Hu Jinsong, Institute of chemistry, Chinese Academy of Sciences, has made new progress in the research of universal macro preparation of high loading monoatomic dispersed metal nitrogen catalyst

In recent years, monoatomic catalysts have become the research frontier and hotspot because of their high atom utilization, clear catalytic activity center and high catalytic performance However, due to the easy migration and aggregation of active atoms in the preparation process, there are still great challenges in the controllable preparation of monoatomic catalysts How to realize the high-density active sites and how to realize the low-cost macro preparation are the key to the application of monoatomic dispersion catalysts Metal nitrogen catalysts are widely used in fuel cell, zinc air cell, electrolytic water and other electrochemical energy devices, but their formation usually requires high temperature, metal atoms are easier to agglomerate, so it is more challenging to prepare high-density, single atom dispersed metal nitrogen (m-nx) catalysts With the support of NSFC, the Ministry of science and technology and the Chinese Academy of Sciences, Hu Jinsong research group, Key Laboratory of molecular nanostructure and nanotechnology, Institute of chemistry, Chinese Academy of Sciences, is committed to the design, controllable construction and catalytic mechanism research of high-performance non noble metal electrocatalysts In recent years, they have been discussing metal nitrogen oxygen reduction electrocatalysts (j.am.chem.soc 2016, 138, 3570; ACS catalyst 2015, 5, 2903; ACS appl Mater Interfaces 2015, 7, 11508; 2017, 9, 5272; carbon 2016, 107, 162; j.mater Chem A 2016, 4, 7781; chem Commin 2018, 54, 8190; appl Catalyst B environ 2019, 251, 240, etc.) and monoatom dispersed fe-n-c electrocatalyst (chem Commun 2018, 54, Based on the research of 1307), a new simple strategy of cascade anchoring was developed The universal macro synthesis of monoatomic dispersed metal nitrogen catalyst with metal loading up to 12% was realized The catalyst showed excellent and stable electrocatalytic performance The related work was published in NAT Commun (DOI: 10.1038 / s41467-019-09290-y) In order to obtain high loading monoatomic dispersed metal nitrogen sites, the researchers use 1) complexing agents (such as cheap glucose, etc.) to form complexes with metal ions to physically isolate metal sources at the atomic scale; 2) The three-dimensional porous carbon carrier with high specific surface area, rich oxygen functional groups on the surface and high-speed mass transfer and load transfer characteristics is used to realize the high-density loading of metal complexes on the surface of the carrier; 3) the physical separation of metal complexes on the molecular scale by using excessive complexing agents; 4) the nitrogen-containing precursor (such as melamine, etc.) during high-temperature pyrolysis ）The CNx fragment formed by in-situ decomposition can form m-nx structure with the metal atom decomposed by the complex, and form porous carbon network with the carbon produced by decomposition on the surface of the carrier, thus anchoring m-nx in situ and exposing it as an effective catalytic site In the experiment, high-density and stable monoatom dispersed m-nx catalyst can be obtained by mixing glucose solution with porous carbon carrier and metal salt precursor and heat treatment with melamine This strategy is suitable for many kinds of metals, carriers and complexing agents; the preparation process is simple, the cost is low, and the catalyst can be prepared on a large scale; the performance of the catalyst is excellent For example, the half wave potential of alkaline oxygen reduction of Fe NX catalyst can reach 0.90 V, and the kinetic mass activity can reach 100.7 A / g at this potential, which is significantly better than that of commercial 20 wt% Pt / C catalyst; the Faraday efficiency of Ni NX catalyst can also reach 89% at a current density of 30 MA / cm 2 for the reduction of CO 2 This new step-by-step anchoring strategy provides a new universal method for the preparation of monoatomic dispersed m-nx catalysts with high density, high activity and high stability