Shuanglong Lin

Dramatic activity of a Bi2WO6@g-C3N4 photocatalyst with a core@shell structure

Here we report a Bi2WO6@g-C3N4 core@shell structure which was prepared by a combined ultrasonication–chemisorption method with enhanced photocatalytic degradation. The composites were extensively characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS). Compared with bare Bi2WO6 and g-C3N4, the Bi2WO6@g-C3N4 composites exhibited significantly enhanced photocatalytic activity for methylene blue (MB) degradation under visible light irradiation. The 3 wt% Bi2WO6@g-C3N4 showed the highest photocatalytic activity under visible light irradiation, which was about 1.97 times higher than Bi2WO6. In addition, the quenching effects of different scavengers displayed that the reactive h+ and ˙O2− play the major role in the MB decolorization. The core@shell hybrid photocatalyst exhibited dramatically enhanced photo-induced electron–hole separation efficiency, which was confirmed by the results of photocurrent and EIS measurements. On the basis of the experimental results and estimated energy band positions, a mechanism for the enhanced photocatalytic activity was proposed.

Cu2O NPs decorated BiPO4 photo-catalyst for enhanced organic contaminant degradation under visible light irradiation

The surface of BiPO4 was decorated with Cu2O nanoparticles (NPs) (hereafter designed as Cu2O/BiPO4) via an interfacial self-assembly method. The physical and photophysical properties of the Cu2O/BiPO4 hybrid photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray fluorescence spectrometry (XRF), UV-vis diffuse reflectance spectroscopy (DRS) and photo-electro-chemical (PEC). Compared with bare BiPO4 and Cu2O, the Cu2O/BiPO4 composites exhibited significantly enhanced photocatalytic activity for methylene blue (MB) degradation under visible light irradiation. The 5 wt% Cu2O/BiPO4 showed the highest photocatalytic activity under visible light irradiation, which was about 12.25 times that of BiPO4. Significantly, the superior stability was also observed in the five cyclic runs. The Cu2O/BiPO4 hybrid photocatalysts exhibited dramatically enhanced photo-induced electron–hole separation efficiency, which was confirmed by the results of photocurrent measurements. On the basis of the experimental results and estimated energy band positions, the mechanism of enhanced photocatalytic activity was proposed.

Growth of nano Ag@AgCl on (111) facets of Cu2O microcrystals with an enhanced photocatalytic activity

Single crystalline Cu2O nanoparticles were synthesized under mild conditions. A Ag@AgCl/Cu2O photocatalyst was prepared by directly growing Ag@AgCl nanoparticles (NPs) on (111) facets of octahedral Cu2O via a facile precipitation in situ photoreduction method. The results indicate that Ag@AgCl nanoparticles have a narrow size distribution ranging from 10 to 50 nm and are uniformly distributed on the surface of Cu2O nanoparticles. The surface area of the composite reached up to 19.736 m2 g−1. The photocatalytic performance of the Ag@AgCl/Cu2O composite for the degradation of methylene blue (MB) was evaluated under visible light irradiation. The Ag@AgCl/Cu2O composite with 30 wt% Ag@AgCl showed the highest photocatalytic activity, degrading 93.61% MB after 2 h irradiation. The high photocatalytic activity of the Ag@AgCl/Cu2O composite can be attributed to its high surface area, the crystal effect of Cu2O and the surface plasmon resonance of the Ag NPs. In addition, the Ag@AgCl/Cu2O composite can be used as a photocatalyst for the degradation of phenol. Based on these experimental results, a photocatalytic mechanism for the degradation of hazardous chemical effluents over Ag@AgCl/Cu2O photocatalysts was proposed. The free radicals and holes act as the main reactive species during the degradation.

