3D honeycomb-like ordered porous structure supports Pt single-atom electrocatalysts

Study on Pt single-atom catalysts supported by 3D honeycomb-like ordered porous structures and their ORR electrocatalytic properties

Recently, yan Changfeng, a researcher at the Guangzhou Institute of Energy Research of the Chinese Academy of Sciences, and the Institute of Metal Research of the Chinese Academy of Sciences have made progress in developing a three-dimensional honeycomb mesoporous structure supporting Pt single-atom hydrogen fuel cell catalysts, and the relevant research results were published in the Royal Society of Chemistry (RSC) journal “Materials Chemistry Series A”. The research work is supported by the STS Key Project of the Chinese Academy of Sciences and the Guangzhou Science and Technology Plan Project.

Hydrogen fuel cells have the advantages of green and low carbon, and are an important means to cope with future challenges such as carbon neutrality and climate change. As a key process of PEMFC cathodic reaction, the efficiency of oxygen reduction reaction (ORR) determines the performance, life and cost of the battery. In the current commercially used carbon-loaded platinum (Pt/C) catalyst, the active components of Pt are mostly distributed in disorder on the surface of the carbon support, resulting in uneven distribution of active sites; and in the process of fuel cell operation, the interaction between Pt and the carrier is reduced, resulting in the shedding, migration and agglomeration of Pt components, which ultimately leads to the attenuation of the overall performance of THEPMFC.

Based on the molecular self-assembly mechanism, the researchers took the block copolymer (BCP) of the pyridine N structure as the structure guide agent, complexed the Pt precursor in situ, self-assembled with the carbon source template agent, and obtained a highly ordered three-dimensional honeycomb mesoporous structure supported Pt single atom catalyst (Pt/N-OHC) by post-processing means such as carbonization, surface modification and reduction. The results show that Pt/N-OHC, as a controllable high-dimensional mesoporous catalytic material, has both nanoscale characteristic properties such as small size effect and surface effect and long-range ordered macroscopic properties. The catalyst layer of the honeycomb structure is thinner, and the Pt active site layer is distributed at the boundary of the pore surface and the vertical pore, which is in line with Middelman’s setting of the ideal electrode catalytic layer, which is conducive to the full utilization of the active site and the transmission of heterogeneous reactants.

Further research found that the ordered porous honeycomb structure is derived from the self-assembling structural control, and the Pt-N coordination bond formed by the strong interaction between the Pt monoatomic and the honeycomb structure through the strong interaction between the metal-carrier (MSI) can not only inhibit the migration agglomeration of Pt and improve the stability of Pt, but also can be used as an active site to effectively reduce the energy barrier in the ORR reaction. At the same time, by adjusting the parameters of the BCP self-assembly process, the control of the Pt active components from single atoms to ultrafine nanoparticles (average particle size of about 2.5 nm) and the thickness control of the honeycomb structure (20 nm-60 nm) can be realized, thereby better regulating the electrocatalytic activity of ORR. (Source: China Science Daily Zhu Hanbin)

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