Qinze Liu

LiFePO4/NaFe3V9O19/porous glass nanocomposite cathodes for Li+/Na+ mixed-ion batteries

The discovery and optimisation of high performance cathode materials are critical to future breakthroughs for next-generation rechargeable batteries. LiFePO4 (LFP)/NaFe3V9O19 (NFV)/Na2O–FeO–V2O3–P2O5–biocarbon (NFVPB) porous glass nanocomposites (LFP/NFV/NFVPB) offer new possibilities for Li+/Na+ mixed-ion batteries with high-rate capability and high discharge voltage plateaus. Here we have successfully synthesized these nanocomposites via self-assembly of adenosine disodium triphosphate (Na2ATP) biotemplates and a carbon thermal reduction method. As a novel cathode material, LFP/NFV/NFVPB delivers a reversible capacity of 202.8 mA h g−1 at 0.1C in the Li+/Na+ mixed-ion cell with the electrochemically active redox reactions of Fe2+/Fe3+ and V3+/V4+, which is far higher than the theoretical capacity of LiFePO4 (170 mA h g−1). The cell exhibits two high voltage plateaus with well-defined discharge voltage near 3.4 and 3.7 volts, and a coulombic efficiency of approximately 90 percent. Because the low-energy nonequilibrium paths of the fast phase transformation process in LFP/NFV composite nanoparticles can improve the high-rate performance, the cell still exhibits a higher specific capacity of about 100.4 mA h g−1 at 10C. These results are attributed to the nanocomposite structure of LiFePO4 and NaFe3V9O19 and better percolation of electrochemically active glass with a hierarchical pore structure. This work will contribute to the development of Li+/Na+ mixed-ion batteries.

Adsorption–reduction of chromium(VI) from aqueous solution by phenol–formaldehyde resin microspheres

A novel adsorbent of phenol–formaldehyde resin (PF) microspheres was prepared at a low temperature, and had an excellent performance for the adsorption–reduction of Cr(VI). The microspheres were characterized by transmission electron microscope (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS). The effects of contact time, pH value and initial concentration, adsorbent dosage and temperature were studied by batch mode. The results showed that the adsorption process fitted a pseudo-second-order model and a Langmuir isotherm model very well, and an intra-particle diffusion model gave three stages in the whole process. Thermodynamic constant values (ΔH° > 0, ΔS° > 0, ΔG° < 0) indicated that the adsorption process was endothermic and spontaneous. The maximum adsorption capacity of Cr(VI) on the adsorbent reached 280.9 mg g−1 at 303 K. The PF microspheres could be applied to Cr(VI)–water treatment with the reduction and adsorption of the heavy metal ion.

Removal of Cu(II) from aqueous solution using synthetic poly(catechol-diethylenetriamine-p-phenylenediamine) particles

A novel poly(catechol-diethylenetriamine-pphenylenediamine)(PCEA) adsorbent was synthesized in methanol, with chelating groups supplied by catechol and diethylenetriamine, which showed a strong removal performance and efficient adsorption toward Cu(II) ions in aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Besides, factors such as adsorbent dosage, pH, initial ionic and metal concentrations, contact time, and temperature on the adsorption of Cu(II) were studied. The data revealed that the adsorption followed a pseudo-second order kinetic model and the adsorption rate was influenced by the intra-particle diffusion. Furthermore, the adsorption process followed the Langmuir isotherm model, and the maximum adsorption capacity (Qm) was 44.2mg/g at 298K in simulated wastewater. The value of ΔG (kJ/mol) and ΔH (kJ/mol) also demonstrated that the adsorption process was spontaneous and endothermic. Studies revealed that PCEA particles were powerful and stable for the removal of Cu(II) in water, and it could be directly applied to the Cu(II)-contaminated water.

Effects of morphology on the electrochemical performances of Li3V2(PO4)3 cathode material for lithium ion batteries

Lithium ion batteries (LIBs) are considered as one of the most successful energy storage systems for a wide range of modern applications. Cathode materials, as one of the most important components of LIBs, play a critical role in determining the performances of LIBs. Monoclinic Li3V2(PO4)3 (LVP) is one of the cathode materials with most potential for LIBs because of its high theoretical capacity, high operating voltage and safety performance. However, the intrinsically low electronic and ionic conductivity of LVP limits its development in large-scale application. Various methods such as carbon coating, cation doping and reducing the particle size have usually been used to improve the electrochemical performances of LVP. Besides, the design and optimization of LVP morphology are also effective approaches to improve the electrochemical performances of LVP. In this review, we discuss the development of morphology modifications such as porous structure, spherical structure, core–shell structure, rod-like structure, plate-like structure, nanofiber structure and flower-like structure in recent years and study the effects of various morphologies on the electrochemical performances of LVP.

