Template-free Synthesis Research Articles

Precise morphology control of phosphate-based nanospheres via magnesium and application in drug delivery

The present work investigates a template-free and rapid synthesis of phosphate-based porous nanospheres via magnesium. The study reveals the magnesium plays a guide role in the formation of amorphous porous magnesium substituted nanospheres, including calcium phosphate (CaP), strontium phosphate (SrP) and barium phosphate (BaP). Cell viabilities of three kinds of particles were evaluated and CaP nanospheres indicated best biocompatibility. Thus, amorphous magnesium substituted CaP nanospheres were chosen as doxorubicin (DOX) carrier for drug delivery in cancer treatment and pH-responsive magnesium substitution can switch on under tumour acidic microenvironment and facilitate controlled sustained DOX release. The CaP nanospheres gave a sustainable release within 150 minutes. The results showed free DOX has better efficiency at killing cancer cells than CaP/DOX at 4 h. However, CaP/DOX systems effectively suppressed the cell proliferation comparing with free DOX at 36 h. Collectively, this simple and templet-free method for synthesis of amorphous porous nanospheres could serve as a promising chemo-therapeutics delivery system and effectively inhibition of cancer cell growth.

Template-free synthesis of β-NiS ball-in-ball microspheres for a high-performance asymmetrical supercapacitor.

While significant advances have been made in the synthesis of core-/multi-shell materials, the synthetic process usually involves a soft/hard template and complicated procedures. In particular, it is extremely difficult to fabricate single-component core-shell structures for nickel sulfides (NSs) with a controlled phase. In this work, we demonstrate a novel facile method to synthesize a single-component β-NiS ball-in-ball microsphere. The ball-in-ball structure is easily obtained by uniquely employing 2-mercaptopropionic acid (2-MPA) as the sulfur source and ethanol as the solvent based on the Ostwald ripening process. In particular, our work demonstrates that the chemical structure of sulfur sources and solvents plays a key role in the formation of the pure β-NiS ball-in-ball structure. When used as an electrode active material, the β-NiS ball-in-ball microspheres exhibit two times stronger specific capacity and three times higher rate performance than NSs produced by a hydrothermal method. The fabricated NS-2//rGO asymmetrical supercapacitor (ASC) displays an energy density of 46.4 W h kg-1 at a power density of 799.0 W kg-1 and good cycling performance. Thus, this study provides a new method for controlling the phase and morphology of NSs.

Fe induction strategy for hollow porous N-doped carbon with superior performance in oxygen reduction.

An Fe induction strategy is introduced to achieve template-free synthesis of Co,Fe dual-metal N-codoped hollow porous carbon from zeolitic imidazole frameworks, which is beneficial for the exposure of highly dispersed metal (M)-Nx active sites and enhancement of mass transport, thereby exhibiting a superior electrocatalytic activity (E1/2, 0.86 VRHE).

New insight into the inductive effect of various seeds on the template-free synthesis of ZSM-5 zeolite

This work enables us to obtain an improved understanding of the role of seeds in the template-free synthesis of zeolite.

Template-free synthesis of polyacrylonitrile-derived porous carbon nanoballs on graphene for efficient oxygen reduction in zinc–air batteries

Introducing abundant active sites and improving their activity are two critical considerations for designing metal-free nitrogenous electrocatalysts for the oxygen reduction reaction (ORR) in energy conversion devices such as metal–air batteries and fuel cells.

Template-free synthesis of hierarchical nanocrystal UiO-66 and its adsorption thermodynamics for n-heptane and methyl cyclohexane

NH4OH can induce rapid crystallization of the precursors, whereas acetic acid can effectively stabilize such precursors and control the balance between nucleation and growth of UiO-66.

