Beads‐on‐string hierarchical structured electrocatalysts for efficient oxygen reduction reaction

• Published in: Carbon energy 2023-02, Vol.5 (2), p.n/a
• Main Authors: Yuan, Yang, Zhang, Qing, Li, Yinling, Lv, Luyao, Hou, Yan, Li, Ge, Fu, Jing, Yang, Lin, Bai, Zhengyu
• Format: Article
• Language: English
• Subjects: Ammonia; Beads; beads‐on‐string structure; Carbon; Catalysts; Chemical reduction; Cobalt; Crystals; Electrocatalysis; electrocatalyst; Electrocatalysts; Electrochemistry; Electrodes; Electrolytes; Electron transfer; Fuel cells; Fuel technology; Immunological tolerance; metal–organic framework; Microscopy; Nanocrystals; Nanoparticles; Nanowires; Oxygen; oxygen reduction reaction; Oxygen reduction reactions; Pyrolysis; Quantum dots; Silver; Strings
• ISSN: 2637-9368; 2637-9368
• DOI: 10.1002/cey2.253

Rational design of hierarchically structured electrocatalysts is particularly important for electrocatalytic oxygen reduction reaction (ORR). Here, ZIF‐67 crystals are stringed on core–shell Ag@C nanocables using a coordination‐modulated process. Upon pyrolysis, Ag@C strings of Co nanoparticles embedded with three‐dimensional porous carbon with beads‐on‐string hierarchical structures are developed. Due to the advantages of the rich electrochemical active sites of Co‐based “beads” and the efficient electron transfer pathways via Ag@C “strings,” the resultant NH3–Ag@C@Co–N–C‐700 catalyst shows an improved electrocatalytic activity toward ORR. NH3–Ag@C@Co–N–C‐700 shows a high onset potential of 0.99 V versus RHE, a high half‐wave potential of 0.88 V versus RHE, and a large limiting current of 5.8 mA cm−2, which are better than those of commercial Pt/C electrocatalysts. Additionally, the NH3–Ag@C@Co–N–C‐700 catalyst shows high stability and preeminent methanol tolerance, which makes NH3–Ag@C@Co–N–C‐700 a promising catalyst for oxygen electrocatalysis in fuel cell applications. In this study, we construct a “beads‐on‐string” hierarchical electrocatalyst by string‐dispersing ZIF‐67 nanoparticles with Ag@C nanowires and subsequent pyrolysis. Owing to the rich electrochemical active sites of Co‐based “beads” and the efficient electron transfer pathways via Ag@C “strings”, our catalyst exhibits superior oxygen reduction reaction performance among Co‐based catalysts.