China University of Science and Technology has made new progress in intermetallic compound fuel cell catalysts

Recently, Professor Liang Haiwei's research group at the University of Science and Technology of China developed a small molecular-assisted impregnation method to achieve the universal preparation of carbon supported small size platinum intergeneric compound (Pt-IMC) fuel cell catalyst, and the prepared catalyst showed excellent low platinum fuel cell performance. The research results are entitled "Small molecule-assisted synthesis of carbon supported platinum intermetallic fuel cell catalysts". Published in the international journal Nature Communications.

Pt-IMC catalysts with ordered atoms have higher activity and stability than traditional disordered solid solution alloys in cathode oxygen reduction reaction (ORR) of PEMFC. However, the synthesis of PT-IMC catalysts usually requires high temperature annealing to overcome the energy barrier of atomic migration ordering, resulting in sintering of particles and reduced utilization of Pt. Therefore, developing the synthesis method of Pt-IMC catalyst with small particle size and high order is the key to improve the performance of PEMFC and reduce the cost. In October last year, Liang Haiwei's research group and collaborators developed a method of high-temperature sulfur anchoring to achieve the universal synthesis of Pt-IMC catalysts (Science 2021, 374, 459-464). Recently, the research group has made new progress in this field: using small molecule assisted impregnation method and direct use of commercial carbon black carrier, the synthesis of gram grade Pt-IMC fuel cell catalyst has taken an important step towards the practical application of this kind of catalyst.

In this work, the researchers developed a small-molecule-assisted synthesis strategy of small-sized Pt-IMC catalysts, using small molecules containing heteroatomic (O, N, S) functional groups as additives in the impregnation process, which has a significant effect on particle sintering inhibition compared to the direct impregnation method. In particular, when small molecules containing mercaptoyl, such as sodium thioglycolate, were annealed at 700℃, X-ray diffraction test results showed that the average particle size of the synthesized PtCo particles was only 2.5 nm, much smaller than the particle size of 14.9 nm without small molecules (FIG. 1). In addition, small molecular additives containing O and N heteroatoms also have a certain effect of inhibiting high temperature sintering of catalysts.

Figure 1. Extensive screening of a range of small molecule additives containing different heteroatoms (O, N, S). Small molecule additives containing sulfhydryl group show excellent high temperature resistance to sintering.

图2. Pt-Construction of IMC material library: 18 binary Pt-IMC catalysts.

图3. PtCo-IMC催化剂的氧还Primary activity and fuel cell performance testing.

Article link:https://doi.org/10.1038/s41467-022-34037-7

(School of Chemistry and Materials Science, National Research Center for Microscale Matter Science, Department of Scientific Research)