Effect of N content in g-C3N4 as metal-free catalyst on H2O2 decomposition for MB degradation
By Wang, Xunhe; Li, Dongqi; Nan, Zhaodong
Published in Separation and Purification Technology
2019
Abstract
Graphitic carbon nitrides (g-C3N4) were fabricated with different N contents through a convenient method, where C3.00N4.67 (named as CN-S) and C3.00N4.72 (named as CN-N) were obtained. Compared with metal-containing catalysts, CN-S and CN-N were more suitable for activating H2O2 to decompose methylene blue (MB) in the presence or absence of visible light. Effects of the amounts of MB, catalyst and H2O2, and pH of the solution on the MB decomposition were investigated. The results revealed that the conversion of CC bonds to CN bonds improved the transfer of photo-generated electrons and holes, the more positive valence bands, and the C vacancy. These special properties enhanced the catalytic activity for CN-N. The rate constant for CN-N was 0.0508 min−1 under irradiation, which was about 8.7 times than CN-S (0.00585 min−1). The degradation efficiency under light was increased about 1.7 times than that without light for the CN-N and CN-S. Different catalytic mechanisms with and without irradiation were proposed. Simultaneously, CN-N showed the highest catalytic activity at neutral pH values and high stability for many cycles application, which demonstrated that CN-N can be conveniently applied for environment treatment.