Promoting charge separation in dual defect mediated Z-scheme MoS2/g-C3N4 photocatalysts for enhanced photocatalytic degradation activity: synergistic effect insight

Abstract The dual defect mediated Z-scheme MoS2/g-C3N4 photocatalyst was fabricated via a simple ultrasonic dispersion and annealing method. The structural, optical and electronic property was systematically characterized. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the MoS2 was anchored on the g-C3N4 through strong interface electrostatic interaction, which led to the formation of built-in electric field at the contact interface. The optimized MoS2/g-C3N4 heterojunction achieved a superior photoefficiency towards bisphenol A (BPA) degradation and exhibited the reaction rate normalized to specific surface area of 3.22 × 10−4 g·min−1 m−2, approximately 10.0 and 6.7 times larger than these of g-C3N4 and MoS2, respectively. The origin of the enhanced photocatalytic activity of MoS2/g-C3N4 was attributed to the formation of intimate Z-scheme surface heterostructure between MoS2 and g-C3N4, thus improved the light-harvesting ability, facilitated fast charge separation and created more active sites. The impact of anionic towards degradation efficiency was investigated. The degradation activity and degree of BPA were investigated by three-dimensional excitation-emission matrix (3D EEM) fluorescence technique. The Z-scheme charge transfer mechanism and the significant contribution of holes (h+) and superoxide radicals ( O2−) were demonstrated by electron spinning resonance (EPR), radical scavenger experiment and spectral quantification technology. This work could offer a new protocol for the design of highly efficient heterostructure photocatalysts towards environmental remediation.