Facile synthesis of carbon-rich g-C3N4 by copolymerization of urea and tetracyanoethylene for photocatalytic degradation of Orange II

Abstract

A novel graphitic carbon nitride (g-C3N4) photocatalyst was synthesized by a facile one-pot thermo-induced copolymerization method using urea and tetracyanoethylene (TCNE) for the first time. It was revealed that the as-prepared samples retained the original framework of g-C3N4, showed an increased surface area and enhanced visible-light harvesting, and promoted photoexcited charge carrier separation. The photocatalytic efficiency of the samples was investigated by degradation of Orange II solutions under visible-light irradiation (λ > 420 nm). The sample CN/TCNE-40 (40 mg TCNE in 30 g urea) achieved an Orange II degradation rate of about 91% in 60 min under visible-light irradiation, which is significantly higher than that of pristine g-C3N4 (51%). The pseudo-first-order rate constant for Orange II degradation on CN/TCNE-40 was 0.0317 min−1, 4.88 times as large as that of pristine g-C3N4. The CN/TCNE-40 sample maintained its high photoactivity after five cycles under identical experimental conditions and could degrade Orange II at various pH conditions under visible-light irradiation, confirming the high durability of the photocatalyst. The mechanism of the enhanced photocatalytic performance was also discussed. The results suggested that the CN/TCNE samples are potential photocatalysts for environmental and energy applications.