Oil-in-Water Self-Assembled Synthesis of Ag@AgCl Nano-Particles on Flower-like Bi2O2CO3 with Enhanced Visible-Light-Driven Photocatalytic Activity

In this work, a series of novel flower-like Ag@AgCl/Bi2O2CO3 were prepared by simple and feasible oil-in-water self-assembly processes. The phase structures of as-prepared samples were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), X-ray fluorescence spectrometer (XRF), etc. The characterization results indicated that the presence of Ag@AgCl did not affect the crystal structure, but exerted a great influence on the photocatalytic activity of Bi2O2CO3 and enhanced the absorption band of pure Bi2O2CO3. The photocatalytic activities of the Ag@AgCl/Bi2O2CO3 samples were determined by photocatalytic degradation of methylene blue (MB) under visible light irradiation. The Ag@AgCl (10 wt %)/Bi2O2CO3 composite showed the highest photocatalytic activity, degrading 97.9% MB after irradiation for 20 min, which is over 1.64 and 3.66 times faster than that of pure Ag@AgCl (calculated based on the equivalent Ag@AgCl content in Ag@AgCl (10 wt %)/Bi2O2CO3) and pure Bi2O2CO3, respectively. Bisphenol A (BPA) was also degraded to further prove the degradation ability of Ag@AgCl/Bi2O2CO3. Photocurrent studies indicated that the recombination of photo-generated electron–hole pairs was decreased effectively due to the formation of heterojunctions between flower-like Bi2O2CO3 and Ag@AgCl nanoparticles. Trapping experiments indicated that O2−, h+ and Cl° acted as the main reactive species for MB degradation in the present photocatalytic system. Furthermore, the cycling experiments revealed the good stability of Ag@AgCl/Bi2O2CO3 composites. Based on the above, a photocatalytic mechanism for the degradation of organic compounds over Ag@AgCl/Bi2O2CO3 was proposed.

Facile hydrothermal synthesis of plasmonic photocatalyst Ag@AgCl and degradative photocatalysis under visible light irradiation

We put forward a new approach for the synthesis of Ag@AgCl plasmonic photocatalyst via a hydrothermal-deposition-photoreduction method. The cetylmethylammonium chloride (CTAC) was used alone as both a source of reactants and surfactant. The structure of the prepared photocatalyst was determined by XRD, SEM, EDX and UV-Vis spectroscoscopy. The photocatalytic properties were investigated by degradation of an organic pollutant, Rhodamine B, under visible light irradiation. The results reveal that the experimental conditions have a great effect on the morphology of Ag@AgCl crystals. Ag@AgCl crystal is cubic and the Ag@AgCl sample which is photoreduced for 40 min exhibits the highest photoactivity, and 80.6 % RhB is degraded after irradiation for 2 hours using this catalyst. The high photocatalytic activity observed is attributed to the surface plasmon resonance effect of Ag nanoparticles.

Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi2O2CO3 Dotted with Ag@AgBr

A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi2O2CO3 micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi2O2CO3, flower-like Ag@AgBr/Bi2O2CO3 micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi2O2CO3 composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB) after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi2O2CO3, respectively. Bisphenol A (BPA) was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi2O2CO3. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi2O2CO3 was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen).

An oil-in-water self-assembly synthesis, characterization and photocatalytic properties of nano Ag@AgCl surface-sensitized K{sub 2}Ti{sub 4}O{sub 9}

Highlights: • The plasmatic Ag@AgCl surface-sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts. • Ag@AgCl greatly increased visible light absorption for K{sub 2}Ti{sub 4}O{sub 9}. • The photocatalysts exhibited enhanced photocatalytic dye degradation. - Abstract: Nano-sized plasmonic Ag@AgCl surface-sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts (hereafter designated as Ag@AgCl/K{sub 2}Ti{sub 4}O{sub 9}) was synthesized via a facile oil-in-water self-assembly method. The photocatalytic activity of the prepared materials for RhB (Rhodamine B) degradation was examined under visible light irradiation. The results reveal that the size of Ag@AgCl, which evenly dispersed on the surface of K{sub 2}Ti{sub 4}O{sub 9}, distributes about 20–50 nm. The UV–vis diffuse reflectance spectra indicate that Ag@AgCl/K{sub 2}Ti{sub 4}O{sub 9} samples have a significantly enhanced optical absorption in 380–700 nm. The photocatalytic activities of the Ag@AgCl/K{sub 2}Ti{sub 4}O{sub 9} samples increase first and then decrease with increasing amount of loading Ag@AgCl and the Ag@AgCl(20 wt.%)/K{sub 2}Ti{sub 4}O{sub 9} sample exhibits the best photocatalytic activity and 94.47% RhB was degraded after irradiation for 2 h. Additionally, studies performed using radical scavengers indicated that O{sub 2}·{sup −} and Cl{sup 0} acted as the main reactive species. The electronic interaction was systematically studied and confirmed by the photo-electrochemical measurements.