5 research outputs found

    Carbon Dioxide Capturing by Nitrogen-Doping Microporous Carbon

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    Nitrogen-containing microprous carbon was successfully synthesized by using phloroglucinol and glutaraldehyde as the carbon source and hydrolyzed silk as the nitrogen source. The porous structures and surface chemical compositions of microporous carbon were analyzed and characterized by nitrogen adsorption isotherms, thermogravimetric analysis, Fourier transform infrared spectrum and scanning electron microscope images. The resultant porous carbons had a microporous structure, and the pore size distribution was 0.7–2.0 nm. Phenolic formaldehyde with silk was pyrolyzed and decomposed to condense a cross-linking structure between 230 and 650 °C. The nitrogen-containing groups from silk decomposition were incorporated into a carbon matrix during the carbonization process. The microporous carbon showed good regeneration performance and high adsorption capacities of CO<sub>2</sub> due to its nitrogen-containing groups and developed a micropore structure. Under dynamic conditions, CO<sub>2</sub> could be finely separated from a mixture of CO<sub>2</sub>, N<sub>2</sub> and CH<sub>4</sub> with microporous carbon, which displayed potential application for CO<sub>2</sub> capture

    Fe<sub>3</sub>O<sub>4</sub>@Carbon Nanosheets for All-Solid-State Supercapacitor Electrodes

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    Fe<sub>3</sub>O<sub>4</sub>@carbon nanosheet composites were synthesized using ammonium ferric citrate as the Fe<sub>3</sub>O<sub>4</sub>/carbon precursor and graphene oxide as the structure-directing agent under a hydrothermal process. The surface chemical compositions, pore structures, and morphology of the composite were analyzed and characterized by nitrogen adsorption isotherms, TG analysis, FT-IR, X-ray photoelectron energy spectrum, transmission electron microscopy, and scanning electron microscopy. The composites showed excellent specific capacitance of 586 F/g, 340 F/g at 0.5 A/g and 10 A/g. The all-solid-state asymmetric supercapacitor device assembled using carbon nanosheets in situ embedded Fe<sub>3</sub>O<sub>4</sub> composite and porous carbon showed a largest energy density of 18.3 Wh/kg at power density of 351 W/kg in KOH/PVA gel electrolyte. The synergism of high special surface to volume ratio, mesoporous structure, graphene-based conduction paths, and Fe<sub>3</sub>O<sub>4</sub> nanoparticles provided a high surface area of ion-accessibility, high electric conductivity, and the utmost utilization of Fe<sub>3</sub>O<sub>4</sub> and resulted in excellent specific capacitance, outstanding rate capability and cycling life as all-solid-state supercapacitor electrodes

    Mechanistic Study of Codoped Titania with Nonmetal and Metal Ions: A Case of C + Mo Codoped TiO<sub>2</sub>

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    To study the mechanism of metal- and nonmetal-ion-doped TiO<sub>2</sub>, TiO<sub>2</sub> codoped with carbon and molybdenum prepared by a hydrothermal method following calcination post-treatment is chosen as the study object. The prepared samples are characterized by X-ray diffractmeter, Raman spectroscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller measurement. It is found that the doped carbon exists in the form of deposited carbonaceous species on the surface of TiO<sub>2</sub>, and molybdenum substitutes for titanium in the lattice and exists as the Mo<sup>6+</sup> state. All the prepared samples have comparable large surface areas. The photocatalytic activities are tested by degradation of rhodamine-B and acetone under visible light irradiation. The results show that the codoped sample has the best performance in the degradation of both RhB and acetone. Briefly, the enhanced photocatalytic activity of codoped TiO<sub>2</sub> is the synergistic effect of C and Mo. Mo substitutes in the Ti site in the lattice for the formation of the doping energy level, and C exists as carbonaceous species on the surface of the TiO<sub>2</sub>, which can absorb visible light. The synergetic effects of C and Mo not only enhance the adsorption of visible light but also promote the separation of photogenerated electrons and holes, which consequently contribute to the best photodegradation efficiency of organic pollutants under visible-light irradiation. UV–vis diffuse reflectance spectra and photoluminescence spectra of the prepared samples and fluorescence of terephthalic acid for the detection of hydroxide radical are employed to verify the proposed mechanism

    Self-Assembly of Three-Dimensional SrTiO<sub>3</sub> Microscale Superstructures and Their Photonic Effect

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    3D SrTiO<sub>3</sub> microscale superstructures (STOMSs) have been prepared <i>via</i> hydrothermal synthesis and multiple (five times) crystallization process. Branches and trunks on STOMSs show perfect corn-like structures, and each side of the trunks could be considered as grating-analogous structures. These well-ordered trunks along with gratings constitute 3D hybrid microstructures that contribute to light diffraction, and the colorful photonic effects of light diffraction are thought to be due to refractive index modulations in three dimensions. The colors of STOMSs can be tuned from yellow to cyan by changing the growth cycle. This special optical performance could broaden the application scope of SrTiO<sub>3</sub>

    Unique Three-Dimensional InP Nanopore Arrays for Improved Photoelectrochemical Hydrogen Production

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    Ordered three-dimensional (3D) nanostructure arrays hold promise for high-performance energy harvesting and storage devices. Here, we report the fabrication of InP nanopore arrays (NPs) in unique 3D architectures with excellent light trapping characteristic and large surface areas for use as highly active photoelectrodes in photoelectrochemical (PEC) hydrogen evolution devices. The ordered 3D NPs were scalably synthesized by a facile two-step etching process of (1) anodic etching of InP in neutral 3 M NaCl electrolytes to realize nanoporous structures and (2) wet chemical etching in HCl/H<sub>3</sub>PO<sub>4</sub> (volume ratio of 1:3) solutions for removing the remaining top irregular layer. Importantly, we demonstrated that the use of neutral electrolyte of NaCl instead of other solutions, such as HCl, in anodic etching of InP can significantly passivate the surface states of 3D NPs. As a result, the maximum photoconversion efficiency obtained with ∼15.7 μm thick 3D NPs was 0.95%, which was 7.3 and 1.4 times higher than that of planar and 2D NPs. Electrochemical impedance spectroscopy and photoluminescence analyses further clarified that the improved PEC performance was attributed to the enhanced charge transfer across 3D NPs/electrolyte interfaces, the improved charge separation at 3D NPs/electrolyte junction, and the increased PEC active surface areas with our unique 3D NP arrays