Defective Carbon Nitride with Dual-surface Engineering for Highly Efficient Photocatalytic Hydrogen Evolution under Visible Light Irradiation.

Defective carbon nitride (DCN-x) was synthesized through a dual-surface engineering process consisting of nitric acid treatment followed by high-temperature calcination. This process endowed DCN-x with a porous structure and a larger surface area than that of pure graphite carbon nitride (CN), enhancing its visible light absorption and reducing the electron-hole recombination rate. Consequently, DCN-x demonstrated a significantly more efficient photocatalytic hydrogen evolution, with the optimum sample, DCN-600, achieving an activity 55.9 times greater than that of pure CN, while maintaining excellent photocatalytic stability. Furthermore, the presence of tri-s-triazine (heptazine) structures within the CN's in-plane structure was identified as a critical factor for band gap optimization, suggesting new avenues for the synthesis of carbon nitride variants with enhanced photocatalytic performance.

In Situ Decoration of Bi2S3 Nanosheets on Zinc Oxide/Cellulose Acetate Composite Films for Photodegradation of Dyes under Visible Light Irradiation.

A novel Bi2S3-zinc oxide/cellulose acetate composite film was prepared through a blending-wet phase conversion and in situ precipitate method. The results revealed that the incorporation of Bi2S3 in the film increased the cavity density and uniformity, which provided additional space for the growth of active species and improved the interaction between dye pollutants and active sites. Zinc oxide acted as a mediator to facilitate the separation of electron-hole pairs effectively preventing their recombination, thus reducing the photo-corrosion of Bi2S3. As a result, the Bi2S3-ZnO/CA composite film exhibited favorable photocatalytic activity in the degradation of various dyes. Additionally, the composite film displayed effortless separation and recovery without the need for centrifugation or filtration, while maintaining its exceptional catalytic performance even after undergoing various processes.

Contagious degradation of a chemically active surface on the cathodes of lithium-ion batteries.

Durability is critically important in energy storage applications. Based on the model of the contagious degradation of a chemically active surface (CDCAS), a general model for durability has been systematically built. In practical lithium-ion batteries (LIBs), gassing swelling, limited by slow electrochemical processes, occurs over years of use and causes the LIB cell to rupture at an unpredictable moment. As an example of an application, the proposed CDCAS model was used to quantitatively study the gassing behaviors of different LIB systems, resulting in important information that can be used to predict swelling and avoid an accident. Interestingly, what could be deduced from the high nickel system (NCM811) model is that the active reaction area directly degrades to an inactive area without passing through an intermediate active area. The new degradation mechanism of the NCM811 cathode is further supported by the constant activation energy of the charge-transfer (Ea = 0.65 eV) across the whole high temperature storage test. This information shows that it was only partially correct, and even sometimes wrong, to use the increased thickness of the reconstructed rock-salt layer on the surface of some high-Ni cathode particles as an indicator of an increase in the impedance. The in-depth understanding on cathode degradation using the CDCAS model presented in this work will be beneficial for the development of high-safety and high-performance LIBs.

Modified nano-SiO2/PU hydrophobic composite film prepared through in-situ coupling by KH550 for oil-water separation.

In this study, hydrophobic polymer composite films based on polyurethane (PU) were prepared for oil-water separation. Hydrophilic fumed silica (nano-SiO2) was introduced as reinforcing filler, and silane coupling agent (KH550) was used to crosslink PU with nano-SiO2 in situ for enhancing the nano-SiO2 dispersion in the films. The microscopic morphology, crystalline structure, and hydrophobic properties of the films were characterized by using scanning electron microscopy, X-ray diffraction, FTIR spectroscopy, water contact angle, and water absorption tests. The results showed that the hydrophobicity of the nano-SiO2/PU composite films increased with the addition of nano-SiO2. KH550 not only significantly promoted the crosslink action between PU and nano-SiO2 but also enhanced the dispersion of nano-SiO2 in the composite films. Moreover, the pore structure of the prepared films was changed with the addition of nano-SiO2 and KH550, which greatly improved the hydrophobicity. The test results for oil-water separation performance showed that the prepared composite films can efficiently separate the oil from oil-water mixtures with good repeatability.

Fabrication of two-phase Ca2+-doped LaVO4:Eu3+ structures: morphology modification, tunable optical performance and detection of Fe3+ ions with high sensitivity.

