Shixiang Zuo

Preparation of polyaniline/graphene composites with excellent anti-corrosion properties and their application in waterborne polyurethane anticorrosive coatings

Polyaniline, a novel conductive polymer, has been widely used as an anti-corrosive filler. In order to further improve the anti-corrosion performance, polyaniline/graphene (PANI/RGO) composites were prepared by in situ polymerization. And PANI/RGO composite anti-corrosion coatings were also prepared using PANI/RGO as anti-corrosive filler and waterborne polyurethane (WPU) as matrix. The anti-corrosion properties were proven by potentiodynamic polarization curves (Tafel polarization curves), electrochemical impedance spectroscopy and salt spray test analysis of the WPU anti-corrosive coatings. The results showed that the obtained composite coatings reinforced by 0.75 wt% of PANI/RGO composites possessed superior anti-corrosive performance when the graphene content of the filler was 4 wt%.

In situ fabrication of Ce1−xLaxO2−δ/palygorskite nanocomposites for efficient catalytic oxidation of CO: effect of La doping

Novel palygorskite (PG) supported Ce1−xLaxO2−δ nanocomposites were prepared by a facile in situ deposition method using hexamethylenetetramine as the precipitant. The textural and structural properties of the products were characterized by XRD, HRTEM, FT-IR, Raman, XPS and TPR techniques. The results indicated that the oxide particles with an average size of about 5 nm were loaded successfully onto the surface of PG rods and were uniformly dispersed. The catalytic activities of Ce1−xLaxO2−δ/PG (x from 0.1 to 0.9) for CO oxidation were investigated. La3+ doping was found to have critical effects on the CO oxidation activity. The best Ce1−xLaxO2−δ/PG nanocomposite was obtained when the x value was adjusted to 0.5, and the reaction rate was found to be three times higher than that of a commercial CeO2 catalyst. Adequate introduction of La3+ promotes the formation of non-stoichiometric Ce1−xLaxO2−δ and is responsible for the formation of oxygen vacancies and surface superoxide ions. However, when the doping ratio increases to 0.6 or higher, co-precipitation of La2O3 leads to decreased redox properties and CO oxidation activity.

Spectroscopic Studies on the Interaction Between Troxerutin and Bovine Hemoglobin

The interaction of bovine hemoglobin (BHb) with troxerutin was investigated by UV–Vis absorption spectra and fluorescence spectra methods, circular dichroism spectra, and the freeze-fractured TEM methods. Results showed that troxerutin causes the fluorescence quenching of BHb through a static quenching mechanism. The binding constant KA and number of binding sites n of troxerutin with BHb were obtained. Positive values of the thermodynamic parameters enthalpy change and entropy change indicate that the interaction between troxerutin and BHb is driven mainly by electrostatic interactions. This shows that the binding is spontaneous at the standard state since the change in the standard Gibbs energy value is negative. The average binding distance between the donor (BHb) and the acceptor (troxerutin) was assessed from the Förster theory. The present study suggests that the thermal stability of BHb is enhanced upon binding with troxerutin.

Black phosphorus quantum dots/attapulgite nanocomposite with enhanced photocatalytic performance

Novel black phosphorus quantum dots/attapulgite (BPQDs/ATP) nanocomposites were prepared via a facile hydrothermal-deposition method. TEM showed that BPQDs dispersed evenly on the surface of ATP with uniform particle size about 5nm. UV-Vis revealed that the BPQDs/ATP composite showed wider visible light absorption range as compared with pure ATP. The photocatalytic activity was evaluated by degradation of bisphenol A (BPA). Results showed that BPQDs/ATP reached 90% degradation rate under solar light irradiation for 180min. The coherent heterostructure formed by BPQDs and ATP was responsible for the enhanced photocatalytic performance, due to the sensitization effect of BPQDs and the facilitation of charges separation.

