Abstract
Heterostructured photocatalysts have demonstrated great potential in the photodegradation of organic pollutants, while the surfaces & interfaces of their multiple structural components play critical roles in determining their photocatalytic mechanisms and kinetics. Here, we fabricate an edge-connected MoS2/Au/TiO2 photocatalytic system via a selective photodeposition method and utilize a surface-diffusion mechanism to maximize the synergistic effects among the components. The resultant photocatalytic system behaves as a Z-scheme with well spatially separated redox reaction sites. The optimal catalyst 10 % MS/Au/T exhibited a pseudo 1st-order rate constant of 0.0145 min−1 within 120 min, which is seven times more than that of pristine TiO2. The edge-deposited MoS2 in the nanocomposite serves as a reservoir to adsorb and then transport the pollutant molecules rapidly to TiO2 surface for oxidation. Such a pre-concentration effect, as well as the Z-scheme charge transfer mechanism, has enhanced the overall degradation efficiency, and induced the occurrence of zero-order degradation kinetics. The charge transfer behaviors, the diffusion-enhancement mechanism, zero-order kinetics, and the order transition are then thoroughly studied against the MoS2 mass loading. 10 % MS/Au/T showed the highest values of zero and first-order constants, which were 0.073 ppm/min and 0.011 min−1, respectively. A diffusion-enhanced model is developed and validated to explain the experimental observations. This work provides meaningful insights into degradation enhancement and kinetic analysis for heterostructured photocatalytic systems.
Original language | British English |
---|---|
Article number | 119501 |
Journal | Chemical Engineering Science |
Volume | 284 |
DOIs | |
State | Published - 5 Feb 2024 |
Keywords
- Heterostructure
- Kinetics
- Surface adsorption
- Surface diffusion
- Z-scheme