Mesoporous carbon nitride synthesized by nanocasting with urea/formaldehyde and metal-free catalytic oxidation of cyclic olefins

Mesostructured carbon nitride has been synthesized by nanocasting method with urea/formaldehyde as carbon and nitrogen sources by using disk-shaped 2D hexagonal mesoporous silica (INC-2) as a hard template. The resulted mesoporous carbon nitride (UF-MCN) was characterized as a graphitic structure with hexagonal pores of 3–4 nm and short channels in the submicron range. The catalytic oxidation ability of UF-MCN was demonstrated in the metal-free oxidation of cyclic olefins with hydrogen peroxide. The conversions for cyclopentene, cyclohexene and cis-cyclooctene were obtained in the range of 65–80% and selectivities onto epoxides were 40–90%, respectively. The UF-MCN could illustrate the considerable catalytic oxidation activities due to the existence of surface oxygen species.

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► UF-MCNs (urea–formaldehyde mesoporous carbon nitrides) were synthesized by nanocasting of urea/formaldehyde as N, C source over INC-2 as hard template.
► The obtained disk shaped UF-MCN was replica of INC-2.
► The existences of surface oxygen species were confirmed by XPS measurements which are presumed to be catalytic active sites for oxidation.
► The UF-MCN-1.0 showed catalytic performance in oxidation of cyclic olefins with 80% conversion of cyclooctene and 92% selectivity of cyclooctene oxide.