Design and fabrication of a novel superhydrophobic surface based on a copolymer of styrene and bisphenol A diglycidyl ether monoacrylate

The copolymer of styrene and bisphenol A diglycidyl ether monoacrylate (PS-co-AADGEBA) was synthesized by three steps from raw materials, and then it was used to fabricate a superhydrophobic surface via a phase separation method. In particular the superhydrophobic surface not only exhibits superhydrophobicity towards water and corrosive liquids, including acidic and basic solutions, but also shows good transparency, improved robustness and excellent aging resistance. Furthermore, the PS-co-AADGEBA was also successfully grafted onto the surface of amino-functionalized hollow silica nanospheres (HSNs-NH2), then a (PS-co-AADGEBA)-g-(HSNs-NH2) nanocomposite superhydrophobic surface was prepared. The obtained surfaces are promising materials for numerous potential application fields, including electronics, biomedical, martial and defense-related areas.

Fabricating three-dimensional mesoporous carbon network-coated LiFePO4/Fe nanospheres using thermal conversion of alginate-biomass

The lack of cathode materials with high energy density has become a bottleneck for the development of low-cost lithium-ion batteries (LIBs). Here, we develop three-dimensional mesoporous carbon network (3DMCN)-coated LiFePO4/Fe nanospheres (3DMCN-LFP/Fe-NSs) for tackling this problem. This new nanocomposite cathode is synthesized by using thermal conversion of natural alginate (ALG) biomass. In the heat-treated process, an ALG hydrogel with an “egg-box” structure was transformed into unique 3DMCN, while some of the iron ions were reduced to iron metal. The 3DMCN and Fe metal coating not only reduces the anisotropy and grain size of LiFePO4, but also enhances its electron conductivity and lithium ion diffusion coefficient. This makes this specially designed nanocomposite give a remarkable synergistic effect for both lithium storage and transfer kinetics. After 256 cycles the discharge capacity (173 mA h g−1) was still higher than the theoretical capacity of LiFePO4, and its capacity retention rate is 99%. Even at a high current rate of 10C, the discharge energy density is still 6.2 times that of commercial LiFePO4. More importantly, this nanocomposite is created through a simple and cost-effective approach. This work also opens a new vista for applying renewable biomass conversion technology to develop superior LIBs.

Fabrication of hierarchical hollow silica/silver/silica/titania composite particles

Hierarchical composite particles with hollow structure were fabricated in this work. The composite particles were composed of guest particles and host ones, which were achieved by Stöber method, and a raspberry-like morphology was produced by the “anchoring” of guest particles on the surface of host ones. Moreover, the hollow structure was obtained by template-assisted approach. The raspberry-like morphology and hollow structure of composite particles were confirmed by scanning electron microscopy and transmission electron microscopy. As multiple distinct functional components were integrated into the raspberry-like particles, the obtained composite particles exhibited enhanced photocatalytic activity under visible light irradiation. The rate of degradation of the as-prepared composite particles was ca. 13 times faster than that of pure TiO2 under visible light irradiation. Furthermore, a brief photocatalytic mechanism was presented. The composite particles, combining hierarchical morphology and hollow structure, exhibit promising potential in self-cleaning and nanoreactor areas.Graphical Abstract

Green synthesis of tannin-hexamethylendiamine based adsorbents for efficient removal of Cr(VI)

Newly developed adsorbents, poly(tannin-hexamethylendiamine) (PTHA), were fabricated by varying the mole ratio of tannin (TA) and hexamethylendiamine (HA) under one-pot reaction. The specific forming process of the adsorbent which had undergone the transition from hydrogen bonds to covalent bonds was subsequently explored. Based on the efficiency of Cr(VI) removal from aqueous solution over all prepared adsorbents, the PTHA-4 (mole ratio of TA/HA = 1:12.5) exhibited an excellent adsorption behavior. Adsorption experiments affected by contact time and ionic strength have been conducted successively by PTHA-4, and the equilibrium was reached at 24 h. The kinetic data revealed that the adsorption was good agreement with pseudo-second order model and needed to undergo the rate-controlling step. The maximum adsorption capacity was 283.29 mg/g at 30 °C, relying on the isothermal curve suitably described by Langmuir model. Furthermore, toxic Cr(VI) had been reduced to the low toxic Cr(III) during adsorption process. The structures and adsorption performance of adsorbent were confirmed by means of SEM, FT-IR, XPS etc. Thus, the cheap-sustainable adsorbents have a superior feature for Cr(VI)-wastewater purification in future.

Facile synthesis of a superhydrophobic surface with modified hollow silica nanoparticles

We herein report a simple and effective method to fabricate superhydrophobic coatings by grafting polystyrene (PS) onto the vinyltriethoxysilane modified hollow silica nanoparticles (HSNs) using free radical polymerization. The resulting products were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM) and transmission electron microscopy, confirming that the PS successfully grafted onto the vinyl-modified HSNs via a covalent bond. The morphological structure of HSN film, investigated by SEM, showed a characteristic rough structure. Surface wetting properties of the HSN films were evaluated by measuring the water contact angle and the sliding angle using a contact angle goniometer, which were measured to be 158° and 6°, respectively. Moreover, the classic and the modified Cassie–Baxter relations were applied on the HSN films to verify the superhydrophobic performance.