Self-template Approach Research Articles

Self-template synthesis of ZnS/Ni3S2 as advanced electrode material for hybrid supercapacitors

In this work, ZnS/Ni3S2 electrode material was synthesized by a simple self-template approach. The synthetic route includes chemical precipitation of Zn–Ni precursor in a polyvinylpyrrolidone (PVP)/Milli-Q water solution by dropping ammonia solution and subsequent conversion of the Zn–Ni precursor to ZnS/Ni3S2via chemical reaction with thioacetamide (TAA), as the sulfur source. Here, the Zn–Ni precursor can be considered as a template that is converted to ZnS/Ni3S2 during the sulfidation process. The synthesized ZnS/Ni3S2 material displays a porous texture and a high specific surface area. These properties are beneficial for the investigation of the developed material as electrode in supercapacitors. Indeed, the obtained ZnS/Ni3S2 material exhibits improved specific capacity of 890.1 C g−1 at 1 A g−1 along with a good rate capability (70% retention of its initial value from 1 A g−1 to 20 A g−1). Furthermore, the ZnS/Ni3S2 electrode achieves a good cycling stability (∼82% retention of its capacity at 10 A g−1 after 6000 charging-discharging cycles). Moreover, ZnS/Ni3S2 is used as a positive electrode and porous reduced graphene oxide (PrGO) as a negative electrode to assemble a hybrid supercapacitor. The fabricated hybrid supercapacitor offers a specific capacity of ∼112.5 C g−1 at 0.5 A g−1, and delivers an energy density of 30.6 W h kg−1 at a power density of 880 W kg−1. This work not only demonstrates that ZnS/Ni3S2 material can serve as an efficient electrode material for supercapacitors, but also provides an easy operation way for preparing high performance metal-sulfide electrodes for energy storage application.

Facile tailoring of Co-based spinel hierarchical hollow microspheres for highly efficient catalytic conversion of CO2

High-performance and low-cost photocatalysts are of significance to artificial photosynthetic systems for converting of CO2 into CO and other value-added products. In this work, we developed a controllable and scalable self-templated approach to fabricate hierarchical Co-base spinel hollow microspheres for visible light-driven CO2 reduction with a Ru-based sensitizer. The hollow microspheres are assembled by ultrathin nanosheets using Ni-Co-hydroxides as the morphology-conserved precursor. A series of characterization techniques were conducted to investigate structural features of the prepared Co-base spinel hollow spheres. Owing to the integration of the specific microstructure, functional Ni/Co species and oxygen vacancies, Co-base spinel hollow spheres possess enhanced CO2 adsorption ability, more active sites, and efficient transfer and separation of photoexcited electrons. The high CO-evolving rate (27.7 μmol h−1) and selectivity (84.4%) manifest desirable performance of Co-base spinel hollow spheres for CO2 photocatalytic reduction. The findings suggest that such spinel-structured bimetallic oxides hierarchical hollow spheres, facilely synthesized via the proposed self-templated method, are efficient for photocatalytic CO2 reduction.

Nanopore-Templated Silver Nanoparticle Arrays Photopolymerized in Zero-Mode Waveguides.

In situ fabrication of nanostructures within a solid-polymer electrolyte confined to subwavelength-diameter nanoapertures is a promising approach for producing nanomaterials for nanophotonic and chemical sensing applications. The solid-polymer electrolyte can be patterned by lithographic photopolymerization of poly(ethylene glycol) diacrylate (PEGDA)-based silver cation (Ag+)-containing polyelectrolyte. Here, we present a new method for fabricating nanopore-templated Ag nanoparticle (AgNP) arrays by in situ photopolymerization using a zero-mode waveguide (ZMW) array to simultaneously template embedded AgNPs and control the spatial distribution of the optical field used for photopolymerization. The approach starts with an array of nanopores fabricated by sequential layer-by-layer deposition and focused ion beam milling. These structures have an optically transparent bottom, allowing access of the optical radiation to the attoliter-volume ZMW region to photopolymerize a PEGDA monomer solution containing AgNPs and Ag+. The electric field intensity distribution is calculated for various ZMW optical cladding layer thicknesses using finite-element simulations, closely following the light-blocking efficiency of the optical cladding layer. The fidelity of the polyelectrolyte nanopillar pattern was optimized with respect to experimental conditions, including the presence or absence of Ag+ and AgNPs and the concentrations of PEGDA and Ag+. The self-templated approach for photopatterning high-resolution photolabile polyelectrolyte nanostructures directly within a ZMW array could lead to a new class of metamaterials formed by embedding metal nanoparticles within a dielectric in a well-defined spatial array.

