Co₃O₄/carbon Nanotubes Nanocomposites And Its Electrocatalytic Properties

Energy is the key issue closely related to human survival and development. In recent years, the fuel cells develop rapidly. But the current bottleneck for fuel cells is the sluggish oxygen reduction reaction on the cathode side. Despite tremendous efforts, developing a highly efficient ORR catalyst at low-cost, high-performance, low-pollution is a great challenge. Here, we have synthesized core-shell Co@Co3O4 nanoparticles embedded in the bamboo-like N-doped carbon tubes and Co3O4/CNT by a simple heat treatment. Then we can control the oxidation of Co embedded in BNCNTs and N content to adjust their catalytic performance of oxygen reduction reaction. When oxidized at 300 ?, the catalytic activity of synthetic Co@Co3O4/BNCNTs-300 complex was the largest for the oxygen reduction reaction. Compared with the Co3O4/CNT catalyst the synthetic Co@Co3O4/BNCNTs-300 catalyst also exhibits a higher ORR catalytic activity. Even the cycle stability is higher than that of the highly efficient Pt/C catalyst. The tolerance for methanol molecules of the catalyst is superior to that of the Pt/C catalyst. The ORR catalytic activity of the Co3O4/CNTs catalyst is higher than Co/BNCNTs, Co@Co3O4/BNCNTs-250 and Co@Co3O4/BNCNTs-350 catalyst, because the Co3O4 nanoparticles of the Co3O4/CNTs catalysts have a bigger catalyst activity area. In short, the reason why the core-shell Co@Co3O4 nanoparticles embedded in the bamboo-like N-doped carbon tubes are so efficient are mainly due to:(1) There are many core-shell Co@Co3O4 nanoparticles which are embedded in BNCNTs. The reason why the Co@Co3O4/BNCNTs has a good ORR catalytic activity is due to the improved electrical conductivity of the cobalt oxide. And the reactive sites of the Co@Co3O4/BNCNTs catalyst are considered to be on the Co3O4 rather than on cobalt nanoparticles. The oxides on the carbon matrices can enhance the electronic transmission rate and improve the catalytic activity of the ORR.(2) The N-doping in BNCNTs. N doping enhances the performance of the catalytic activity. N-doping structure in carbon layer and the formation of the Co3O4 on Co surface collaboratively promote the catalyst activity of the oxygen reduction.