Phase diagrams guide synthesis of highly ordered intermetallic electrocatalysts: separating alloying and ordering stages

• Published in: Nature communications Vol. 13; no. 1; pp. 7654 - 8
• Main Authors: Zeng, Wei-Jie, Wang, Chang, Yan, Qiang-Qiang, Yin, Peng, Tong, Lei, Liang, Hai-Wei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.12.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/299/893; 639/301/357/354; 639/638/77/886; Alloying; Alloys; Annealing; Catalysts; Chemical reduction; Chemical synthesis; Durability; Electrocatalysts; Evolution; Fuel cells; Fuel technology; High temperature; Humanities and Social Sciences; Intermetallic compounds; Low temperature; multidisciplinary; Oxygen reduction reactions; Phase diagrams; Proton exchange membrane fuel cells; Science; Science (multidisciplinary); Temperature dependence; Transition temperature; X-ray diffraction
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-35457-1

Supported platinum intermetallic compound catalysts have attracted considerable attention owing to their remarkable activities and durability for the oxygen reduction reaction in proton-exchange membrane fuel cells. However, the synthesis of highly ordered intermetallic compound catalysts remains a challenge owing to the limited understanding of their formation mechanism under high-temperature conditions. In this study, we perform in-situ high-temperature X-ray diffraction studies to investigate the structural evolution in the impregnation synthesis of carbon-supported intermetallic catalysts. We identify the phase-transition-temperature ( T PT )-dependent evolution process that involve concurrent (for alloys with high T PT ) or separate (for alloys with low T PT ) alloying/ordering stages. Accordingly, we realize the synthesis of highly ordered intermetallic catalysts by adopting a separate annealing protocol with a high-temperature alloying stage and a low-temperature ordering stage, which display a high mass activity of 0.96 A mg Pt –1 at 0.9 V in H 2 –O 2 fuel cells and a remarkable durability. The synthesis of highly ordered intermetallic compound catalysts remains a challenge owing to the limited understanding of their formation mechanism under high-temperature conditions. Here the authors identify phase-transition-temperature-dependent evolution process in the synthesis of intermetallic Pt catalysts and propose a separate alloying/ordering annealing synthetic protocol.