Template-free synthesis of non-noble metal single-atom electrocatalyst with N-doped holey carbon matrix for highly efficient oxygen reduction reaction in zinc-air batteries

M-N-C single-atom electrocatalysts recently have received significant attention because of high catalytic activity and maximal atom utilization. Here, it is firstly reported that macrocycle cucurbit[6]uril (CB[6]) self-assembly was employed as precursor to fabricate M-N-C single-atom electrocatalysts for the Zn-air battery (ZAB). This template-free method using CB[6] self-assembly acquires the holey N-doped matrixes with hierarchical micro/mesoporous structure. The Fe loaded N-doped holey carbon single-atom electrocatalyst (Fe-NHC) exhibited high activity with the half-wave potential (E1/2) of 0.89 V versus reversible hydrogen electrode (RHE) for oxygen reduction reaction (ORR) in alkaline condition, which was better than those of Co or Ni loaded catalyst and commercial Pt/C (E1/2 = 0.83 V). Moreover, the ZAB employing Fe-NHC catalyst achieved higher power and energy density with longer-term stability than those of Pt/C + Ir/C catalyst. This work provided a promising strategy to design stable and highly efficient catalyst for long-life electrochemical storage devices.

Template-free synthesis of Vanadium Nitride Nanopetals (VNNP) as a high performance counter electrode for dye sensitized solar cells

The thrust of finding an alternative and noble metal free counter electrode (CE) for dye sensitized solar cells (DSSCs) encouraged the present study on new and unique structure of vanadium nitride nanopetals as counter electrode for DSSCs. Template-free vanadium nitride nanopetals were successfully synthesized by high temperature ammonia treatment of the precursor material viz. V2O5/melamine. The material analysis reveals the formation of highly crystalline vanadium nitride with mesoporous crosslinked intertwined nanopetals with pronounced electrocatalytic active sites leading to an excellent catalytic performance towards iodide/triiodide electrolyte, fast charge transfer kinetics, electron diffusion and low charge transfer resistance. The fabricated dye sensitized solar cell sandwiched with N719 dye loaded photoanode and VN nanopetals CE with an injection of iodide/triiodide electrolyte showed a significant power conversion efficiency (PCE) of 7.44%, which is higher than Pt CE (7.38%) under the same testing conditions. Results thus proved that the material is a promising candidate as an alternative counter electrode for Pt in DSSC.

Template-free synthesis of high specific surface area gauze-like porous graphitic carbon nitride for efficient photocatalytic degradation of tetracycline hydrochloride

Toxic solvents and chemicals are usually used to prepare carbon nitride. Therefore, a low-toxic template-free method was proposed to prepare gauze-like porous graphitic carbon nitride (CCM18) with high specific surface area. The morphology, crystal and surface structure, specific surface area and optical properties of CCM18 were characterized, and the removal efficiency for tetracycline hydrochloride (TC) degradation under simulated sunlight was evaluated. The results showed that CCM18 has a specific surface area of 107.4 m2 g-1, stronger light absorption capacity and a band gap energy of 2.92 eV. The degradation rate of TC by CCM18 was more than twice that of BCN. The experiment of radical scavengers confirmed that superoxide radicals (O2-) and hydroxyl radical (OH) were the major active species. The enhanced performance of CCM18 for TC degradation (82%) and the stability of CCM18 that can be reused multiple times indicated the prospect of industrial application.

Detection of hydrogen peroxide involving bismuth nanowires via template-free electrochemical synthesis using deep eutectic solvents

Nanomaterials with different morphologies have been important in the development of electrochemical sensors with applications in the biomedical field. In the last decade, there has been increasing interest in Bi-based nanostructures for sensing applications where green strategies are preferred. The template-free synthesis of Bi nanowires (BiNWs) involving deep eutectic solvents (DESs) as electrolytes has enabled the fabrication of a sensing platform with electrocatalytic activity towards hydrogen peroxide. The target molecule plays an important part in the development of cancers and its detection could shed light on the dynamics related to cellular metabolism, with applications in medical research. The BiNW-based platform is shown to detect the molecule of interest in the presence of common interfering agents and offers avenues for further development.

