Search

Up to now, high energy density batteries can be easily achieved by using alloys or conversion materials with high theoretical capacities (such as silicon-based and tin-based materials). However, these anode materials tend to sacrifice power densities while maintaining high energy densities. Herein, a sandwich-like C@SnS@TiO2anode with both high capacity and high power is designed by controlling a close integration between interfacial layers. The volume expansion of the middle layer of the SnS in the C@SnS@TiO2anode is greatly constrained by a synergetic interaction of the TiO2core and the carbon shell. From the results of the real-time dynamic evolution of electrode thickness during charging and discharging processes, the sandwich-like C@0.5SnS@TiO2has a max expansion rate of 11.5% in the first lithiation, which is much lower than that of pristine SnS (89.2%), and the expansion of C@0.5SnS@TiO2is basically reversible in the following charging/discharging processes. As a result, the sandwich-like C@0.5SnS@TiO2anode delivers a stable capacity of 660mAh g–1at 50 mA g–1and manifests an excellent rate capability, with a capacity of 357.2 mAh g–1at 5A g–1and a recovery ability of nearly 100%. In addition, it exhibits an outstanding long lifespan, retaining 95.6% capacity after 2500 cycles at 1A g–1. This work presents a durable tin-based anode with moderate capacity for high-energy batteries and offers some ideas for the delicate study of materials with severe expansion during circulation.

Alkali metals generated during waste incineration in power stations are not conducive to the control of nitrogen oxide (NOx) emission. Hence, improved selective catalytic reduction of NOxwith ammonia (NH3-SCR) in the presence of alkali metals is a major issue for practical NOxremoval. In this work, we developed a novel TiO2-decorated acid-treated MnOxoctahedral molecular sieve (OMS-5(H)@TiO2) catalyst with improved alkali-resistant NOxreduction at low temperature, and the dual promotional effects of OMS-5(H)@TiO2catalysts were clarified. It was found that the special structure of the acid-treated MnOxoctahedral molecular sieve (OMS-5(H)) was responsible for the trapping of alkali metals and high deNOxactivity at low temperature. Subsequently, the decoration by TiO2further improved the redox properties by accelerating the high ratio of Mn4+and Oαon the surface of the highly active (OMS-5(H)@TiO2) catalyst. Moreover, a thorough mechanism study via in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTs) demonstrated that the acid treatment led to remarkable increment of acid sites, which enabled the catalyst to resist alkali metals in the form of ion exchange. Meanwhile, the decoration of TiO2further increased the strength of the Lewis acid sites, assisting more active intermediate species to effectively take part in the deNOxreaction. Besides, a “fast SCR” process was observed to certify that the decoration of TiO2promoted the improvement of low-temperature activity in the presence of alkali metals. The dual effects combining OMS-5(H) with TiO2decoration in terms of alkali metal resistance and high catalytic activity at low temperature proved that the high-performance deNOxcatalyst was successfully developed in this work. The work paves a way for the development of superior low-temperature SCR catalysts with improved NOxreduction efficiency in the presence of alkali metals.

Lithium anodes suffer from severe safety problems in liquid electrolyte systems that result from an unstable Li plating/stripping process and Li dendrite growth, leading to rapid degradation of Li metal batteries. A polyethylene (PE)-supported gel polymer electrolyte (GPE) with excellent electrolyte uptake/retention capability was simply prepared in this paper by the construction of cross-linked polymer networks (PNs) on the surface of a poly(ethylenimine)-primed PE separator to stabilize the lithium anode. The highly delocalized negative charge of p-styrene sulfonate groups on PNs plays a role in regulating the Li+and anion transport, giving rise to a high Li+transference number. This GPE extended the electrochemical stability to 4.8 V and improved the stability of interface between the electrolyte and lithium metal anode (reduced overpotential and suppressed lithium dendrites) during storage and repeated lithium plating/stripping cycling. The Li metal anode-based battery employing this GPE exhibits excellent cycling stability and C-rate capability.

