental and theoretical studies reveal that the electron re-distribution at the Ni/Ru interface of Ni-Ru nano-twins optimizes the binding energy of the Had and OHad intermediates, allowing the HOR/HER to proceed via a low energy barrier. This work provides a strategy to synthesize hetero-metal nano-twins as promising multi-functional catalysts and highlights the critical role of interfaces for heterostructured electrocatalysts.