Fabrication of mediator-free g-C3N4/Bi2WO6 Z-scheme with enhanced photocatalytic reduction dechlorination performance of 2,4-DCP

Abstract Chlorophenols (CPs) have been considered as a kind of priority environmental pollutants for their potential detrimental effects, and photocatalytic reduction dechlorination tend to be a promising approach to CPs’ removal. In this work, 2,4-dichlorophenol (2,4-DCP) was adopted as the model pollutant of CPs, and a simple mixing and heating method was employed to prepare graphitic carbon nitride and bismuth tungstate (g-C3N4/Bi2WO6) binary photocatalysts. Under UV–vis light irradiation and anoxic atmosphere, the g-C3N4/Bi2WO6 samples exhibited enhanced photocatalytic activities. The optimal dechlorination rate constant of 2,4-DCP over g-C3N4/Bi2WO6 (weight ratio 3:7) was 1.13 h−1, 7.6 and 8.9 times higher than that of pristine g-C3N4 and Bi2WO6 respectively. The enhanced activities originated from the effective suppression of charge recombination and extended spectrum absorption range. Kinetic studies revealed that the dechlorination processes followed the pseudo-first-order model. The photocatalytic mechanism of 2,4-DCP over g-C3N4/Bi2WO6 was discussed in detail, and based on which, a mediator-free Z-scheme mechanism was proposed. This work extends the application range of g-C3N4/Bi2WO6 photocatalyst and provides a new insight into environmental remediation.