Two-phase Ca2+-doped LaVO4:Eu3+ nanocrystals were prepared through a hydrothermal method with the help of SOD CITR and EDTA surfactants. The phase and morphology of the products were characterized by XRD and TEM, and the fluorescence performances were also recorded. The results indicated that Ca2+ ions were doped into the LaVO4:Eu3+ host lattice, impeding the aggregation of the nanocrystals and enhancing the luminescence intensity. The morphology transformation process and luminescence enhancement were systematacially investigated. The fluorescence intensity of the two selected samples could be completely quenched by Fe3+ ions without the disturbance of other ions, with the mechanism being due to the adsorption of Fe3+ ions onto the grains and a subsequent energy transfer from Eu3+ to Fe3+. Therefore, the present two Ca2+-doped LaVO4:Eu3+ samples can be applied as appropriate candidates for detecting Fe3+ ions with agility and sensitivity in aqueous solution.

Facile in situ synthesis of silver nanocomposites based on cellulosic paper for photocatalytic applications.

In this work, various photocatalysts were synthesized with an impregnation-precipitation process to in situ decorate Ag-based nanoparticles (NPs, including Ag3PO4, AgCl, Ag2O, and Ag2CO3) on the cellulosic paper. The structure and properties of the Ag-based composites were characterized by scanning electron microscopy, X-ray diffraction, transmitting electron microscopy, UV-vis diffuse reflectance spectra, and photocatalysis testing. The results showed that cellulosic paper is an efficient carrier which is feasible to grasp NPs due to the cellulosic nanofiber-network microstructure. Among the obtained samples, Ag2CO3 and AgCl NPs on cellulosic paper displayed high photocatalytic activity for the degradation of methyl orange under ultraviolet and visible light. However, photo lability of Ag2CO3 limits its recyclable. AgCl showed a better reutilization with the assistance of a surface plasmon resonance effect by Ag NPs that were grown in situ on the AgCl NPs, which formed Ag@AgCl nanocomposite structure. The photocatalytic activity of the AgCl/cellulosic paper decreased only slightly after three runs of photodegradation of methyl orange. The possible mechanism for photocatalysis was proposed. This work may provide a new method for the design of silver-based NPs/cellulosic paper nanocomposite photoreactors with favorable photocatalytic activities for industrial applications.

Preparation and performance of poly(4-vinylpyridine)-b-polysulfone-b-poly(4-vinylpyridine) triblock copolymer/polysulfone blend membrane for separation of palladium (II) from electroplating wastewaters.

In order to separate palladium (II) from electroplating wastewaters, poly(4-vinylpyridine)-b-polysulfone-b-poly(4-vinylpyridine) (P4VP-PSF-P4VP) / polysulfone blend membranes were fabricated by combining non-solvent induced phase separation, surface segregation and self-assembly of block copolymer. Amphiphilic P4VP-PSF-P4VP was used as the membrane base material, which was synthesized by introducing the functional monomer of 4-vinylpyridine (4-VP), and polysulfone as the additive. Effects of blend ratio and 4-VP content on membrane performance, such as structure, hydrophilicity, pure water flux and adsorption capacity towards Pd (II), were investigated. The membranes exhibited dense surface structure and low roughness due to surface segregation and self-assembly of P4VP-PSF-P4VP. The presence of 4-VP increased hydrophilicity and water flux of membrane, and it also provided good adsorption capacity towards Pd (II) (up to 103.1 ±â€¯5.15 mg/g). Further, the membrane was used to separate Pd (II) from simulated wastewaters during filtration. It showed good rejection ability and high selectivity towards Pd (II) in co-existence of Cu (II) and Ni (II), and selectivity coefficients of Pd/Cu and Pd/Ni are 41.9 ±â€¯1.88 and 97.8 ±â€¯4.32, respectively. In filtration process of actual electroplating wastewater, the membrane also exhibited excellent rejection performance (Pd (II) rejection reached up to 96.8 ±â€¯2.71%). Perhaps it is suitable for future practice applications.

Synthesis of Polyurethane Hydrogel and Polyurethane Thermoplastic Elastomer Composite Based Separation Membranes.

A series of polyurethane hydrogel and polyurethane thermoplastic elastomer composite based separation membranes were successfully prepared via wet phase inversion method. The morphology, chemical structure, phase transition temperature and crystallinity of the polyurethane (PU) membranes were characterized by SEM, FTIR, DSC, and XRD, respectively. The SEM observation showed that the PU membranes exhibited irregular porous structure on the surface and path of the hole was flexural and asymmetrical in cross-section. The FTIR analysis demonstrated that thermalsensitive groups and pH-sensitive components (-N(CH3)-) were incorporated into the PU network. The DSC experiment and XRD experiment showed that the regular arrangement of PU network was destroyed partly due to the introduction of polyurethane thermoplastic elastomer. The equilibrium swelling ratio (ESR) and water flux (J) for PU membranes clearly decreased and increased with functional groups and sophisticated structure of PU membranes, respectively. In addition, the permeation experiments indicated that the permeation percentage (P) of the glycine was strongly affected by the external temperature and pH value.

