Unlocking Efficient Electrochemical Urea Oxidation and Understanding Mechanism Insights of Co-Doped NiS

• Published in: ACS Engineering Au Vol. 5; no. 4; pp. 450 - 467
• Main Authors: Upadhyay, Prachi, Deka, Artina, Chakma, Sankar
• Format: Journal Article
• Language: English
• Published: American Chemical Society 20.08.2025
• Subjects: transition metal sulfide; urea electrooxidation; bimetallic catalyst
• ISSN: 2694-2488; 2694-2488
• DOI: 10.1021/acsengineeringau.5c00034

Urea electrooxidation serves as the core of urea-based fuel cells, urea electrolysis for energy generation, and urea-based wastewater treatment for environmental applications. This study emphasizes the development of electrocatalysts made from nickel–cobalt bimetallic sulfide, synthesized through an ultrasonic-assisted hydrothermal synthesis method, focusing on their capacity to oxidize urea under alkaline conditions. The objective was to reduce the onset potential for this reaction. These nickel–cobalt bimetallic sulfide catalysts were characterized by using various techniques, including X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A notable decrease in overpotential was observed: 70 mV for Ni0.75Co0.25S and 130 mV for Ni0.50Co0.50S, compared to a Ni1Co0S electrode. Furthermore, the XPS analysis indicates that the ratio of Ni3+/Ni2+ is higher for Ni0.75Co0.25S than for other combinations, with Ni3+ acting as the primary active center for urea electrooxidation. This reduction in the onset potential for urea oxidation and the increase in Ni3+ on the nickel–cobalt bimetallic sulfide electrodes reveal significant potential for future applications in urea electrooxidation.