Core–Shell Structural CdS@SnO₂ Nanorods with Excellent Visible-Light Photocatalytic Activity for the Selective Oxidation of Benzyl Alcohol to Benzaldehyde

Core–shell structural CdS@SnO₂ nanorods (NRs) were fabricated by synthesizing SnO₂ nanoparticles with a solvent-assisted interfacial reaction and further anchoring them on the surface of CdS NRs under ultrasonic stirring. The morphology, composition, and microstructures of the obtained samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption–desorption. It was found that SnO₂ nanoparticles can be tightly anchored on the surface of CdS NRs, and the thickness of SnO₂ shells can be conveniently adjusted by simply changing the addition amount of SnO₂ quantum dots. UV–vis diffuse reflectance spectrum indicated that SnO₂ shell layer also can enhance the visible light absorption of CdS NRs to a certain extent. The results of transient photocurrents and photoluminescence spectra revealed that the core–shell structure can effectively promote the separation rate of electron–hole pairs and prolong the lifetime of electrons. Compared with the single CdS NRs, the core–shell structural CdS@SnO₂ exhibited a remarkably enhanced photocatalytic activity for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) under visible light irradiation, attributed to the more efficient separation of electrons and holes, improved surface area, and enhanced visible light absorption of core–shell structure. The radical scavenging experiments proved that in acetonitrile solution, ·O₂– and holes are the main reactive species responsible for BA to BAD transformation, and the lack of ·OH radicals is favorable to obtaining high reaction selectivity

Ecofriendly Synthesis and Photocatalytic Activity of Uniform Cubic Ag@AgCl Plasmonic Photocatalyst

Uniform cubic Ag@AgCl plasmonic photocatalyst was synthesized by a facile green route in the absence of organic solvent, in which a controllable double-jet precipitation technique was employed to fabricate homogeneous cubic AgCl grains and a photoreduction process was used to produce Ag nanoparticles (NPs) on the surface of AgCl. During the double-jet precipitation process, the presence of gelatin and Cl^– ions at low concentration was necessary for the formation of cubic AgCl grains. Atomic force microscopy (AFM) was used to probe the morphological structure of Ag@AgCl grains for the first time, which showed that Ag NPs are anchored on the surface of AgCl grains like up-and-down mounds. Further characterization of the photocatalyst was also done by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–visible diffuse reflectance spectroscopy (DRS). The as-prepared Ag@AgCl plasmonic photocatalyst exhibited excellent photocatalytic efficiency for the degradation of the azo dye acid orange 7 (AO7), phenol, and 2,4-dichlorophenol (2,4-DCP). The photocatalytic mechanism was studied by radical-trapping experiments and the electron spin resonance (ESR) technique with 5,5-dimethyl-1-pyrroline <i>N</i>-oxide (DMPO), and the results indicated that ^•O₂^– and Cl⁰ are responsible for the rapid degradation of organic pollutants under visible-light irradiation

Facile Tailoring of Anatase TiO₂ Morphology by Use of H₂O₂: From Microflowers with Dominant {101} Facets to Microspheres with Exposed {001} Facets

A facile hydrothermal route employing H₂O₂ as structure-directing agent was explored to fabricate anatase microflowers with dominant {101} facets and anatase microspheres with exposed {001} facets. The influence of H₂O₂ concentration on crystal structure, morphology, and facet composition of TiO₂ was investigated in detail. H₂O₂ plays a crucial role in determining the crystal structure, morphology, and exposed facets of TiO₂. The presence of H₂O₂ favors the formation of anatase phase. When the concentration of H₂O₂ was in the range 0.7–3.3 M, anatase microflowers with dominant {101} facets were produced. In contrast, when the concentration of H₂O₂ was higher than 6.6 M, anatase microspheres with exposed {001} facets were formed. A mechanism was proposed to account for the influence of H₂O₂ on crystal structure and morphology of TiO₂. Photocatalytic degradations of rhodamine B and 2,4-dichlorophenol indicated that anatase microspheres with exposed {001} facets showed much higher photocatalytic activity than anatase microflowers with dominant {101} facets

Z‑Scheme BiOCl-Au-CdS Heterostructure with Enhanced Sunlight-Driven Photocatalytic Activity in Degrading Water Dyes and Antibiotics

Although semiconductor photocatalysis has made great progresses as a promising solution to solve the problem of environmental pollution, the highly efficient decomposition of organic pollutants driven by sunlight is still a challenge. Herein, we successfully constructed a Z-scheme photocatalyst BiOCl-Au-CdS for the first time by stepwise deposition of Au and CdS. It was found that the Au nanoparticles (NPs) were selectively anchored on the {001} facets of BiOCl nanosheets in the process of photoreduction while CdS NPs were further in situ deposited on Au NPs via the strong S–Au interaction. Compared to BiOCl, BiOCl-Au, and BiOCl-CdS, the Z-scheme BiOCl-Au-CdS exhibited evidently higher sunlight-driven photocatalytic activity toward the degradations of anionic dye Methyl Orange, cationic dye Rhodamine B, colorless pollutant phenol, and antibiotic sulfadiazine. The radical trapping experiments indicated that ·OH, h⁺, and ·O₂^– are the main reactive species responsible for the degradations of organic pollutants over BiOCl-Au-CdS. Based on the photoelectrochemical measurements, PL spectra, and band potential calculation, it can be concluded that the Z-scheme structure of BiOCl-Au-CdS not only retains the photogenerated electrons and holes with higher redox ability but also decreases their recombination rate. As a highly efficient sunlight driven photocatalyst, BiOCl-Au-CdS can be potentially used in environmental pollutant remediation