Coordination polymer derived general synthesis of multi-shelled hollow metal oxides for lithium-ion batteries.

Multi-shelled hollow metal oxide nanostructures have attracted tremendous attention in energy storage devices owing to their high specific capacity, rate capability and ameliorated cycling performance. Although great progress has been made in synthesizing multi-shelled hollow structures, most methods still depend on tedious template mediated strategies to generate complex interior structures. Herein, we developed a facile universal self-templated approach to synthesize a series of multi-shelled hollow metal oxide spheres with tailored compositions. This strategy involved the solvothermal preparation of uniform spherical coordination polymers (CPs) as precursors and a subsequent thermal treatment in air. Single-, binary- and ternary-metal multi-shelled hollow oxide spheres (Co, Mn-Co, Ni-Co, Ni-Co-Mn, etc.) were successfully obtained. To demonstrate their applications in energy storage, the electrochemical properties of ZnCo2O4 were investigated by testing the lithium-ion-storage performance. Owing to the unique structures, the multi-shelled hollow ZnCo2O4 spheres exhibited high specific capacity, excellent cycling durability (1200 mA h·g-1 after 200 cycles at 0.1 A g-1) and prominent rate capability (730 mA h·g-1 at 5.0 A g-1).

MOFs-derived ZnCo–Fe core–shell nanocages with remarkable oxygen evolution reaction performance

MOFs derived ZnCo–Fe nanocages are synthesized by a self-templated approach showing the remarkable performance for OER catalysts.

Synthesis of a palladium acetylide-based tubular microporous polymer monolith via a self-template approach: a potential precursor of supported palladium nanoparticles for heterogeneous catalysis

A monolithic, palladium acetylide-based conjugated microporous polymer, Pd-CMP, was synthesized from a palladium dichloride and a trialkyne. The polymerization proceeded in two different ways, the dehydrohalogenation reaction between the alkyne and the palladium halide and the homocoupling reaction of the alkyne. Pd-CMP had a rigid hollow tubular structure. The in situ formed crystalline triethylammonium chloride (TEACl) rod played a critical role in the formation of the tubular morphology as a template. Through the attachment of the polymer particles to the surface of the rod and their reactions with soluble alkynes, a core–shell structure with a TEACl core and a polymer shell formed. The TEACl core was removed by washing with methanol to yield a hollow polymer tube. Pd-CMP showed a hierarchical pore structure and reversible compressibility. Supported Pd nanoparticles were prepared by one-step thermolysis of Pd-CMP as a heterogeneous catalyst. The average diameters of NPs in the products thermolyzed at 300 (Pd-CMP300) and 500 °C (Pd-CMP500) were 2.6 and 4.1 nm, respectively. Pd-CMP300 was used in the heterogeneous catalysis of the 4-nitrophenol reduction reaction and Suzuki–Miyaura coupling between iodobenzene and phenylboronic acid. The reaction yields were higher than 95%. The catalyst could be used for a flow reaction and easily recycled without significant activity loss.

Self-Templated Formation of Interlaced Carbon Nanotubes Threaded Hollow Co3S4 Nanoboxes for High-Rate and Heat-Resistant Lithium-Sulfur Batteries.

