Deciphering and Suppressing Over‐Oxidized Nitrogen in Nickel‐Catalyzed Urea Electrolysis

Abstract

Urea electrolysis is ap rospective technology for simultaneous H 2 production and nitrogen suppression in the process of water being used for energy production. Its sustainability is currently founded on innocuous N 2 products; however,w ed iscovered that prevalent nickel-based catalysts could generally over-oxidizeu rea into NO 2 À products with % 80 %F aradaic efficiencies,p osing potential secondary hazards to the environment. Trace amounts of over-oxidized NO 3À and N 2 Owere also detected. Using 15 Nisotopes and urea analogues,w ed erived an itrogen-fate network involving aN O 2 À -formation pathwayv ia OH À -assisted C À Nc leavage and two N 2 -formation pathwaysv ia intra-and intermolecular coupling.D FT calculations confirmed that C À Nc leavage is energetically more favorable.I nspired by the mechanism, ap olyaniline-coating strategy was developed to locally enrich urea for increasing N 2 production by af actor of two.T hese findings provide complementary insights into the nitrogen fate in water-energy nexus systems.

Nickel‐Catalyzed Urea Electrolysis: From Nitrite and Cyanate as Major Products to Nitrogen Evolution

“…Furthermore, the IC traces of all reaction mixtures contained an additional peak, revealing that UOR led to the formation of another anionic product in high quantities (Figure 1c). In a recent report, this additional IC peak was assigned to carbonate [13b] . However, the IC system used in the present work was equipped with a suppressor for the carbonate anion (see product analysis details in Supporting Information, p. S2–S3), indicating that another anion was produced in a course of electrolysis.…”

Ultrafast synthesis of NiFe electrocatalysts via a Fenton-assisted corrosion strategy for alkaline water and urea oxidation

“…1d), attributed to the species of Ni 0 , Ni 2+ and Ni 3+ . 22 Significantly, the Ni chemical states of NiFe LDH-NF was a bit different from that of NF (21.4% vs. 23.1% for Ni 0 , 34.2% vs. 34.1% for Ni 2+ , and 44.4% vs. 42.8% for Ni 3+ ). In comparison, F-NiFe LDH-NF presented a promoted ratio of Ni 3+ species (47.6%), indicating more high oxidation states caused by the Fenton reaction ( e.g.…”

Ligand Vacancy Channels in Pillared Inorganic-Organic Hybrids for Electrocatalytic Organic Oxidation with Enzymatic Activities

“…3b). Urea electrolysis is a promising technique for the simultaneous hydrogen production and urea abatement, and an efficient urea oxidation catalyst is often a prerequisite for on-site urine treatment 47,48,49 . By using urea as a typical substrate, we further analyzed the electrochemical oxidation kinetics on our NiHC-pz-300 catalyst.…”