Last modified: 2014-10-20
Abstract
Non precious metal (NPM) catalysts, which are much cheaper, have been reported as promising candidates of replacing Pt for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. However, the activity and stability of NPM catalysts can’t match that of Pt catalyst. Different approaches of synthesis need to be employed to improve the electrochemical performance of NPM catalysts.
The high surface area, high porosity and proper pore structure of catalyst usually lead to high catalytic activity for ORR. In this paper, we choose templating method to synthetize polyporous NPM catalysts. Nanoscale SiO2 was employed as sacrificial supports to create pores. The M-PEI (metal/PEI=1:3, M=Fe, Co, Ce) catalysts were prepared by homogeneously dispersed metal and poly(ethyleneimine) precursors onto the surface of SiO2(the metal loading with respect to silica is 15.wt%). Then, SiO2 was etched by 40.wt% HF after pyrolysis in an N2 atmosphere at 800oC for 1h. The pore with size consisted with the diameter of SiO2 formed in the position where SiO2 occupied before. Base on this method, we prepared M-PEI catalyst with high surface area. The kinetics and electrocatalytic activity on the M-PEI catalysts have been measured using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating disk electrode (RDE). All these tests were carried out in 0.1M KOH at the ambient solution temperature.
Figure 1 displays the CVs of Fe-PEI, Co-PEI and Ce-PEI catalysts. The result clearly revealed that the peak potentials of Co-PEI and Fe-PEI catalysts were higher than that of Ce-PEI, reached 0.391mA, respectively.
Figure 2 shows the polarization curves of the three electrodes. The result shows that the Co-PEI had high electroactivity for the ORR. The onset potential of Co-PEI was similar to that of Fe-PEI and higher than that of Ce-PEI, while the half-wave potential of Co-PEI was higher than that of both the other two. The onset potential and half-wave potential of Co-PEI catalysts are about 0.72 and 0.38 V.
Non precious metal (NPM) catalysts, which are much cheaper, have been reported as promising candidates of replacing Pt for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. However, the activity and stability of NPM catalysts can’t match that of Pt catalyst. Different approaches of synthesis need to be employed to improve the electrochemical performance of NPM catalysts.
The high surface area, high porosity and proper pore structure of catalyst usually lead to high catalytic activity for ORR. In this paper, we choose templating method to synthetize polyporous NPM catalysts. Nanoscale SiO2 was employed as sacrificial supports to create pores. The M-PEI (metal/PEI=1:3, M=Fe, Co, Ce) catalysts were prepared by homogeneously dispersed metal and poly(ethyleneimine) precursors onto the surface of SiO2(the metal loading with respect to silica is 15.wt%). Then, SiO2 was etched by 40.wt% HF after pyrolysis in an N2 atmosphere at 800oC for 1h. The pore with size consisted with the diameter of SiO2 formed in the position where SiO2 occupied before. Base on this method, we prepared M-PEI catalyst with high surface area. The kinetics and electrocatalytic activity on the M-PEI catalysts have been measured using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating disk electrode (RDE). All these tests were carried out in 0.1M KOH at the ambient solution temperature.
Figure 1 displays the CVs of Fe-PEI, Co-PEI and Ce-PEI catalysts. The result clearly revealed that the peak potentials of Co-PEI and Fe-PEI catalysts were higher than that of Ce-PEI, reached 0.391mA, respectively.
Non precious metal (NPM) catalysts, which are much cheaper, have been reported as promising candidates of replacing Pt for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. However, the activity and stability of NPM catalysts can’t match that of Pt catalyst. Different approaches of synthesis need to be employed to improve the electrochemical performance of NPM catalysts.
The high surface area, high porosity and proper pore structure of catalyst usually lead to high catalytic activity for ORR. In this paper, we choose templating method to synthetize polyporous NPM catalysts. Nanoscale SiO2 was employed as sacrificial supports to create pores. The M-PEI (metal/PEI=1:3, M=Fe, Co, Ce) catalysts were prepared by homogeneously dispersed metal and poly(ethyleneimine) precursors onto the surface of SiO2(the metal loading with respect to silica is 15.wt%). Then, SiO2 was etched by 40.wt% HF after pyrolysis in an N2 atmosphere at 800oC for 1h. The pore with size consisted with the diameter of SiO2 formed in the position where SiO2 occupied before. Base on this method, we prepared M-PEI catalyst with high surface area. The kinetics and electrocatalytic activity on the M-PEI catalysts have been measured using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating disk electrode (RDE). All these tests were carried out in 0.1M KOH at the ambient solution temperature.
Figure 1 displays the CVs of Fe-PEI, Co-PEI and Ce-PEI catalysts. The result clearly revealed that the peak potentials of Co-PEI and Fe-PEI catalysts were higher than that of Ce-PEI, reached 0.391mA, respectively.