Lithium-sulfur batteries (Li-S) have attracted soaring attention due to the particularly high energy density for advanced energy storage system. However, the practical application of Li-S batteries still faces multiple challenges, including the shuttle effect of intermediate polysulfides, the low conductivity of sulfur and the large volume variation of sulfur cathode. To overcome these issues, here we reported a self-templated approach to prepare interconnected carbon nanotubes inserted/wired hollow Co3S4 nanoboxes (CNTs/Co3S4-NBs) as an efficient sulfur host material. Originating from the combination of three-dimensional CNT conductive network and polar Co3S4-NBs, the obtained hybrid nanocomposite of CNTs/Co3S4-NBs can offer ultrahigh charge transfer properties, and efficiently restrain polysulfides in hollow Co3S4-NBs via the synergistic effect of structural confinement and chemical bonding. Benefiting from the above advantages, the S@CNTs/Co3S4-NBs cathode shows a significantly improved electrochemical performance in terms of high reversible capacity, good rate performance, and long-term cyclability. More remarkably, even at an elevated temperature (50 °C), it still exhibits high capacity retention and good rate capacity.

Metal-organic framework-derived porous shuttle-like vanadium oxides for sodium-ion battery application

Vanadium oxides with a layered structure are promising candidates for both lithium-ion batteries and sodium-ion batteries (SIBs). The self-template approach, which involves a transformation from metal-organic frameworks (MOFs) into porous metal oxides, is a novel and effective way to achieve desirable electrochemical performance. In this study, porous shuttle-like vanadium oxides (i.e., V2O5, V2O3/C) were successfully prepared by using MIL-88B (V) as precursors with a specific calcination process. As a proof-of-concept application, the asprepared porous shuttle-like V2O3/C was used as an anode material for SIBs. The porous shuttle-like V2O3/C, which had an inherent layered structure with metallic behavior, exhibited excellent electrochemical properties. Remarkable rate capacities of 417, 247, 202, 176, 164, and 149 mAh·g−1 were achieved at current densities of 50, 100, 200, 500, 1,000, and 2,000 mA·g−1, respectively. Under cycling at 2 A·g−1, the specific discharge capacity reached 181 mAh·g−1, with a low capacity fading rate of 0.032% per cycle after 1,000 cycles. Density functional theory calculation results indicated that Na ions preferred to occupy the interlamination rather than the inside of each layer in the V2O3. Interestingly, the special layered structure with a skeleton of dumbbell-like V–V bonds and metallic behavior was maintained after the insertion of Na ions, which was beneficial for the cycle performance. We consider that the MOF precursor of MIL-88B (V) can be used to synthesize other porous V-based materials for various applications.

Self-assembly-template engineering nitrogen-doped carbon aerogels for high-rate supercapacitors

Three-dimensional (3D) interconnected porous nitrogen-doped carbon aerogels (CAs) have been successfully prepared with polyvinyl alcohol and nitrogen-containing N-phenylethanolamine as carbon and in-situ nitrogen sources, and boric acid as both crosslinking agent and 3D self-template. After drying, carbonization and KOH-activation treatment, the as-obtained CAs exhibit large specific surface area, hierarchically porous structure, heteroatom doping and superhydrophilicity. The optimal sample shows a high surface area up to 2016m2g−1 with a total pore volume of 1.179cm3g−1. The synergistic effect of the reasonably hierarchical porosity, high effective surface area utilization, superhydrophilicity, and heteroatom pseudocapacitance are in favor of high specific capacitance of 467Fg−1 in three-electrode system and considerable cycle performance of 85.7%, 90.9% retention over 10,000 cycles at 20Ag−1 and 30Ag−1. Moreover, the symmetric supercapacitor configuration delivers an energy density of 22.75Whkg−1 at power density of 262.5Wkg−1 and 7.6Whkg−1 at power density of 9572Wkg−1. Here, we pioneer an in-situ self-template approach for fabricating hierarchically porous aerogels with a potential application in supplying a peak power for hybrid electric vehicles, memory backup systems, cold-starting assistants and especially electrochromic devices as demonstrated in our case.

Eliminating rib shadows in chest radiographic images providing diagnostic assistance

A major difficulty with chest radiographic analysis is the invisibility of abnormalities caused by the superimposition of normal anatomical structures, such as ribs, over the main tissue to be examined. Suppressing the ribs with no information loss about the original tissue would therefore be helpful during manual identification or computer-aided detection of nodules on a chest radiographic image. In this study, we introduce a two-step algorithm for eliminating rib shadows in chest radiographic images. The algorithm first delineates the ribs using a novel hybrid self-template approach and then suppresses these delineated ribs using an unsupervised regression model that takes into account the change in proximal thickness (depth) of bone in the vertical axis. The performance of the system is evaluated using a benchmark set of real chest radiographic images. The experimental results determine that proposed method for rib delineation can provide higher accuracy than existing methods. The knowledge of rib delineation can remarkably improve the nodule detection performance of a current computer-aided diagnosis (CAD) system. It is also shown that the rib suppression algorithm can increase the nodule visibility by eliminating rib shadows while mostly preserving the nodule intensity.

