Co-doped Ni-Mo oxides: highly efficient and robust electrocatalysts for urea electrooxidation assisted hydrogen production

Electrolysis systems constructed by anodic urea oxidation reaction (UOR) and cathodic hydrogen evolution reaction (HER) have received considerable attention in sustainable energy and waste utilization. However, current electrolysis systems are far from the requirement of practical applications due to the limited catalytic activity and stability of the electrodes. Herein, we design a UOR electrode with Co-doped NiMoO4 treated in Ar (NCMO-Ar), which shows superior UOR performance because of the Co doping. On the other hand, the Co-doped NiMoO4 treated in H-2 (NCMO-H-2) delivers high activity for HER. Moreover, the use of a flow electrolysis cell is demonstrated with continuous injection of urea, which only requires a low operation potential of 1.342 V to reach 10 mA cm(-2), and shows no attenuation at a large operation current of 100 mA cm(-2) for 200 h. It is believed that this high-performance electrolysis system lays an important foundation in developing a practical electrolyzer for efficient and sustainable hydrogen production coupled with waste organic oxidation.

Automated summary

This study designs a UOR electrode with Co-doped NiMoO4 treated in Ar (NCMO-Ar) and a Co-doped NiMoO4 treated in H-2 (NCMO-H-2) for anodic urea oxidation reaction and cathodic hydrogen evolution reaction. A flow electrolysis cell with continuous urea injection is demonstrated, showing high-performance and stable operation.