The reporter learned from the Institute of Process Engineering of the Chinese Academy of Sciences that Wang Dan's team, a researcher at the State Key Laboratory of Biochemical Engineering, has developed a sp hybrid nitrogen-doped graphyne, which has been shown to catalyze the cathode oxygen reduction (ORR) of fuel cells Good catalytic performance. The research results were recently published in Nature-Chemistry.
Fuel cell is a device that converts chemical energy into electrical energy. It has the advantages of zero pollution, high energy conversion efficiency, and wide application range. It is one of the most promising new energy conversion devices. The cathodic oxygen reduction reaction (ORR) is a kinetically slow process that requires the action of a catalyst to output an effective current density.
Dan Wang told the China Science News reporter that traditional ORR catalysts are mainly expensive platinum-based materials, and the development of inexpensive non-precious metal ORR catalysts is an inevitable choice to promote the scale application of fuel cells.
Studies have confirmed that nitrogen-doped carbon-based catalysts have good ORR catalytic activity and stability and are expected to replace platinum-based catalysts in fuel cell applications. The nitrogen-doped configuration has many different forms, including pyridine nitrogen, imine nitrogen, pyrrole nitrogen, amino nitrogen, nitrile nitrogen, graphite nitrogen, and nitrogen oxide. "Researchers generally believe that the presence of pyridine nitrogen creates an ORR active site, while other high-performance nitrogen-doped configurations are rarely reported." Wang Dan said.
Based on thin-layer graphene alkyne materials, researchers successfully introduced a new type of sp hybrid nitrogen atom on the alkyne bond of thin-layer graphene alkyne through a pericyclic reaction to achieve fixed-point and quantitative doping of nitrogen. According to reports, compared with other forms of nitrogen configuration, the introduction of sp hybrid nitrogen atoms makes the surrounding carbon atoms have more positive charges, which is more conducive to the adsorption and activation of oxygen, and makes it easier for electrons to transfer to the catalyst surface. Significantly improve the catalytic performance of ORR.
Experimental results show that the material has a half-wave potential of 0.87 volts and a dynamic current density of 38 milliamps per cubic centimeter under alkaline conditions. This data is better than commercial platinum-carbon catalysts and shows better stability. And methanol tolerance. Under acidic conditions, although the activity of this material is slightly lower than commercial platinum-carbon catalysts, it is still superior to other non-metallic catalysts.
The paper states that the mechanism and strategy of controllable doping of nitrogen atoms provides a new idea for the design of catalysts, which strongly promotes the process of replacing platinum-based catalysts with non-metal catalysts.