Seed-assisted template-free synthesis of nano-sized ZSM-5 via two-stage crystallization with related investigation of mechanism

High crystalline and well dispersed nano-ZSM-5 was rapidly synthesized in template-free system using high-low temperature two-stage process with as-synthesized silicalite-1 as the seed, and characterized via XRD, SEM, N2 adsorption, FT-IR, Py-IR, TG and so on. Firstly, seed-assisted one-stage crystallization was examined and the results showed that high crystalline nano-ZSM-5 (>90%) could be obtained at 180 °C and 220 °C when the duration time was more than 12 h and 2 h, respectively, but the products tended to be agglomerated with the increase of crystallinity. Based on this, two-stage crystallization was comparatively studied between 220 °C/1 h-180 °C/1–6 h and 220 °C/4 h-180 °C/1–4 h, and high crystalline ZSM-5 (Z-1-6) (97%) with the size of 70–90 nm and good dispersion was synthesized at 220 °C/1 h-180 °C/6 h, while submicron aggregates consisted of 60–120 nm irregular cuboids with high crystallinity (>90%) were obtained at 220 °C/4 h-180 °C/1–4 h. Structural and acidic characterization indicated that Z-1-6 had excellent surface adsorption properties and moderate acidity compared with the commercial micron-ZSM-5. Finally, seed-assisted two-stage crystallization mechanism was proposed about accelerating the depolymerization of silicalite-1 into more smaller nucleation sites and avoiding the aggregation of crystal nuclei by controlling a shorter duration time at a higher temperature and ensuring the stable growth of nano-crystals at a lower temperature.

Pitch-Based Laminated Carbon Formed by Pressure Driving at Low Temperature as High-Capacity Anodes for Lithium Energy Storage Systems.

Pitch has been used to prepare electrodes by high-temperature heat treatments for supercapacitors, lithium-ion batteries, on account of its rich aromatic ring structure. Here, the toluene-soluble component of pitch is used to prepare a kind of laminated carbon. This was realized by a template-free synthesis at low temperature with the addition of pressure. The toluene-soluble component has a small molecular weight, which makes the thermal deformation ability stronger and then enhances the orientation of the carbon layer with the help of pressure. The prepared anode exhibits a splendid electrochemical performance compared with the traditional graphite anode. A high stable capacity of approximately 550 mAh g-1 at 50 mA g-1 , which is much higher than graphite (372 mAh g-1 ), is obtained. Also, when the current density is up to 2 A g-1 , the capacity is about 150 mAh g-1 . Surprisingly, it also delivers a superior cycling performance. And when used as the anode/cathode electrode for lithium-ion capacitors, a high energy density can be obtained. The present work offers an opportunity to utilize the pitch source in lithium energy storage with promising cycle life, high energy/power density, and low cost.

Formation process and pervaporation of high aluminum ZSM-5 zeolite membrane with fluoride-containing and organic template-free gel

The formation progress of the high aluminum ZSM-5 zeolite membrane was investigated and characterized with the organic template-free and fluoride-containing initial synthesis gel. The nano spherical Silicalite-1 seed crystals were dissolved into amorphous by the fluoride-containing precursor synthesis gel. The amorphous contained elementary structural units (TO4) and isolated five-membered ring structure of MFI zeolites. These were retained to provide the nucleation sites for high aluminum ZSM-5 zeolite. The ZSM-5 zeolite nucleus was grown into fine needle-like ZSM-5 zeolites, which were gradually grown into twin crystals, aggregation and compact ZSM-5 zeolites layer on the support without the organic template initial synthesis gel. In addition, the high aluminum ZSM-5 zeolite membranes kept the identical morphology and structure for separation of high concentration acetic acid (H2O/HAc) or inorganic acid (1 M H2SO4) aqueous mixtures by XRD, SEM and NMR characterization. Furthermore, the membrane had a good dehydration performance and acid-stability by pervaporation. The flux and separation factor of the membrane for 10 wt% H2O/HAc mixtures were 0.98 kg∙m−2∙h−1 and 3200 at 348 K, respectively.