Synthesis of Mesoporous Nickel-Silica Hollow Microspheres Catalysts and Its Catalytic Performance

The mesoporous nickel spheres catalysts with tunable chamber structures have been successfully prepared by liquid phase reduction of Ni3Si2O5(OH)4 microspheres at 120°C, which are synthesized by the reaction between Ni(Ac)2·4H2O and SiO2 microspheres via a self-template approach. This material with large BET surface area (158 m2/g) exhibits good catalytic activity and high selectivity in nitrobenzene hydrogenation reaction. The selectivity rate of the phenylamine reached to 99.85% and the conversion rate of the nitrobenzene was almost up to 100%, showing the potential application in the catalyst industry.

Controlled synthesis and catalytic properties of mesoporous nickel–silica core–shell microspheres with tunable chamber structures

In 550°C and H2 current, the mesoporous nickel–silica composite core–shell microspheres with tunable chamber structures have been successfully prepared by reduction of Ni3Si2O5(OH)4 microspheres, which are synthesized by the reaction between Ni(Ac)2·4H2O and SiO2 microspheres via a self-template approach. The chamber (SiO2 core sizes) and shell thickness (40–150nm) of the nickel–silica microspheres can be controlled by adjusting the synthetic parameters of Ni3Si2O5(OH)4, such as the reaction time. After reduction, these microspheres still have the same sizes, morphologies, and core–shell structures with porous shell as before. These mesoporous nickel–silica microspheres with large BET surface area, exhibit good catalytic activity in m-dinitrobenzene (m-DNB) and high selectivity of m-phenylenediamine (m-PDA) after 3.5h, but different selectivity of m-PDA in the progress, showing good potential in the catalyst industry.

A facile strategy for in situ core-template-functionalizing siliceous hollow nanospheres for guest species entrapment.

The shell wall-functionalized siliceous hollow nanospheres (SHNs) with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin) provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+), without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-)molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating) molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures.

A Self-Templated Route to Hollow Silica Microspheres

A simple, mild, and effective self-templated approach has been developed to directly convert solid SiO2 microspheres into hollow structures. The reaction involves initial partial dissolution of silica cores in a NaBH4 solution and subsequent shell formation due to the redeposition of the silicate species back onto the colloid surfaces. The increasing concentration of NaBO2 as the result of the slow decomposition of NaBH4 in water is found to be responsible for the regrowth of the silica shell. This method allows the production of hollow silica spheres with sizes ranging from ∼70 nanometers to several micrometers, largely determined by the size of the starting silica colloids. The solid-to-hollow transformation mechanism is investigated in detail by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectrometry, X-ray absorption spectroscopy (XAS), N2 adsorption−desorption, and X-ray diffraction (XRD). We also study the reaction conditions that allow control over the wall thickness, surface morphology, and shell porosity.

Controlled synthesis of mesoporous SiO2/Ni3Si2O5(OH)4 core–shell microspheres with tunable chamber structures via a self-template method

Mesoporous SiO2/Ni3Si2O5(OH)4 core-shell microspheres with tunable chamber structures have been synthesized by the reaction between Ni(Ac)2.4H2O and SiO2 microspheres via a simple self-template approach.

A Self-Templated Approach to TiO2 Microcapsules

A self-templated approach has been developed for the synthesis of TiO2 microcapsules with tunable size and wall thickness by heating sol-gel derived TiO2 microspheres with poly(acrylic acid) (PAA) in a diethylene glycol (DEG) solution. PAA plays a crucial role in the formation of microcapsules by crosslinking the surface TiO2 nanoparticles and preventing them from dissolution by DEG. Hollow microcapsules form when DEG molecules penetrate the outer layer and remove the core materials by forming soluble titanium glycolate.