The research group of Professor Wang Zhenbo of Harbin University of technology has made important progress in the study of the evolution of non noble metal catalyst active center of fuel cell

Recently, Professor Wang Zhenbo from the school of chemical engineering and chemistry of Harbin University of technology and Professor Wu Gang from the University of buffalo, New York, cooperated with zif-8 nitrogen doped carbon (zif-nc) after high-temperature carbonization as the matrix to prepare fe-n-c catalyst with atom level dispersed activity center of fen4 through Fe3 + adsorption and thermal activation process With the help of this model system, high performance was studied and revealed The formation mechanism of the active center of fen4 in the process of thermal activation The research and preparation of high-performance and low-cost non noble metal oxygen reduction catalyst is the key to realize the commercial application of PEMFC Fe-n-c Co doped with n is the most active non noble metal catalyst at present, and the coordination structure of fen4 is considered to be the main active center However, the formation mechanism of high-performance fen4 active center is not clear, because the existing catalysts are all prepared by the precursor composed of high-temperature pyrolysis transition metal salt, nitrogen source and carbon source, and the evolution process of Fe NX structure occurs simultaneously with the high-temperature carbonization process and nitrogen doping process Exploring and studying the formation mechanism of the active center of fen4 is helpful to the reasonable design and further improvement of the performance of fe-n-c catalyst Firstly, the team confirmed the effectiveness of the above model system by means of physical characterization such as transmission electron microscopy (TEM), Raman, N2 desorption test, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) - the morphology, structure of carbon matrix and nitrogen doping did not change significantly during the thermal activation process Then, the dispersive state and structure evolution of Fe species in the process of thermal activation were characterized and analyzed by means of scanning transmission electron microscopy (stem) and X-ray absorption spectroscopy (XAS) The performance evolution of catalyst was tested by means of rotating disc ring electrode and fuel cell, and the structure of catalyst in the process of thermal activation was established- The first principle of performance evolution is studied In addition, the model system for the first time realizes the regulation of the density of the active center of fen4 without changing the pore structure of carbon matrix and nitrogen doping, which provides a good platform for other related theoretical research After the optimization of carbon matrix structure and Fe3 + adsorption capacity, the half wave potential of the catalyst for orr in H2SO4 was as high as 0.84 V (vs rhe, 0.6 mg / cm 2), and the current density at 0.9 V in fuel cell test was as high as 30 MA / cm2 (US Department of energy target 44 MA / cm2) The results were published in angew Chem Int ed (DOI: 10.1002 / anie 201909312) The first author of the paper was Li Jiazhan, a doctoral candidate from Harbin University of technology, and Harbin University of technology was the first communication unit of the paper.