Balancing the size of the primary Si unit and void space is considered to be an effective approach for developing high performance silicon-based anode materials and is vital to create a lithium ion battery with high energy density. We herein have demonstrated the facile fabrication of coralloid-like nanostructured silicon composites (c-nSi/SiOx@Cy) via sulfuric acid etching the Al60Si40alloy, followed by a surface growth carbon layer approach. The HRTEM images of pristine and cycled c-nSi/SiOx@Cy show that abundant nanoscale internal pores and the continuous conductive carbon layer effectively avoid the pulverization and agglomeration of Si units during multiple cycles. It is interesting that the c-nSi/SiOx@C4.0anode exhibits a high initial Coulombic efficiency of 85.53%, and typical specific capacity of over 850 mAh g–1after deep 500 cycles at a current density of 1 A g–1. This work offers a facile strategy to create silicon-based anodes consisting of highly dispersed primary nano-Si units.

The composite of tungsten-doped SnO2and reduced graphene oxide was synthesized through a simple one-pot hydrothermal method. According to the structural characterization of the composite, tungsten ions were doped in the unit cells of tin dioxide rather than simply attaching to the surface. Tungsten-doped SnO2was in situ grown on the surface of graphene sheet to form a three-dimensional conductive network that enhanced the electron transportation and lithium-ion diffusion effectively. The issues of SnO2agglomeration and volume expansion could be also avoided because the tungsten-doped SnO2nanoparticles were homogeneously distributed on a graphene sheet. As a result, the nanocomposite electrodes of tungsten-doped SnO2and reduced graphene oxide exhibited an excellent long-term cycling performance. The residual capacity was still as high as 1100 mA h g–1at 0.1 A g–1after 100 cycles. It still remained at 776 mA h g–1after 2000 cycles at the current density of 1A g–1.

The pores of dodecahedron-like carbon frameworks derived from metal–organic frameworks (MOFs) were in situexpanded via a surfactant-template strategy, which were originally demonstrated to enhance capacitive deionization (CDI). The dodecahedron-like carbon frameworks were obtained through carbonization of zeolitic imidazolate framework-8 (ZIF-8) using the cetyltrimethylammonium bromide as a supramolecular template. It is found that the dodecahedron-like carbon frameworks derived from ZIF-8 possess efficiently expanded pores while retaining the original morphology and high nitrogen contents. Compared to those of the normal ZIF-8-derived carbon, the obtained materials exhibit a hierarchically porous structure with a higher specific surface area and an improved pore volume. Electrochemical studies of the obtained electrode demonstrate that this material has a high specific capacitance and lower inner resistance. More importantly, the obtained material shows a higher salt adsorption capacity (20.05 mg/g) than the normal ZIF-8-derived carbon (13.01 mg/g). Furthermore, the obtained electrode presents a rapid salt removal rate and excellent cycling stability. The significantly enhanced deionization behavior of the obtained materials is due to the combination effect of its large accessible surface area, large pore volume, and rich nitrogen doping. The results reveal that in situexpanding pores of carbon frameworks derived from MOFs is an ideal way for constructing electrode materials with enhanced CDI performance. The present work may pave a path for the design and development of highly efficient MOF-derived electrode materials.

Size effects have been recognized to promote the catalytic activity and selectivity of metal oxide particles. So far, limited works and studies are conducted to investigate the size effect of metal oxide with the tailored shape in the selective catalytic reduction of NOxwith NH3(NH3–SCR). Herein, the MnOx-FeOynanocage catalysts with varied scales (0.25, 0.5, 1, and 2 μm) were synthesized via a Prussian blue analogue (PBA)-derived method and used for NH3–SCR of NO. By preforming a series of the activity tests over the nanocages with different scales, the NH3–SCR activity of 0.5 μm MnOx-FeOynanocage catalysts exhibits the highest deNOxactivity in the temperature range of 80–200 °C owing to more preferable physical and chemical properties. It has been demonstrated that there is a strong interaction among Mn and Fe cations in the 0.5 μm MnOx-FeOynanocages. Moreover, the H2-TPR and XPS analysis prove 0.5 μm nanocages exhibit excellent redox properties, which contribute to the higher conservation of NOx. Through the DFT studies, it is also demonstrated that the 0.5 μm MnOx-FeOynanocage catalysts could provide more preferable electronic charge, which gives rise to the varied adsorption behavior of the NH3species and NOxspecies compared to the nanocages with other scales. The in situ DRIFTs were also employed to evaluate the adsorption status of NH3with NOxspecies over MnOx-FeOynanocage catalysts with varied scales. Finally, the scale-activity relationship of the MnOx-FeOynanocage catalysts and their corresponding activities are also established. The deep insight into the scale-activity relationship of the PBA-derived MnOx-FeOynanocage catalyst paves the way for developing and designing highly efficient Mn-based catalyst at lower temperature.

