查看更多>>摘要：The sluggish reaction kinetics, polysulfide shuttling and low-efficiently use of sulfur largely imped the rate performance and energy density of lithium-sulfur batteries. To overcome the bottleneck, we used 1D TEMPO-oxidized cellulose nanofibers (T-CNF) and 2D rGO nanosheets as "rebar" and "cement" to construct a tough framework, and the monolayer MXene (m-MXene) was uniformly wrapped on the framework forming a MXene-coated three-dimensional aerogel (MCG aerogel) with high ionic and electronic conductivity. It is worth mentioning that the negatively charged groups of MXene can not only accelerate the ion diffusion rate and the conversion process of polysulfides by anchoring polysulfides through strong adsorption sites, but also construct an ion selective layer to inhibit the shuttle effect of polysulfides. Moreover, the T-CNF-enhanced three-dimensional structure alleviates the negative impact of sulfur volume expansion during the charging and discharging process, making it possible to directly used the aerogel as self-supporting electrodes without any binder. Therefore, the T-CNF/rGO hybrid aerogels with monolayer MXene coating as cathode materials for Lithium-sulfur batteries exhibit high discharge capacity of 1470 mA h g~(-1) at 0.1 C and improved rate capability of 744 mA h g~(-1) at 5 C. The high-strength framework structure with uniform surface sulfur-anchor coating design strategy offers a new angle of regulating the diffusion kinetic rate of lithium-sulfur batteries.
查看更多>>摘要：Here, we report a robust method for fabricating ZnO nanorod arrays with arbitrary patterns on glass substrate for device integration applications. Photolithography patterned non-transparent Zn film is used as growth sites for ZnO nanorods in the hydrothermal reactions for facile and reproducible fabrication. Patterns including lines, dots, texts, and logos have been demonstrated and the dimension of ZnO nanorods are tunable. The semi-transparent ZnO nanorod/glass shows increased light transmission when immersed in water, which is an advantage when integrate into devices requiring optical imaging and sensing. For proof-of-concept purpose, surface-enhanced Raman scattering sensors based on Ag coated ZnO nanorods with back observation configuration are demonstrated and show high sensitivity.
查看更多>>摘要：Metal oxide supports have attracted much attention for improving the performance and durability of polymer electrolyte fuel cells. In this study, niobium-doped tin oxide (NTO) nanoparticles with a network structure were synthesized and Pt catalysts deposited on them using a flame aerosol technology. Because the flame method involves a variety of particle formation processes, which depend on the type of raw material and combustion method used, the effect of these processes on the particle structure, of the flame-made Pt/NTO was evaluated. When Pt/NTO nanoparticles were prepared by flame-assisted spray pyrolysis (FASP) using an inorganic raw material (metal chloride) with lower combustion enthalpy, the precursor liquid burned incompletely and Pt aggregation was observed. However, when flame spray pyrolysis (FSP) using a combustible precursor solution was used, the precursor rapidly evaporated in spray flames, and NTO with uniformly dispersed Pt was synthesized through gas-to-particle conversion. The electrochemical surface area and mass activity values of 5.44 wt% Pt-loaded NTO particles prepared by FSP were 48.2 m~2 g~(-1) Pt and 338 mA mg~(-1) Pt, respectively. Flame aerosol synthesis of supported metal catalysts can be widely used as a dry one-step process that does not involve any complicated post-treatment. The two types of noble metal loading processes revealed in this study provide important insights for determining particle design guidelines for in-situ production of supported metal catalysts in flames.
查看更多>>摘要：White light-emitting diodes (LEDs) are great candidates for general lighting. Phosphors have commonly been used for the color conversion layers of white LEDs; however, they backscatter more than half of the down-converted light, which is lost within the device, thus degrading the overall performance. In this study, we propose and demonstrate white LEDs with improved efficiency enabled by the intimate integration of Ag@SiO_2-supported blue InGaN/GaN nanorod LEDs together with green- and red-emitting perovskite nanocrystal (PNC) films as color conversion layers. The photoluminescence (PL) intensity of the blue LEDs (BLEDs) was significantly enhanced owing to the localized surface plasmon (LSP) effect of Ag@SiO_2 nano-particles. In addition, the perovskite PL intensity was improved by the high-power BLED backlight. The resulting PL intensity of the Ag@SiO_2 nanoparticle-embedded nanorod white LED was 62% greater than that of a planar white LED.
查看更多>>摘要：The removal of low concentration pollutants in water is very important for environmental remediation. Herein, MCr-LDHs/BiOBr (M = Zn, Ni, Cu) heterojunction nanocomposites were fabricated by a facile rapid crystallization method. Visible-light responsive heterojunctions could be formed efficiently at the intimately contacted interface between BiOBr nano-crystallites and LDHs nano-flakes, which showed higher photocatalytic degradation activities of cationic, anionic, and electrically neutral organic pollutants than pristine LDHs and BiOBr. Degradation of 99.5% Rhodamine B, 80% methyl orange, and 97% bisphenol A could be achieved by the composite catalysts under visible-light irradiation in 15 min, 60 min, and 40 min, respectively, and cycling test proved the good reusability of composite catalysts as well. Benefitting from superior adsorption properties for ionic organic pollutants, and effective separation and transition of photogenerated holes and electrons, the MCr-LDH/BiOBr composite catalysts exhibit wide applicability for removal of various organic pollutants in water and have potential application prospects in the future.
查看更多>>摘要：Exploring comwposite nanomaterials with novel and stable nanostructures is of great importance for high performance supercapacitors (SCs). Herein, the nanosheet-like XMoO_4 (X=Ni, Co) were uniformly grown on the carbon submicrofibers (CMFs) by a facile hydrothermal route. The NiMoO_4 @CMFs exhibits higher specific capacitance of 1485.53 F g~(-1) and better cycling stability with 87.6% retention after 3000 cycles at 1 A g~(-1) than that of CoMoO_4 @CMFs (1407.1 F g~(-1) 80.6% retention after 3000 cycles at 1 A g~(-1)). To further improve the electrochemical performance of NiMoO_4 @CMFs, the hollow porous carbon submicrofibers (HPCMFs) were designed and used as a substrate for NiMoO_4. Benefiting from the hollow porous structure, the HPCMFs can provide large specific surface area for electrolyte permeating and supply more ion channels in the charge-discharge process. Therefore, the NiMoO_4 HPCMFs exhibits a high specific capacitance of 1600.0 F g~(-1) at 1 A g~(-1) and good cycling stability of 90.7% retention after 3000 cycles. The all-solid stated symmetric supercapacitors (ASSCs) were directly assembled by using NiMoO_4 @HPCMFs as electrode without any additives, which shows good flexibility and a high energy density of 55.33 Wh kg~(-1) at a power density of 999.89 W kg~(-1). Moreover, five series ASSCs can light 'DHU' logo, indicating potential application prospect in wearable electronics.
NSTL
Elsevier