Atomically dispersed Co–N–C electrocatalysts synthesized by a low-speed ball milling method for proton exchange membrane fuel cells

Abstract

Atomically dispersed cobalt–nitrogen–carbon (Co–N–C) catalysts have appeared as potential substitutes to costly noble-metal catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). After carrying out research for a period of time, great progress has been made in preparing atomically dispersed catalysts by pyrolysis of the ZIF-8 precursor. However, the current synthesis method has many disadvantages, such as low reaction conversion, pollution and high cost. To overcome these shortcomings, a low-speed ball milling method was applied to synthesize the precursor of Co–N–C catalysts. The conversion efficiency of the precursor and metal doping rate were greatly improved by ball milling in a micro-solvent environment. Moreover, the environmentally friendly synthesis process does not involve a large amount of organic solvent and metal ions. In addition to the detailed characterization of the single-atom properties of the catalyst by the X-ray absorption fine structure and other means, and a thorough electrochemical characterization demonstrates its ORR capacities (E_1/2 = 0.78 V) in acidic media. The test of PEMFCs proved a promising maximum power density (450 mW cm⁻²) and long-term stability. This work provides a new method and idea for the efficient and green synthesis of high-performance catalysts for commercial application of PEMFCs.