Triethylamine (TEA) gas sensors having excellent response and selectivity are in great demand to monitor the real environment. In this work, we have successfully prepared a hollow SnO microfiber by a unique sustainable biomass conversion strategy and shown that the microfiber can be used in a high-performance gas sensor. The sensor based on the hollow SnO microfiber shows a quick response/recovery toward triethylamine. The response of the hollow SnO microfiber is up to 49.5 when the concentration of TEA gas is 100 ppm. The limit of detection is as low as 2 ppm. Furthermore, the sensor has a relatively low optimal operation temperature of 270 °C, which is lower than those of many other reported sensors. The excellent sensing properties are largely attributed to the high sensitivity provided by SnO and the good permeability and conductivity of the one-dimensional hollow structure. Thus, the hollow SnO microfiber using sustainable biomass as a template is a significant strategy for a unique TEA gas sensor.
A simple seaweed biomass conversion strategy is proposed to synthesize highly porous multishelled Ni‐rich Li(NixCoyMnz)O2 hollow fibers with very low cation mixing. The low cation mixing results from the cation confinement by the novel “egg‐box” structure in the alginate template. These hollow fibers exhibit remarkable energy density, high‐rate capacity, and long‐term cycling stability when used as cathode material for Li‐ion batteries.
The polar surface of (001) wurtzite-structured MnO possesses substantial electrostatic instabilities that facilitate a wurtzite to graphene-like sheet transformation during the lithiation/delithiation process when used in battery technologies. This transformation results in cycle instability and loss of cell efficiency. In this work, we synthesized MnO hexagonal sheets (HSs) possessing abundant oxygen vacancy defects (MnO-Vo HSs) by pyrolyzing and reducing MnCO3 HSs under an atmosphere of Ar/H2. The oxygen vacancies (Vos) were generated in the reduction process and have been characterized using a range of techniques: X-ray absorption fine structure, electron-spin resonance, X-ray absorption near edge structure, Artemis modeling, and R space Feff modeling. The data arising from these analyses inform us that the introduction of one Vo defect within each O atom layer can reduce the charge density by 3.2 × 10–19 C, balancing the internal nonzero dipole moment and rendering the wurtzite structure more stable, so inhibiting the change to a graphene-like structure. Density function theory calculations demonstrate that the incorporation of Vos sites significantly improves the charge accumulation around Li atoms and increases Li+ adsorption energies (−2.720 eV). When used as an anode material for lithium ion batteries, the MnO-Vo HSs exhibit high specific capacity (1228.3 mAh g–1 at 0.1 A g–1) and excellent cell cycling stabilities (∼88.1% capacity retention after 1000 continuous charge/discharge cycles at 1.0 A g–1).
ethanol) were found to play an important role in reducing the concentration of Fe-Li antisite defects. However, the concentration of Fe-Li antisite defects reduced is still limited (higher than 0.99%), which cannot improve the rate performance of LIB efficiently. [9,10] Herein, we report on the synthesis of an ideal crystalline LFP/carbon hybrid microtube (LFP/CMT) with the lowest Fe-Li antisite defects reported (<0.3%) to boost the lithium ion storage. The key concept for suppressing the Fe-Li antisite defects is through the use of the strong chelation interaction with Fe 3+ and absorbs interaction with Li + of alginate. This is able to efficiently control the prior occupancy of Fe at the beginning of the crystal formation, thus reduce the concentration of Fe-Li antisite defects in subsequent pyrolysis process and produce well-crystallized LFP nanoparticles (NPs). Meantime, the carbohydrate framework of alginate fiber was converted to highly porous carbonaceous hybrid microtube (CMT) after pyrolysis in nitrogen (N 2 ) atmosphere, in which the LFP NPs with low Fe-Li antisite defects are embedded. This can highly enhance the electrical conductivity of the LFP NPs. As a consequence, the LFP/CMT displays superior discharge capacity of 165 mAh g −1 at 0.5 C, excellent capacity retention of 91% after 1000 cycle numbers, and outstanding rate capacity of 99.7 mAh g −1 at 100 C.Protonated alginate fiber [11][12][13] was used to prepare the LFP electrodes with low Fe-Li antisite defects (see details in Supporting Information). The protonated alginate fiber was soaked into the mixed aqueous solutions of ferric nitrate nonahydrate (Fe(NO 3 ) 3 ·9H 2 O), ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ), and lithium nitrate (LiNO 3 ) to form yellow Li-Fe-P-alginate fibers. The reduction of Fe-Li antisite defects is achieved by unique "egg-box" structure in alginate macromolecule. As shown in Scheme 1b, the Fe 3+ was immobilized into "egg-box" via coordination with G blocks in alginate, and the PO 4 3− was adsorbed by the Fe 3+ cations. As described in Figure S1 of the Supporting Information, the diffraction peak at 2θ = 21.18° was observed from the X-ray diffraction (XRD) pattern of Fe-P-alginate fiber, ascribed to a typical "egg-box" structure in G-rich Fe-alginate junction zones. [14,15] However, the monovalent Li + ions can only be adsorbed by the carboxyl (M block) via the electrostatic force. [16,17] The diffraction peaks at 2θ = 38.05° and 44.22° are ascribed to Fe-rich Li-alginate junction zones (see Figure S1, Supporting Information). [16] Obviously, the unexpected Fe-Li mixing could be avoided at the initial ion-exchange stage.The Li-Fe-P-alginate fibers were calcined at different temperatures (350-850 °C) in N 2 atmosphere to obtain a series of porous LFP/CMT with low concentration of Fe-Li antisite Olive structured LiFePO 4 (LFP) is a good candidate for lithiumion battery (LIB) cathode material due to its high theoretical capacity of 170 mAh g −1 , high electrochemical potential, good thermal stability, environmenta...
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