Robust and Highly Efficient Electrochemical Hydrogen Production from Hydrazine-Assisted Water Electrolysis Enabled by the Metal-Support Interaction of Ru/C Composites

Hydrazineoxidation-assisted water electrolysis provides a promisingway for the energy-efficient electrochemical hydrogen (H-2) and synchronous decomposition of hydrazine-rich wastewater, butthe development of highly active catalysts still remains a great challenge.Here, we demonstrate the robust and highly active Ru nanoparticlessupported on the hollow N-doped carbon microtube (denoted as Ru NPs/H-NCMT)composite structure as HER and HzOR bifunctional electrocatalysts.Thanks to such unique hierarchical architectures, the as-synthesizedRu NPs/H-NCMTs exhibit prominent electrocatalytic activity in thealkaline condition, which needs a low overpotential of 29 mV at 10mA cm(-2) for HER and an ultrasmall working potentialof -0.06 V (vs RHE) to attain the same current density forHzOR. In addition, assembling a two-electrode hybrid electrolyzerusing as-prepared Ru NPs/H-NCMT catalysts shows a small cell voltageof mere 0.108 V at 100 mA cm(-2), as well as the remarkablelong-term stability. Density functional theory calculations furtherreveal that the Ru NPs serve as the active sites for both the HERand HzOR in the nanocomposite, which facilitates the adsorption ofH atoms and hydrazine dehydrogenation kinetics, thus enhancing theperformances of HER and HzOR. This work paves a novel avenue to developefficient and stable electrocatalysts toward HER and HzOR that promisesenergy-saving hybrid water electrolysis electrochemical H-2 production.

Automated summary

Hydrazine oxidation-assisted water electrolysis is a promising method for energy-efficient electrochemical hydrogen production and decomposition of hydrazine-rich wastewater. However, developing highly active catalysts remains challenging. In this study, we demonstrate the use of Ru nanoparticles supported on hollow N-doped carbon microtubes as bifunctional electrocatalysts for HER and HzOR. The hierarchical Ru NPs/H-NCMTs exhibit excellent electrocatalytic activity in alkaline conditions, with low overpotential for HER and HzOR. The assembled hybrid electrolyzer using Ru NPs/H-NCMT catalysts shows low cell voltage and remarkable stability. Density functional theory calculations reveal that Ru NPs serve as active sites for both HER and HzOR, enhancing their performances. This work provides a novel avenue for efficient and stable electrocatalysts for hydrogen production.