Highly porous nickel@carbon sponge as a novel type of three-dimensional anode with low cost for high catalytic performance of urea electro-oxidation in alkaline medium

Hollow Sodium Nickel Fluoride Nanocubes Deposited MWCNT as An Efficient Electrocatalyst for Urea Oxidation

“…Several materials, including noble and non-noble metals, metal oxides, and metal hydroxides, have been investigated as catalysts in the oxidation of urea [11,13,[18][19][20][21][22][23][24][25][26][27][28][29][30]. Ni was found to be the most favorable for electro-oxidation of urea [10].…”

Self‐Assembly Assisted Fabrication of Nanoporous Nickel (II) Phosphate Octahydrate Microspheres Catalyst with Orange Peel Surface toward Urea Oxidation

“…The deep impact of excess urea is readily apparent in a number of areas: the hydrolysis effect of additional urea; the loss of urea (fuel); the feeding of supporting electrolyte (KOH) and the blocking of NiP110 electrode by carbon dioxide. Since urea and hydroxide ions diffuse to the surface of electrode concurrently during the progress of fuel, oxidation current density is reduced with an unsuitable ratio of supporting electrolyte/fuel …”

Metal–organic framework–derived Ni@C and NiO@C as anode catalysts for urea fuel cells

“…7, as the urea concentration increased in the range of 0.1-0.33 M, the MPD reached a maximum and then decreased as the urea concentration further increased, which probably reflected the deactivation and/or blockage of the catalyst at such high concentrations. At a urea concentration of 0.5 M, a transition zone (i.e., decrease of current density) was observed in the polarization curve, indicating catalyst site blockage 33,38 . The formation of the transition zone was previously attributed to the sluggish www.nature.com/scientificreports www.nature.com/scientificreports/ kinetics and flooding of catalyst pores by water and products of urea electro-oxidation, which prevented urea molecules from reaching the catalyst sites 39,40 .…”