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 (Ni1Ru1/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(metal)(-1) and superior HER activity, with an overpotential (eta) of only 16 mV for achieving a cathodic HER current of 10mAcm(-2), together with a high turnover-frequency of 1.88 s(-1) (@eta=30 mV). Additionally, the HOR limiting current of the Ni1Ru1/C nanotwins can be maintained up to a break-down potential of 0.25V(RHE), 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 adsorbed hydrogen (H-ad) and the adsorbed hydroxyl (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.

Automated summary

Here, Ni-Ru nano-twins (Ni1Ru1/C) were reported as a superior bifunctional catalyst for hydrogen oxidation/hydrogen evolution reaction (HOR/HER). The Ni1Ru1/C nano-twins exhibit remarkable HOR activity, comparable to Pt/C, and superior HER activity. The excellent electrochemical stability of the Ni1Ru1/C nanotwins was also demonstrated. Experimental and theoretical studies showed that the electron re-distribution at the Ni/Ru interface of Ni-Ru nano-twins optimizes the binding energy of intermediates, enabling the HOR/HER to proceed via a low energy barrier.