One-Pot Preparation of Graphene-Based Polyaniline Conductive Nanocomposites for Anticorrosion Coatings

Graphene-based polyaniline (PANI/RGO), used as conductive filler, was synthesized through a new one-pot emulsion polymerization technology. Graphene dispersion (RGO) was obtained by ultrasonically reducing graphene oxide (GO) in a hot sodium hydroxide solution in the absence of any toxic reductant, such as hydrazine hydrate. Sodium dodecyl benzene sulfonate (SDBS), in which RGO sheets were dispersed, was synthesized using dodecyl benzenesulfonic acid (DBSA) and NaOH. In this RGO/SDBS mixture, polyaniline (PANI), doped with multiple acids (HCl-DBSA), was then uniformly polymerized on the surface of the RGO sheets. The experimental results showed that this reaction improved the dispersion of the RGO in the PANI system, and increased the homogeneous distribution of the formed PANI particles on the RGO surface. The synthesized composite material (PANI/RGO) had good thermal stability, electrical conductivity (about 11.71S⋅cm−1) and water dispersibility. Based on its excellent properties, the PANI/RGO was combined with waterborne epoxy resin to prepare anticorrosion coatings. The corrosion resistance of these coatings was studied using Tafel plots, along with other critical properties tested by the national standards. The results suggested that the surface resistivity of the coatings could be as high as 2.48×108Ω with the addition around 3wt.% of the PANI/RGO meeting good antistatic standards. In addition, the antistatic coatings had outstanding corrosion resistance, as well as tremendous physical and chemical properties.

Z-Scheme Photocatalyst Constructed by Natural Attapulgite and Upconversion Rare Earth Materials for Desulfurization

The Er3+:CeO2/ATP (attapulgite) nanocomposites were prepared by a facile precipitation method. The samples were characterized by various measurements. XRD and TEM showed that Er3+:CeO2 nanoparticles were well-crystallized and loaded on the surface of ATP. The visible light was converted into ultraviolet light by Er3+:CeO2 as evidenced by upconversion photoluminance (PL) analysis. The mass ratio of Er3+:CeO2 to ATP on the desulfurization efficiency was investigated. Results showed that the desulfurization rate reached 87% under 4 h visible light irradiation when the mass ratio was 4:10. The mechanism was put forward as follows. Er3+:CeO2 and ATP formed Z-scheme heterostructure intermediated by oxygen vacancy, leading to the enhanced separation of photogenerated charges and preservation of high oxidation-reduction potential, both of which favored for the generation of radicals to oxidize sulfur species.

Surface Treatment of Broad-Spectrum Ultraviolet Light Shielding Titania/Zinc Oxide Composites and Their Applications in Sunscreens

Nano-titanium oxide (TiO2) and zinc oxide (ZnO) are widely used in sunscreen products, but many shortcomings for these both oxides still exist. In this paper, the hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol solution was used to deposit inorganic silica nano-coating on the surface of TiO2/ZnO composite, followed by grafting by organosilane. The as-prepared products were characterized by XRD, FTIR, TG and TEM. In addition, Zeta potential, color difference test, dissolution experiments of zinc ions and water contact angle tests were used to characterize the effect of inorganic silica coating and organosilane grafting. Subsequently, the modified TiO2/ZnO composites were applied into the sunscreen formulation and the properties of the as-prepared emulsions were evaluated by the distribution analysis of the particle size, acceleration test and ultraviolet transmittance analyzer. The results showed that the sunscreen emulsion prepared by the TiO2/ZnO composite has better sun protection performance and stability than the emulsion prepared by the mixture of TiO2 and ZnO.

Preparation of rutile TiO2@avobenzone composites for the further enhancement of sunscreen performance

It is well known that organic avobenzone and inorganic TiO2 are applied to shield UVA and UVB, respectively. However, some of the disadvantages of the individual components are inevitable in sunscreens. Herein, avobenzone was coated on the surface of pretreated TiO2 for the preparation of a TiO2@avobenzone broad-spectrum sunscreen. The as-prepared products were characterized via XRD, FTIR, TG and SEM. The organic film-layer was evenly encapsulated on the surface of the pretreated TiO2 to assemble a core–shell structure. Subsequently, TiO2@avobenzone was applied to a formulation and the properties of the obtained emulsion were evaluated via droplet size distribution analysis, HPLC and an ultraviolet transmittance analyzer. The results show that TiO2@avobenzone possesses more excellent dispersity, lower degradation rate and higher SPF value as compared to the individual components in the formulated emulsion, and thus, TiO2@avobenzone could be used as a potential candidate for sunscreens.