Ultrathin graphite-like carbon nitride (g–C3N4) nanosheets have attracted considerable attention due to the enhanced intrinsic photoabsorption and photoresponse with respect to bulk g–C3N4. For the first time, a dual-mode of down- and upconversion luminescent g–C3N4nanopaper with high optical transparency and mechanical robustness was successfully fabricated through a simple thermal evaporation process using chitosan as a green cross-linking agent. The dual-mode of down- and upconversion fluorescence emission originated from the amino terminated ultrathin g–C3N4nanosheets functionalized with carboxylic acid modified multicolored rare-earth upconversion nanoparticles (cit–UCNPs) via EDC/NHS coupling chemistry. The homogeneously distributed cit–UCNPs@g–C3N4nanoconjugates with excellent hydrophilicity displayed good film-forming ability and structural integrity; thus, the photoluminescence of each ingredient was substantially maintained. Results indicated that the freestanding chitosan cross-linked cit–UCNPs@g–C3N4luminescent nanopaper possessed high transmittance, excellent mechanical properties, and remarkable dual-mode emission. The smart design of high performance luminescent nanopaper based on ultrathin g–C3N4nanosheets grafted with multicolored UCNPs offers a potential strategy to immobilize other multifunctional luminescent materials for easily recognizable and hardly replicable anticounterfeiting fields.

Iron ion (Fe3+) which is the physiologically most abundant and versatile transition metal in biological systems, has been closely related to many certain cancers, metabolism, and dysfunction of organs, such as the liver, heart, and pancreas. In this Research Article, a novel Nile red derivative (NRD) fluorescent probe was synthesized and, in conjunction with polymer-modified core–shell upconversion nanoparticles (UCNPs), demonstrated in the detection of Fe3+ion with high sensitivity and selectivity. The core–shell UCNPs were surface modified using a synthesized PEGylated amphiphilic polymer (C18PMH-mPEG), and the resulting mPEG modified core–shell UCNPs (mPEG-UCNPs) show good water solubility. The overall Fe3+-responsive upconversion luminescence nanostructure was fabricated by linking the NRD to the mPEG-UCNPs, denoted as mPEG-UCNPs-NRD. In the nanostructure, the core–shell UCNPs, NaYF4:Yb,Er,Tm@NaGdF4, serve as the energy donor while the Fe3+-responsive NRD as the energy acceptor, which leads to efficient luminescence resonance energy transfer (LRET). The mPEG-UCNPs-NRD nanostructure shows high selectivity and sensitivity for detecting Fe3+in water. In addition, benefited from the good biocompatibility, the nanostructure was successfully applied for detecting Fe3+in living cells based on upconversion luminescence (UCL) from the UCNPs. Furthermore, the doped Gd3+ion in the UCNPs endows the mPEG-UCNPs-NRD nanostructure with effective T1signal enhancement, making it a potential magnetic resonance imaging (MRI) contrast agent. This work demonstrates a simple yet powerful strategy to combine metal ion sensing with multimodal bioimaging based on upconversion luminescence for biomedical applications.

The Sn4+-doped TiO2nanocrystals with controlled crystalline phase and morphology had been successfully prepared through easily adjusting the solvent system from the peroxo-metal-complex precursor by solvothermal method. The Sn4+-doped TiO2nanocrystals were characterized by XRD, Raman, TEM, HRTEM, XPS, ICP-AES, BET, and UV−vis. The experimental results indicated that the Sn4+-doped TiO2nanocrystals prepared in the pure water or predominant water system trend to form rodlike rutile, whereas the cubic-shaped anatase Sn4+-doped TiO2nanocrystals can be obtained in the alcohol system. The growth mechanism and microstructure evolution of the Sn4+-doped TiO2nanocrystals prepared in the different solvent systems are discussed. The liquid-phase photocatalytic degradation of phenol was used as a model reaction to test the photocatalytic activity of the synthesized materials. It was found that sample Sn4+-doped TiO2prepared in 1-butanol showed the maximum photoactivity, which attributed to higher band gap, optimal crystalline phase and surface state modifications.