Preparation of Ni/NiO-C catalyst with NiO crystal: catalytic performance and mechanism for ethanol oxidation in alkaline solution

Highly active and durable catalysts are imperative for the development of alcohol oxidation research. Herein, a Ni/NiO-C catalyst with hollow NiO crystal can be used in ethanol oxidation. The hollow NiO nanoparticles are absolutely coated in the amorphous carbon and the generated NiO crystal remarkably raises the electrocatalytic performances of catalysts. Among all samples, the Ni/NiO-C3 catalyst shows the highest current density in 0.5 M ethanol solution. This is mainly derived from the synergistic effect of the crystallographic form, carbon coating, and hollow structure. Besides, the reaction mechanism of Ni/NiO-C3 electrode is controlled by charge transfer in high-concentration ethanol. With the concentration of ethanol decreased, a diffusion control mechanism is observed on Ni/NiO-C3 electrode. The attenuation rate of current density is only 0.1% after 3600 s by chronoamperometry in 0.1 M ethanol aqueous solution, indicating that the Ni/NiO-C3 electrode has a superior stability. Moreover, Ni/NiO-C3 electrode exhibits an rapid current response in 0.1 mM ethanol solution and a linear relationship between 0.69 and 40.17 mM, which provides a new idea for the research of fuel cell type ethanol sensor.