Prominent dual Z-scheme mechanism on phase junction WO3/CdS for enhanced visible-light-responsive photocatalytic performance on imidacloprid degradation

Abstract

• The dual Z-scheme photocatalysts with phase junction WO 3 and CdS were fabricated. • The 75CW has the best photocatalytic rate of imidacloprid degradation. • The Fukui indexes were exploited to predict reactive sites. • The reliable degradation pathways of imidacloprid were proposed. The construction of dual Z-scheme photocatalysts is an effective way to promote the separation and migration of electrons-holes as well as retain their high redox abilities. Herein, a distinctive dual Z-scheme photocatalyst based on phase junction WO 3 and CdS (CW) was successfully fabricated via hydrothermal method and in-situ precipitation process. The as-prepared materials showed the advantages of both phase junction and dual Z-scheme mechanism (promoted utilization of carriers and improved redox potential). As a result, the k app value of 75CW (0.05237 min −1 ) was 29.8 times that of phase junction WO 3 (0.00176 min −1 ) and 2.9 times that of CdS (0.01799 min −1 ) in terms of imidacloprid (IMD) degradation. Trapping experiment and electron spin resonance (ESR) proved the dual Z-scheme mechanism, the key to significantly improve photocatalytic degradation efficiency of WO 3 /CdS nanocomposites. Combined the analysis of liquid chromatography-mass spectrometry (LC-MS) with density functional theory (DFT) calculation, rational degradation pathways of IMD were put forward in detail. This work is excepted to provide new horizons for the construction of dual Z-scheme system with phase junction and the photodegradation of IMD.