Dongchu Chen

A new insight into PAM/graphene-based adsorption of water-soluble aromatic pollutants

Graphene materials have been extensively verified as a good adsorbent for tackling wastewater containing various aromatic pollutants; however, little attention has been paid to understanding the graphene-based adsorption mechanism. Here, a systematic work is performed to prepare a series of graphene oxide (GO)-incorporated polyacrylamide hydrogels, with a three-dimensional (3D) monolithic structure, followed by in situ conversion of GO to reduced graphene oxide. Such a method not only enables the prevention of irreversible aggregation of graphene sheets during the in situ reduction, but also facilitates the clarification of the relationship between the structure and adsorption properties of the graphene materials. This work presents two kinds of graphene-based 3D monolithic adsorbents for either selective separation of the cationic aromatic pollutant from anionic one or uptake both of them for the total purification purpose. More importantly, we effectively unravel that the sp2-conjugated carbon network of the graphene materials plays a pivotal role in purifying the aromatic organic pollutants through π–π stacking interactions that outstrip electrostatic attraction interactions. Therefore, the present work is expected to provide an impetus toward exploration of high-performance graphene-based materials for various applications, especially environmental remediation, on the basis of effectively impeding self-aggregation of graphene sheets and judiciously modulating their intrinsic structure.

Cotton fabric-based facile solar photocatalytic purification of simulated real dye wastes

For the first time, this study presents solar photocatalytic processing of the real dye wastes remaining after finishing polyester/cotton (P/C) blends, rather than a pure organic dye solution as widely reported. A commonly used microencapsulation-based one-bath dyeing is investigated systematically, in order to simulate the real dyeing environment and to generate real dye wastes. The generated dye wastes are subsequently tackled by facile cotton fabric-based photocatalytic degradation involving a visible light-active TiO2 photocatalyst under solar light. Importantly, such a TiO2 photocatalyst is prepared without any calcination, doping, or coupling with plasmonic metal nanoparticles or narrow-band-gap semiconductors. As a result, the present visible light-responsive cotton fabric-based photocatalytic degradation of the simulated real dye wastes is expected to stimulate various industries for achieving simultaneous effective dyeing and processing of the dye wastes remained. This study also contributes to energy saving and environmental protection.

A mini review of the synthesis of poly-1,2,3-triazole-based functional materials

As a class of nitrogenous heterocyclic compounds, poly-1,2,3-triazole-based functional materials have recently attracted growing attention across many important scientific areas such as the synthesis of drugs and functional materials. There is therefore an urgent need to perform a review study of such an important class of materials for summarizing the state-of-the-art contributions and for clarifying the direction of the most recent advances (mostly in 2016). Herein, from the perspective of raw material selection and synthetic processes, we conduct a mini review study of the most recent new findings, including technologies and strategies, on the synthesis of macromolecular 1,2,3-triazole-based functional materials, such as various state-of-the-art approaches based on click chemistry and optimization of synthetic conditions like selection of raw materials, control of their concentrations, and selective utilization of different active groups. This mini review also briefly introduces the progress of using poly-1,2,3-triazole-based materials for a broad range of applications including molecular recognition, chemical sensing, drug chemistry, bio-chemistry, and conducting materials, etc.

Improving Visible Light-Absorptivity and Photoelectric Conversion Efficiency of a TiO2 Nanotube Anode Film by Sensitization with Bi2O3 Nanoparticles

This study presents a novel visible light-active TiO2 nanotube anode film by sensitization with Bi2O3 nanoparticles. The uniform incorporation of Bi2O3 contributes to largely enhancing the solar light absorption and photoelectric conversion efficiency of TiO2 nanotubes. Due to the energy level difference between Bi2O3 and TiO2, the built-in electric field is suggested to be formed in the Bi2O3 sensitized TiO2 hybrid, which effectively separates the photo-generated electron-hole pairs and hence improves the photocatalytic activity. It is also found that the photoelectric conversion efficiency of Bi2O3 sensitized TiO2 nanotubes is not in direct proportion with the content of the sensitizer, Bi2O3, which should be carefully controlled to realize excellent photoelectrical properties. With a narrower energy band gap relative to TiO2, the sensitizer Bi2O3 can efficiently harvest the solar energy to generate electrons and holes, while TiO2 collects and transports the charge carriers. The new-type visible light-sensitive photocatalyst presented in this paper will shed light on sensitizing many other wide-band-gap semiconductors for improving solar photocatalysis, and on understanding the visible light-driven photocatalysis through narrow-band-gap semiconductor coupling.

