Synthesis of nitrogen-doped ordered mesoporous carbon electrocatalyst: Nanoconfinement effect in SBA-15 template

Abstract

The effect of the pore structure of SBA-15, which is tuned by varying the hydrothermal temperature (90–150 °C), is investigated on nitrogen-doped ordered mesoporous carbon. It is found that the pore structure of SBA-15 yields effects on both the composition and the pore structure of carbon, which thereby affecting its electrocatalytic activity for the oxygen reduction reaction (ORR). XPS reveals that the nitrogen content of the template-free carbon is 2.79 at.%, while dramatically increases to 4.48, 5.01 and 4.16 at.% for the three template-aided carbon catalysts with SBA-15 synthesized at 90, 130 and 150 °C, respectively. Nitrogen ad/desorption isotherms show that the specific surface area of the template-free carbon is 257 m2 g−1, which increases to 724, 731 and 691 m2 g−1 for the above three carbons. Such changes correlate well with the electrochemical results. RRDE results show that the template-aided carbon catalysts yield better activity and selectivity for the ORR than does the template-free one. And the best performance is achieved for the carbon catalyst with SBA-15 synthesized at 130 °C, which coincidentally has the highest nitrogen content and surface area.