Mesoporous graphitic carbon nitride functionalized iron oxides for promoting phenol oxidation activity

Abstract

Mesoporous graphitic carbon nitride was found to be a superior support of iron oxides, improving the dispersion, adjusting the iron oxidation state, and promoting the catalytic oxidation of phenol. The physicochemical characteristics of the as-prepared FeO_x/g-C₃N₄ were evaluated by XRD, FT-IR, TEM, N₂ sorption and XPS, which together revealed the influence of the g-C₃N₄ support on the physicochemical properties of FeO_x. The catalytic activity was evaluated by phenol oxidation reaction under ambient condition. Importantly, FeO_x are highly dispersed and due to the large S_BET and the support's amino group's adjusting the crystallization process of Fe(III). The carbon nitride supported catalyst attained 80% conversion in 30 minutes for phenol oxidation under equivalent conditions to which a SBA-15 supported Fe catalyst only achieved 3% conversion within 60 minutes. We speculate that the partial pyrolysis of g-C₃N₄ leads to the formation of carbon and nitride fragments that alter the redox properties during the formation of FeO_x, therefore, producing more Fe(II) species, which contributes to enhanced Fenton activity. The strategy of using mesoporous g-C₃N₄ as a support is a reliable method for preparing highly dispersed transition metal oxides with adjustable physicochemical state.