In-situ generated Ni(OH)2 on chemically activated spent catalyst sustains urea electro-oxidation in extensive alkaline conditions

Electrochemical urea oxidation reaction (UOR) is an efficient way to produce cost-effective hydrogen from ureabased wastes. We show that a chemical modification involving partial oxidation of the spent catalyst consisting of Ni@CNT, generated from industrial methane decomposition plants, is found to augment sustained UOR activity for a prolonged time in extensive alkaline conditions. The activated catalyst, Ni(OH)2-Ni@CNT exhibits a TOF of 0.5 s-1 and Tafel slope of 30 mV/dec retaining UOR activity for 60 h at -75 mA/cm2 in 1.6 M urea and 6 M KOH. In-situ X-ray absorption spectroscopy reveals that Ni in the activated spent catalyst possesses an average oxidation state of -1.4 and Ni(OH)2 content gets enhanced from 26 % to 30 % during UOR representing fresh Ni (OH)2 formation. The activated Ni nanoparticles wrapped with carbon nanotubes provide excellent activity, COx removal, turnover frequency, and favors in-situ formation of fresh Ni(OH)2 responsible for the activity retention.