Study on the Preparation of Oxygen Reduction Catalyst for Fuel Cell by NH3 Heat Treatment ZIF-8

Abstract

The development of catalyst in fuel cell is seriously hampered due to high preparation costs and complex processes. In this paper, a graded porous N-doped carbon material was prepared using NH3 heat treatment ZIF-8, and its microstructure and electrochemical behavior. were characterized and analyzed. It is found that the chemical etching process can introduce mesoporous (2-50nm) or macropores (>50nm) into ZIF-8 to form. a graded porous structure, and the pore size of ZIF-8 can be effectively adjusted by controlling the pH of the etching solution. The NH3 heat treatment can effectively adjust the pore structure in carbon materials, increase the number of micropores (<2nm) and mesopores in the materials, and increase the specific surface area of the materials. NH3 can be used as an N source to dope the material with a certain amount of N. It can also regulate the conversion of pyridine N and pyrrole N in the carbon material to the more stable graphite N, and the pore structure and N doping content of the carbon material can be reasonably controlled by controlling the temperature of NH3 heat treatment. The N-C@2. 5pH-1000 prepared in this paper has excellent electrocatalytic performance, similar oxygen reduction reaction (ORR) activity and better cycling stability than commercial Pt/C catalysts. The synthetic strategy proposed in this paper provides a new idea for the preparation of efficient and inexpensive fuel cell catalysts.