Tao Duan

Perovskite chromate doped with titanium for direct carbon dioxide electrolysis

A composite cathode based on lanthanum chromate has uncovered tremendous potential for direct high temperature electrolysis. Unfortunately, a major setback of insufficient electrocatalytic activity limits the efficient carbon dioxide electrolysis. In this paper, catalytically active Ti is doped to partially replace Cr at the B-site in perovskite La0.75Sr0.25Cr0.5−xFe0.5TixO3−δ (LSCrFT, x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) to improve the polarization and electrocatalytic property of the cathode materials of the solid oxide electrolyzer. The transition of the dominant mechanism from p-type conduction to n-type conduction is observed for the LSCrFT cathode with the Ti doping level at x = 0.3. The doping of Ti in LSCrFT largely improves the electrode activity and therefore reduces electrode polarization resistance. A high-temperature CO2 electrolysis test demonstrates that the Faraday efficiencies of LSCrFT (x = 0.1) cathodes are enhanced by approximately 30% in contrast to bare LSCrF cathodes at 800 °C.

A biomass carbon mass coated with modified TiO2 nanotube/graphene for photocatalysis

Powdered modified TiO2 materials are commonly used for photocatalysis. They are easily dispersed in solution but difficult to recycle. In addition, the low light transmission and lack of oxygen in solution also cause a decrease of the photocatalytic efficiency for practical applications. Here we prepare a low-density circular slice which can be suspended on the surface of an aqueous solution and can be used to enrich methylene blue easily. The body of the circular slice is a kind of biomass carbon derived from fungus while the surface of the circular slice is coated with Fe/N co-doped TiO2 nanotubes and a N-doped graphene composite. The advantages are that the circular slice cannot only be convenient to recycle, but also be easy to receive light and oxygen. According to the photocatalytic activity test, the floatable material consisting of Fe/N-TNTs/NG and fungus shows superb performance on the degradation of methylene blue under simulated solar irradiation, which makes it a promising photocatalytic material.

Effects of Montmorillonite on the Mineralization and Cementing Properties of Microbiologically Induced Calcium Carbonate

Carbonate mineralization microbe is a microorganism capable of decomposing the substrate in the metabolic process to produce the carbonate, which then forms calcium carbonate with calcium ions. By taking advantage of this process, contaminative uranium tailings can transform to solid cement, where calcium carbonate plays the role of a binder. In this paper, we have studied the morphology of mineralized crystals by controlling the mineralization time and adding different concentrations of montmorillonite (MMT). At the same time, we also studied the effect of carbonate mineralized cementation uranium tailings by controlling the amount of MMT. The results showed that MMT can regulate the crystal morphology of calcium carbonate. What is more, MMT can balance the acidity and ions in the uranium tailings; it also can reduce the toxicity of uranium ions on microorganisms. In addition, MMT filling in the gap between the uranium tailings made the cement body more stable. When the amount of MMT is 6%, the maximum strength of the cement body reached 2.18u2009MPa, which increased by 47.66% compared with that the sample without MMT. Therefore, it is reasonable and feasible to use the MMT to regulate the biocalcium carbonate cemented uranium tailings.

Bioconcentration of organic dyes via fungal hyphae and their derived carbon fibers for supercapacitors

Heteroatom doping can change the electrochemical properties of carbon materials, but the simple, cheap and environmentally friendly preparation of these materials still remains a challenge. Herein, we have reported a new general strategy to fabricate heteroatom-doped carbon fiber materials based on the bioconcentration of different toxic organic dyes via fungal hyphae. The doped carbon fibers had a high content of heteroatoms and a three-dimensional network structure, exhibiting great potential as electrode materials for supercapacitors. Among these products, the N–S doped carbon fiber prepared by bioconcentration of methylene blue had the highest specific capacitance of 235 F g−1 at 1 A g−1 and good rate capability (72.8% retention from 1 A g−1 to 20 A g−1). This strategy can turn toxic waste into valuable materials, converting trash to treasure in the most literal sense; this bioconcentration method is green, general, low-cost and suitable for the preparation of fungal hyphae heteroatom-doped carbon fiber materials from different heteroatom precursors.

Silver nanoparticles incorporated konjac glucomannan-montmorillonite nacre-like composite films for antibacterial applications

Artificial nacre-like konjac glucomannan-Montmorillonite (KGM-MTM) composite films with brick and mortar microstructures have been fabricated based on using KGM-MTM hybrid nanosheets as building blocks. In the designed fabrication procedure, we assembled hybrid building blocks with a thin layer of KGM coating on the MTM nanosheets to form KGM-MTM composite film via vacuum filtration. The nacre-like microstructures enhanced the light transmission performance and mechanical properties (Tensile strength: 116u202fMPa) of KGM-MTM composite films. Additionally, Ag nanoparticles (Ag NPs) can be incorporated into the layered structures of KGM-MTM composite films via an in situ reduced method. It was found that KGM-MTM-Ag composite films significantly suppress bacterial growth, which makes them potentially applicable as antimicrobial films in the biomedical field.

One step hydrothermal synthesis of 3D CoS2@MoS2-NG for high performance supercapacitors

A three-dimensional (3D) MoS2 coated CoS2-nitrogen doped graphene (NG) (CoS2@MoS2-NG) hybrid has been synthesized by a one step hydrothermal method as supercapacitor (SC) electrode material for the first time. Such a composite consists of NG embedded with stacked CoS2@MoS2 sheets. With a 3D skeleton, it prevents the agglomeration of CoS2@MoS2 nanoparticles, resulting in sound conductivity, rich porous structures and a large surface area. The results indicate that CoS2@MoS2-NG has higher specific capacitance (198 F g-1 at 1 A g-1), better rate performance (with about 56.57% from 1 to 16 A g-1) and an improved cycle stability (with about 96.97% after 1000 cycles). It is an ideal candidate for SC electrode materials.

Natural polymer konjac glucomannan mediated assembly of graphene oxide as versatile sponges for water pollution control

Three-dimensional network structure of konjac glucomannan/graphene oxide (KGM/GO) sponges was successfully prepared by ice template method. The KGM/GO sponges was rich in functional groups, negatively charged under pH 2 to 10. Batch adsorption experiment was conducted to investigate the adsorption performance of the as-prepared KGM/GO sponges for organic dye (malachite green (MG)) and radionuclide (uranium U(Ⅵ)). The results showed that the maximum adsorption capacities of KGM/GO sponges were 266.97, 189.96 mg/g for U(Ⅵ) and MG, respectively. Moreover, the KGM/GO sponges exhibited an excellent selectivity for capturing U(Ⅵ) in multi-ion system. The adsorption process was fitted better to pseudo-second order model, while adsorption isotherms for these pollutants were well matched up to Langmuir models. In addition, KGM/GO sponges can be easily separated from the aqueous solution and could be effectively reused for 5 times without obvious loss in adsorption performance. The advantages of eco-friendliness, low cost, simple preparation process, controllable shape and size, as well as high adsorption capacities for MG and U(Ⅵ), suggested that KGM/GO sponges promising in water pollution control.