Yanjie Wang

Preparation of 2D hydroxyl-rich carbon nitride nanosheets for photocatalytic reduction of CO2

Hydroxyl-rich g-C3N4 nanosheets were prepared by ultrasonic exfoliation of bulk g-C3N4 in water. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, UV-vis absorption spectroscopy, photoluminescence spectroscopy, time-resolved fluorescence decay spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and photocurrent response. The results indicated that the bulk g-C3N4 was exfoliated to five or six layers. The specific surface area increased from 8.66 m2 g−1 for the bulk g-C3N4 to 26.48 m2 g−1 for the nanosheets. More importantly, the amount of hydroxyl group on the g-C3N4 surface increased greatly upon ultrasonic treatment in water. Meanwhile, the separation rate of charge carriers was improved greatly and the conduction band potential shifts to a more negative value. All these can explain the enhanced activity of g-C3N4 nanosheets for visible-light photocatalytic reduction of CO2.

Preparation of thickness-tunable BiOCl nanosheets with high photocatalytic activity for photoreduction of CO2

BiOCl nanosheets with different percentages of exposed {001} facets were prepared by a controlled facile hot-injection technique. The synthesis was conducted using bismuth chloride as a metal precursor, octadecene as a solvent, and oleic acid, oleylamine and octadecene as morphology-control agents. The presence of trace amounts of water in the reaction system leads to mild hydrolysis. The obtained BiOCl nanosheets with highly exposed {001} facets exhibited high activity for photocatalytic reduction of CO2 to CH4. Moreover, the thinner the nanosheets, the higher the production yield. The detailed mechanism has been studied. This work may afford a feasible protocol for the preparation of BiOCl nanosheets with high photocatalytic activity.

Photocatalytic Reduction of CO2 over Heterostructure Semiconductors into Value-Added Chemicals

Photoreduction of CO2 , which utilizes solar energy to convert CO2 into hydrocarbons, can be an effective means to overcome the increasing energy crisis and mitigate the rising emissions of greenhouse gas. This article covers recent advances in the CO2 photoreduction over heterostructure-based photocatalysts. The fundamentals of CO2 photoreduction and classification of the heterostructured photocatalysts are discussed first, followed by the latest work on the CO2 photoreduction over heterostructured photocatalysts in terms of the classification of the coupling semiconductors. Finally, a brief summary and a perspective on the challenges in this area are presented.

Effects of structural, optical and ferromagnetic states on the photocatalytic activities of Sn–TiO2 nanocrystals

The structural, electronic, magnetic and photocatalytic properties of Sn doped TiO2 diluted magnetic semiconductor nanoparticles (NPs) prepared by a simple hydrothermal method were systematically investigated by various conventional techniques and 119Sn Mossbauer spectroscopy. Anatase, mixed (anatase–rutile) and rutile phases of Sn–TiO2 NPs were obtained by adding different amounts of SnCl4 into a titanium nitrate aqueous solution. Photocatalytic degradation of methyl orange and phenol derivatives (RPhOH) were studied under visible and UV light irradiation in water, respectively. The photocatalytic activities of prepared NPs were found to be drastically related to the structural, optical and ferromagnetic properties. A significant relationship was observed between the Hammett substitution constants of RPhOH and the photocatalytic activity. Among all the samples, the anatase phase with low Sn content performed with the best photocatalytic and ferromagnetic characteristics at room temperature.

Versatile rattle-type magnetic mesoporous silica spheres, working as adsorbents and nanocatalyst containers

Abstract The well-defined rattle-type magnetic silica nanocomposite had been synthesized through a facile sol–gel process accompanied by a hard-template method. Structural characterizations indicated that the fabricated nanocomposite, denoted as γ-Fe2O3@SiO2–@mSiO2, was composed of nonporous silica-coating magnetic iron oxide encapsulated in mesoporous silica hollow sphere. The textural parameters of the nanocomposite are adjustable by controlling the preparation conditions. The unique structure of the prepared nanocomposite showed relatively high methylene blue adsorption capability and can be used for removal of dye from aqueous solution. In addition, some active metallic nanoparticles (such as Pt, Pd) can be introduced into the cavity of γ-Fe2O3@SiO2–@mSiO2 to construct confined integrated catalytic system. The designed Pt-based integrated nanocatalyst exhibited not only high activity and selectivity, but also an excellent reusability for the selective hydrogenation of nitrobenzol to aniline. The existence of magnetic core in the nanocomposite provides a facile separation from liquid solution.Graphical AbstractRattle-type nanocomposite with nonporous silica-coating magnetic iron oxide nanoparticles encapsulated in mesoporous silica hollow sphere had been prepared. This unique nanocomposite exhibits excellent adsorption capability for methylene blue dye. After loaded with Pt nanoparticles, the formed functional nanoreactor is very active for selective hydrogenation of nitrobenzol to aniline and shows outstanding reusability.

Synergistic Effect of Charge Generation and Separation in Epitaxially Grown BiOCl/Bi2S3 Nano-Heterostructure

Nano-heterostructures are widely used in the field of optoelectronic devices, and an optimal proportion usually exists between the constituents that make up the structures. Investigation on the mechanism underlying the optimal ratio is instructive for fabricating nano-heterostructures with high efficiency. In this work, BiOCl/Bi2S3 type-II nano-heterostructures with different Bi2S3/BiOCl ratios have been prepared via epitaxial growth of Bi2S3 nanorods on BiOCl nanosheets with solvothermal treatment at different sulfuration temperatures (110-180 °C) and their photoelectrochemical (PEC) performances as photoanodes have been studied. Results indicate that the Bi2S3 content increases with the sulfuration temperature. BiOCl/Bi2S3-170 (i.e., sulfurized@170 °C) exhibits the highest PEC performance under visible-light illumination, whereas BiOCl/Bi2S3-180 with the maximum Bi2S3 content shows the highest visible-light absorption, i.e., possessing the best potential for charge generation. Further analysis indicates that the BiOCl/Bi2S3 heterojunction interface is also crucial in determining the PEC performance of the obtained heterostructures by influencing the charge separation process. With increasing Bi2S3 content, the interface area in the BiOCl/Bi2S3 nano-heterostructures increases first and then decreases due to the mechanical fragility of the nanosheet-nanorod structure and the structural instability in the [010] direction of Bi2S3 with higher Bi2S3 content. Therefore, the increasing content of the Bi2S3 does not necessarily correspond to higher heterojunction area. The optimal performance of BiOCl/Bi2S3-170 results from the maximum of the synthetic coordination of the charge generation and separation. This is the first time ever to figure out the detailed explanation of the optimal property in the nano-heterostructures. The result is inspiring in designing high-performance nano-heterostructures from the point of synthesizing morphological mechanically robust heterostructure and structurally stable constituents to reach a high interfacial area, as well as high light-absorption ability.