Carbon-encapsulated nickel-iron nanoparticles supported on nickel foam as a catalyst electrode for urea electrolysis

- Electrochemical process can purify the urea-rich wastewater, producing hydrogen gas.
- Carbon-encapsulated nickel iron nanoparticles (CE-NiFe) are prepared by pyrolysis.
- An ultra-thin layer of CE-NiFe nanoparticles is attached to the 3D Ni foam.
- CE-NiFe nanoparticles escalate both the urea electrolysis and hydrogen evolution.

A cyanide-bridged bimetallic coordination polymer, nickel hexacyanoferrate, could be pyrolyzed to form carbon-encapsulated nickel-iron (CE-NiFe) nanoparticles. The formation of nitrogen-doped spherical carbon shell with ordered mesoporous structure prevented the structural damage of catalyst cores and allowed the migration and diffusion of electrolyte into the hollow carbon spheres. An ultra-thin layer of CE-NiFe nanoparticles could be tightly attached to the three-dimensional macroporous nickel foam (NF) by electrophoretic deposition. The CE-NiFe nanoparticles could lower the onset potential and increase the current density in anodic urea electrolysis and cathodic hydrogen production as compared with bare NF. Macroporous NF substrate was very useful for the urea electrolysis and hydrogen production, which allowed for fast transport of electron, electrolyte, and gas products. The superior electrocatalytic ability of CE-NiFe/NF electrode in urea oxidation and water reduction made it favorable for versatile applications such as water treatment, hydrogen generation, and fuel cells.

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