Regulating Reconstruction-Engineered Active Sites for Accelerated Electrocatalytic Conversion of Urea

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalysts with high Ni content are promising for urea oxidation reaction (UOR).
• Inhibiting over-oxidation and toxic nitrite formation is crucial for efficient nitrogen cycling.
• Current methods often lead to inefficient nitrogen utilization.

Purpose of the Study:

• To develop a mediation engineering strategy to boost high-value nitrite formation from UOR.
• To enable a closed-loop system for a nitrogen economy.
• To investigate the catalytic mechanism for enhanced nitrite production.

Main Methods:

• Synthesis of platinum-loaded nickel phosphides (Pt-Ni2P) catalysts.
• Electrochemical testing in a Zn-urea-air battery and membrane electrode assembly (MEA).
• In situ spectroscopic characterizations and computational calculations.

Main Results:

• Pt-Ni2P catalysts achieved a nitrite production rate of 0.82 mol kWh⁻¹ cm⁻².
• Demonstrated high stability over 66 h in a Zn-urea-air battery and 135 h in an MEA system.
• Identified enriched dynamic Ni³⁺ active sites and the cyanate pathway as key to facilitated urea oxidation kinetics.

Conclusions:

• The proposed mediation engineering strategy effectively promotes high-value nitrite formation.
• Pt-Ni2P catalysts offer a promising solution for efficient UOR and nitrogen utilization.
• C-N cleavage is confirmed as the rate-determining step for nitrite generation.