Mingjun Zhou

Transfer Charge and Energy of Ag@CdSe QDs-rGO Core–Shell Plasmonic Photocatalyst for Enhanced Visible Light Photocatalytic Activity

Plasmonic heteronanostructures in semiconductor type display extraordinary photocatalytic efficiency induced by the plasmonic energy that operates in the Ag@CdSe-rGO hybrid ternary composites. The obtained plasmonic photocatalysts in nanoscale were fabricated by using a one-step hydrothermal method, during which the in situ nucleation of Ag@CdSe core-shell nanoparticles and the reduction of GO to rGO occurred simultaneously. Three different roles of Ag core and the junction of synergistic properties arising from the introduced rGO jointly enhanced the optical properties of CdSe. Localized plasmon resonance (LPR) effects of plasmonic Ag contribute to the separation of photogenerated e(-)/h(+) pairs via the electrons and resonant energy transfer. Electrochemical investigations have further confirmed the enhanced separation of the photogenerated e(-)/h(+) pairs. From comparative photocatalytic experiments of Ag@CdSe-rGO and Ag/CdSe-rGO, the plasmonic effect of the Ag core in the Ag@CdSe-rGO nanostructure serves to prolong the charge separation under visible light beyond common attached trimers.

Enhanced photocatalytic degradation of tetracycline antibiotics by reduced graphene oxide–CdS/ZnS heterostructure photocatalysts

In this work, reduced graphene oxide (RGO)–CdS/ZnS heterostructure composites have been successfully synthesized by a hydrothermal method by assembling the CdS/ZnS heterostructure nanoparticles on RGO sheets and the reduction of GO occurs simultaneously. The as-prepared RGO–CdS/ZnS composites with the content of 15% RGO exhibit highly active photodegradation of TC. A possible mechanism for the enhanced photocatalytic activity has been discussed. The CdS/ZnS heterostructure facilitates the transformation of electrons, which is excited by light irradiation in the conduction band of CdS. RGO is supposed to be an electron transfer channel, which is used to reduce the recombination of electron–hole pairs, thus enhancing the photo-conversion efficiency. By profiting from the synergy of RGO and CdS/ZnS heterostructure, the photocatalysts not only show a better photocatalytic activity in tetracycline antibiotics but also prevent pure CdS or ZnS from photocorrosion. At last, RGO–CdS/ZnS shows remarkable stability and cyclic performances.

Hydrothermal synthesis and enhanced visible-light photocatalytic activity of octahedral Bi2WO6 modified with CdSe quantum dots

In this paper, octahedral Bi2WO6 modified with CdSe quantum dots was synthesized by a hydrothermal method. This as-prepared CdSe–Bi2WO6 photocatalyst exhibited a higher photocatalytic activity for the degradation of tetracycline (TC) than octahedral Bi2WO6. Moreover, 15%-CdSe–85%-Bi2WO6 showed the best Dr of 65.38%, which is over 5 times that of the pure Bi2WO6. Furthermore, the as-synthesized CdSe–Bi2WO6 composite photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis) and photoluminescence spectroscopy (PL).

One-step hydrothermal synthesis of cobalt and potassium codoped CdSe quantum dots with high visible light photocatalytic activity

The effect of metal ion doping on the electronic structure and optical properties of CdSe quantum dots has been investigated by various characterization techniques and experiments. Various cation codoped CdSe quantum dot photocatalysts were synthesized via a hydrothermal method. The prepared quantum dots were examined using X-ray diffraction, fluorescence spectroscopy, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The activities of the photocatalysts were evaluated with respect to the photodegradation of tetracycline hydrochloride solutions under simulated sunlight irradiation. 3%Co–4%K/CdSe quantum dots showed a higher photocatalytic activity than others within 30 min of visible light irradiation. Furthermore, there was hardly any decrease in the catalytic efficiency after the fourth experimental cycle. Identification data illustrate that Co and K codoping may cause improvement in the photocatalytic performance of CdSe quantum dots, which is crucial for tetracycline hydrochloride degradation under simulated sunlight irradiation. Therefore, this study demonstrates a promising strategy for the design of highly efficient photocatalysts for the remediation of aqueous pollutants.

Microwave-Assisted Fabrication of Recyclable CdS/Fe3O4/rGO Photocatalysts to Improve the Photocatalytic Performance Under Visible Light

A unique CdS/Fe3O4/rGO composite photocatalyst is successfully synthesized by the microwave method. It displays promising photocatalytic activity towards the photo-degrading of tetracycline (TC) in aqueous solution, the degradation rate of TC is 69% with adding 0.1g CdS/Fe3O4/rGO photocatalyst into 20mg/L tetracycline for 2h under visible light irradiation. Furthermore, the mechanism was systematically investigated by active species trapping experiment. It can be known that e− was the major active species in the photodegradation process and the possible process of charge transfer for CdS/Fe3O4/rGO was proposed based on the experimental results. The as-prepared samples were carefully evaluated by XRD, TEM, XPS, VSM, PL spectra, Raman spectrometer.