Synthesis of Co-loaded carbon aerogels for oxygen electro-reduction

Melamine-resorcinol-formaldehyde( MR) aerogels were prepared by the sol-gel polymerization of formaldehyde with melamine and resorcinol using NaOH as catalyst,follow ed by freeze-drying.Co-loaded carbon aerogels w ere obtained by impregnating the MR aerogels w ith Co( III) tert-butanol solution,follow ed by carbonization in N 2.The effects of the molar ratios of melamine to resorcinol( M/R),pH,Co content and carbonization temperature on the microstructure of the aerogels w ere investigated.It w as found that the microstructure of the MR aerogels could be adjusted by the M/R ratio and pH.The mesopore size of the MR aerogels decreased w ith increasing pH and the mesopore size w as in the range of 3-4nm w hen the M/R w as 6∶ 1.There w ere some graphitic nano-ribbons in Co-loaded carbon aerogels.The metal average particle size in the carbon aerogels increased from 5.2 to 6.2 nm w hen the carbonization temperature w as increased from 700 to 900 ℃.The electrochemical properties of the Co-loaded carbon aerogels as catalysts in the oxygen reduction reaction w ere evaluated by a rotating disc electrode technique in an O 2-saturated 0.5 mol/L H 2 SO 4 solution,and the catalysts show ed a good electrocatalytic activity for the reaction.