Lattice-Engineered Nickel Oxide for Electrocatalytic Urea Recycling with Near-Unity N₂ Selectivity.

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Science
• Catalysis

Background:

• Circulating nitrogen is vital for ecosystems, with urea being a key nitrogen compound.
• Environmental pollution from urea necessitates efficient nitrogen removal technologies.
• Electrochemical urea reforming offers a sustainable method to convert urea into nitrogen gas (N₂) and hydrogen (H₂).

Purpose of the Study:

• To address the challenge of low N₂ selectivity in electrochemical urea reforming.
• To uncover a novel urea oxidation pathway for highly selective N₂ production.
• To develop advanced catalytic materials for efficient urea splitting.

Main Methods:

• Investigated urea oxidation pathways using nickel oxide (NiO) lattices with adjacent Ni sites.
• Employed lattice engineering through aluminum (Al) substitution to optimize catalyst performance.
• Tested electrochemical urea reforming devices with synthetic urea and artificial urine.

Main Results:

• Discovered a urea oxidation pathway on NiO that favors intramolecular N-N coupling, enhancing N₂ selectivity.
• Achieved near-unity N₂ selectivity towards N-based products with Al-substituted NiO catalysts.
• Observed a tenfold increase in N₂ production rate compared to previously reported catalysts.

Conclusions:

• The developed NiO-based catalysts effectively split urea into N₂ and H₂, overcoming previous selectivity limitations.
• This technology provides a sustainable bridge between energy production and environmental remediation.
• The findings pave the way for practical electrochemical urea reforming devices addressing the water-energy-food nexus.