Transcrystallization of Isotactic Polypropylene/Bacterial Cellulose Hamburger Composite.

Isotactic polypropylene (iPP) is a commonly used thermoplastic polymer with many excellent properties. But high brittleness, especially at low temperatures, limits the use of iPP. The presence of transcrystallization of iPP makes it possible for fiber-reinforced iPP composites with higher strength. Bacterial cellulose (BC) is a kind of cellulose with great potential to be used as a new filler to reinforce iPP due to its high crystallinity, biodegradability and efficient mechanical properties. In this study, the iPP/BC hamburger composite was prepared by a simple hot press and maleic anhydride grafted polypropylene (MAPP) was used to improve the interface compatibility of iPP and BC. The polarizing microscope (POM) photograph shows that BC successfully induces the transcrystallization of iPP. The differential Scanning Calorimeter (DSC) date proves that the addition of BC could improve the thermal properties and crystallization rate of the composite. Especially, this change is more obvious of the iPP/MAPP/BC. The mechanical properties of the iPP/BC composites were greatly increased. This DSC date is higher than BC; we used BC particles to enhance the iPP in our previous research. The scanning Electron Microscope (SEM) analysis intuitively shows that the interface of the iPP/MAPP/BC is more smooth and flat than the iPP/BC. The fourier Transform infrared spectroscopy (FT-IR) analysis of the iPP/BC hamburger composites was shown that a new C=O group vibration appeared at 1743 cm-1, which indicated that the hydrogen bond structure of BC molecules was weakened and some hydroxyl groups were substituted after modification which can increase the lipophilicity of BC. These results indicated that the BC fiber can easily induce the transcrystallization of iPP, which has excellent mechanical properties. Moreover, the addition of MAPP contributes greatly to the interface compatibility of iPP and BC.

Isothermal Crystallization and Rheology Properties of Isotactic Polypropylene/Bacterial Cellulose Composite.

Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were prepared by solution mixing. Esterification modified BC (CO) and Maleic anhydride grafted polypropylene (MAPP) added as a compatibilizer was both used to improve the interfacial compatibility of the iPP/BC composites. The rheology and isothermal crystallization behavior of the composites was tested and discussed. The result shows that the complex viscosity and storage modulus of the composite significantly increase in the rule iPP, iPP/BC2, iPP/CO2, and M-iPP/BC3, which indicates that the compatibility of the composite increases as this rule. According to the isothermal crystallization kinetics result, the crystal growth mode of iPP was not affected by the addition of BC and the interfacial compatibility. The spherulite growth rate of the iPP/BC composite increases with increasing crystallization temperature. Especially, the value decreases as the same rule with the complex viscosity and storage modulus of the composite at the same isothermal crystallization temperature. These results suggest that the interface compatibility of iPP/BC composites is greatly improved and the interface compatibility of the M-iPP/BC3 is better than the iPP/CO2.

Investigation on the structural effect of lignin during the hydrogenolysis process.

Structure has a significant effect on the lignin degradation, so the investigation of structural effect on the lignin depolymerization is important and imperative. In this study, hydrogenolysis of three typical lignins with different structures, dealkaline lignin, sodium lignosulfonate and organosolv lignin, was intensively compared over the synergistic catalyst of CrCl3 and Pd/C. The effects of reaction temperature, time, hydrogen pressure and catalyst dosage on the catalytic performance of lignin species were investigated. The structure evolution of lignins during the hydrogenolysis process was also compared. The results showed that organosolv lignin was more sensitive for hydrogenolysis than others due to its high unsaturation degree and low molecular weight. Further analysis indicated that the hydrogenolysis, hydrodeoxygenation and repolymerization reactions took place and competed intensely. Wherein, the depolymerization products with unsaturated carbonyl groups were prone to repolymerize. And the methylation was helpful to stabilize the depolymerization products and suppress the further repolymerization.

Efficient and product-controlled depolymerization of lignin oriented by metal chloride cooperated with Pd/C.

An efficient lignin depolymerization process with highly controllable product distribution was presented using metal chloride (MClx) cooperated with Pd/C. The catalytic performances of MClx were investigated. The effect of reaction conditions on the lignin depolymerization and products distribution were also studied. Results showed that more than 35.4% yield of phenolic monomer including 7.8% phenols and 1.1% guaiacols could be obtained under optimized condition. And the product distribution can be efficiently controlled by the modification of the metal cation through different pathway of Lewis acid catalysis and coordination catalysis. Furthermore, the Pd/C catalyst showed an excellent recyclability, where no significant loss of the catalytic activity was exhibited after 3 runs. Moreover, the product control mechanism was proposed.