MPhil Thesis Presentation - Development of Carbonaceous Sponge-based Nickel Electrode System for Urea Remediation

Economic Ni/SiO2-C electrode is synthesized by a simple impregnation method in addition with nickel electrodeposition. The obtained electrodes were used as anode for urea electro-oxidation to get clean gas energy. To optimize the carbon skeleton of electrodes, research used different types of template and carbon precursors to synthesis the carbon sponge. And the carbonization temperature was explored as well. The silica pellet with varying quantities and sizes was added to the skeleton to study the effect of Si on the nickel catalyst. The characterization and performances of Ni/SiO2-C were investigated through energy dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The Ni/SiO2-C electrode shows porous free-standing structure and a large electrochemical surface area (ECSA). Considerably, the Ni/SiO2-C electrode represents a higher electrocatalytic activity and selectivity in urea oxidation reaction (UOR) compared to a Ni@carbon electrode that synthesized by the same method. The results of CVs show that Ni/SiO2-C-7 electrode achieves a peak current density of 141.8 mA cm-2 at 0.6V (vs. Ag/AgCl) in 1 mol L-1 KOH with 0.1 mol L-1 urea solution, which is 2.5 times higher than that of Ni@carbon electrode (56.65 mA cm-2). And the selectivity of Ni/SiO2-C-7 in UOR achieves 90% at 0.6V (vs. Ag/AgCl). The economic efficiency and selectivity of Ni/SiO2-C electrode make it a promising material for large-scale urea electrolysis system, as well as hydrogen production.