Hydrogen has been a promising sustainable alternative energy for mitigating the severity of fossil fuel deficiency. Among various hydrogen generation methods, urea electro-oxidation is considered to be the most economic approach to generate hydrogen meanwhile solving urea pollution. However, this technique is severely impeded by the sluggish 6-electron transfer process. Hence, to develop an efficient UOR electrode is of great importance.

In this work, economic silica modified nickel@carbon Ni/SiO₂-C electrode (Ni/SiO₂-C) 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, different types of template and carbon...[ Read more ]

Hydrogen has been a promising sustainable alternative energy for mitigating the severity of fossil fuel deficiency. Among various hydrogen generation methods, urea electro-oxidation is considered to be the most economic approach to generate hydrogen meanwhile solving urea pollution. However, this technique is severely impeded by the sluggish 6-electron transfer process. Hence, to develop an efficient UOR electrode is of great importance.

In this work, economic silica modified nickel@carbon Ni/SiO₂-C electrode (Ni/SiO₂-C) 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, different types of template and carbon precursors were used to synthesize carbon sponge. 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.