Facile fabrication of raspberry-like composite microspheres for the construction of superhydrophobic films and applications in highly efficient oil–water separation

Inspired by the “lotus effect”, we proposed a facile synthetic route toward raspberry-like PS@SiO2 microspheres, which further lead to superhydrophobic surfaces. In this approach, monodispersed polystyrene (PS) microspheres were first synthesized via dispersion polymerization using polyvinylpyrrolidone (PVP) as stabilizer. The obtained PS microspheres were then used as template microspheres for biomimetic silification using tetraethyl orthosilicate (TEOS) as precursor. Upon adjusting the molecular weight of PVP and the concentration of NH3·H2O, the surface roughness of PS@SiO2 microspheres can be well controlled. Furthermore, after hydrophobization treatment, by drop-casting the raspberry-like PS@SiO2 microspheres onto a glass slide, dual-scale films were obtained, which had a similar surface morphology to that of the lotus leaf, exhibiting a water contact angle of 163.3° and water contact angle hysteresis of 4°. In addition, the oil–water separation ability of hydrophobic raspberry microsphere treated steel mesh was investigated. The results demonstrated excellent oil–water separation efficiency and reusability. This facile and robust synthesis technique for constructing a superhydrophobic surface hold great potential application in versatile and large-scale oil–water separation.

Template-free scalable synthesis of TiO2 hollow nanoparticles for excellent photoelectrochemical applications

With the energy crisis and resource depletion nowadays, novel, highly performing, and cost-effective semiconductors are in urgent demand for efficiently harvesting solar energy for photoelectrochemical applications. Herein, this study presents low-cost anatase TiO2 hollow nanoparticles as prepared by a critical liquid-phase deposition (LPD) processing combined with a hydrothermal reaction and calcination processing, without involving any templates. The additional LPD processing not only makes the resulting samples more visible light responsive, but also results in hollowing the TiO2 nanoparticles (nanosheets vs. hollow nanoparticles). Importantly, commercial TiO2 powder is employed as the starting material to achieve the final synthesis of TiO2 hollow nanoparticles, making it scalable and cost-effective for production and applications. As a by-product, the fluoride, formed during the preparation process, is assumed to play a significant role in hollowing through chemically induced self-transformation and Ostwald ripening, in addition to enhancing the crystallinity. The beneficial structural evolution to the hollow nanoparticles enables the improvement of the photoelectrochemical performance through impressive inhibition of the recombination of the photoelectrons and holes, which is well evidenced by Iph and EIS (Nyquist plot), as well as by I–V curve and electron lifetime evaluations as for the assembled DSSCs with the prepared TiO2 hollow nanoparticles under simulated sunlight illumination (50xa0mW/cm2).

Insights into energy-efficient and eco-friendly sealing of anodic aluminum oxide film holes with alkaline earth metal salts

In this study, the impact of various sealing conditions on the quality of the sealed anodic aluminum oxide (AAO) film is systematically investigated, which leads us to gain insights into sealing the AAO film. To this end, magnesium acetate and calcium acetate are employed as the main compositions of the sealant. It is demonstrated that the temperature exerts the greatest influence on the quality of the sealed film based on the weight loss and antistaining adsorption evaluations among the other examined conditions, followed by pH, mixed salts, surfactants, and complexants. For the optimized sample, the minima of the staining level and weight-loss ratio can reach 0 and 13.4xa0mg dm−2, respectively, meeting the requirement of the ISO standard. This work also realizes an energy-efficient sealing of the AAO film at intermediate temperatures (75–85 °C). The potentiodynamic scanning and electrochemical impedance spectroscopy measurements reveal that the AAO film sealed by the alkaline earth metal salt possesses a superior corrosion resistance as compared to the one sealed by the conventional nickel salt. Additionally, the potential can be stable in a faster way at higher temperatures over the range of 70–85 °C, as demonstrated in the E–t curve. On the other hand, the potential stabilization is more readily achieved at higher pH values within the range of 5–7, whereas it cannot be realized at pH values above 7. We also note that the appropriate addition of surfactant, complexant and pH buffer can assist in stabilizing the potential. In the absence of any surfactants and complexants, the potential stabilization cannot be reached. Furthermore, the present study discusses the mechanism underlying the effective sealing, thereby paving the way for the future exploration of the energy-efficient and eco-friendly sealing technologies for many practical AAO-based applications.