Institute of Solid State Physics, Chinese Academy of Sciences, Institute of Solid State Physics, Chinese Academy of Sciences, Preparation and processing of iron-nitrogen-doped porous carbon/graphene composites with dual active sites, and their application in oxygen reduction Made progress, related work was published on ACS Applied Materials & Interfaces.
Due to the depletion of fossil energy and the deterioration of the natural environment, people have begun to vigorously develop sustainable energy storage and conversion systems such as metal air batteries, fuel cells, etc. However, the oxygen reduction reaction (ORR) power of these energy conversion and storage devices The learning process is slow and often requires the use of a catalyst to increase the activity of the reaction.
Studies have found that platinum-based electrocatalysts are currently the catalysts with better performance for ORR. However, the precious metal platinum reserves are small, and the price is expensive, which is not conducive to large-scale application. Therefore, to find a non-precious metal catalyst with excellent performance and good stability. It is the direction of research. Among them, iron-nitrogen/carbon-based electrocatalysts are receiving increasing attention due to the rich metal-nitrogen dual active sites on the surface. Currently, such catalysts are usually synthesized at high temperatures. And in the synthesis process easily lead to catalyst agglomeration, thus reducing the specific surface area of the catalyst and the number of exposed active sites.
In response to these problems, researchers used liquid-phase laser ablation technology to create special local extreme conditions (liquid-solid interfaces) in a mild environment. First, they obtained ferrocolloid nanoparticles with high activity and high chemical reactivity. The Fe-NC/rGO electrocatalyst can be uniformly supported on the surface of graphene oxide (GO) nanosheets by introducing a carbon-nitrogen source and subsequent pyrolysis process (as shown in (a) to (e)). Due to the sheet-like structure formed after compounding with graphene, the catalyst agglomeration is effectively avoided, the specific surface area and exposed active sites of the catalyst are increased, and the catalytic activity of the iron-nitrogen/carbon-based electrocatalyst is further improved. Further electrochemical tests are performed. It shows that it has good electrocatalytic properties (as shown in (f)-(i)), and the Fe-based nanoparticles and Fe-N sites contained in the catalyst have important influence on the catalytic activity of the catalyst.
The research work provides new research ideas for the construction and development of new metal-nitrogen/carbon-based electrocatalysts, and is expected to replace precious metal platinum for fuel cells and metal-air batteries. The research work has obtained the national key basic research development plan (973 Program), National Natural Science Foundation of China, Research Facility Development Project of the Chinese Academy of Sciences, etc.
Fe-NC/rGO catalysts: (a) SEM photographs; (b, c) TEM photographs; (d) HAADF-STEM photographs; (e) EDX mapping photographs; (f) Different catalysts in 0.1 M nitrogen or oxygen saturated KOH Cyclic voltammograms of the solution; (g) Linear sweep voltammetry curves of Fe-NC/rGO in oxygen-saturated 0.1 M KOH solution; (h) Difference of Fe-NC/rGO in 0.1 M KOH solution saturated with oxygen Linear sweep voltammograms at speed; (i) Comparison of Tafel curves for different catalysts.