Solid-State and Organic Template-Free Synthesis of Zeolite Omega by Conversion of Magadiite in the Presence of Seed Crystals and Investigation of Conversion Mechanism

In this work, we developed a sustainable synthesis of zeolite omega via the conversion of magadiite under solid-state and organic template-free conditions. The conversion behavior and mechanism wer...

Template-free synthesis of hierarchical mesoporous carbon: Based on functional coal tar pitches with carboxylation and diketone structures

An efficient and easy template-free method for the preparation of hierarchical porous carbons (HPCs) has been developed using low-priced coal tar pitch (CP) as the starting material. Application of the diketone (-COCO-) radical provides a carbonyl methylene group for polycyclic aromatic hydrocarbons by condensation and produces an effective micro-mesoporous network with a high specific surface area. With the help of controlled Friedel-Crafts reaction and oxidation, carboxyl-functionalized CP is obtained as the stratified porous CP precursor, and the high-temperature decarboxylation (>230°C) helped in generating well-developed micro-mesoporous carbon. The total pore volume of porous carbon of 1277.3 and 1.45 cm 3 g -1 the maximum BET surface area suggests that the rapid electrolyte ion exchange and charge transportability would be better for the electrochemical capacitor.

Environmentally benign synthesis of crystalline nanosized molecular sieves

Zeolites and zeo-type materials with nanosized dimensions are of great practical interest owing to their favorable transport properties, faster adsorption kinetics, and large external surface area. This mini-review presents recent developments in the organic template-free synthesis of nanosized zeolites and related materials. The advantages and challenges of these methods are addressed with particular attention to the green synthesis of nanozeolites.

Template-free synthesis to micro-meso-macroporous hierarchy in nanostructured MIL-101(Cr) with enhanced catalytic activity

MIL-101(Cr)是最重要的金属有机框架(MOFs)材料之一, 稳定的框架结构和超高的比表面积使其在众多科学领域得到了广泛研究和应用. 但是MIL-101(Cr)的合成条件比较苛刻, 且稳定性较强, 因此, 有关于其分级结构的研究报道仍比较少. 本文提出了一种简单制备分级纳米孔结构MIL-101(Cr)的方法, 即以乙酸作为调节剂, 采用水热合成的方法, 一步得到具有微孔-介孔-大孔分级结构的MIL-101(Cr)材料. 实验结果表明, 该分级结构的MIL-101(Cr)与无分级结构的MIL-101(Cr)相比, 其大分子染料吸附能力和催化能力均有显著提高. 而且分级结构MIL-101(Cr)负载了磷钨酸催化剂之后, 表现出了与均相催化剂(纯磷钨酸)相当的催化能力. 进一步研究发现, 使用其他短碳链的一元羧酸作为调节剂, 如丙酸、丁酸等, 也可获得类似分级纳米结构MIL-101(Cr).

Template-free synthesis of novel Co3O4 micro-bundles assembled with flakes for high-performance hybrid supercapacitors

In this paper, a novel Co3O4 micro-bundles structure (Co3O4 MBs) was obtained at 120 °C after a hydrothermal reaction for 24 h and followed by an annealing treatment at 300 °C in air. The unique Co3O4 MBs are constructed by many adjacent flakes with 0.4 μm in thickness, and exhibit a large surface area of 81.2 m2 g−1 and a mean pore diameter of 6.14 nm, which may facilitate a sufficient contact with electrolyte and then shorten the diffusion pathway of ions. A remarkable electrochemical behavior including specific capacity of 282.3 C g−1 at 1 A g−1 and 205.9 C g−1 at 10 A g−1, and an excellent cycling performance with 74.6% capacity retention after 4000 charge-discharge process at 5 A g−1 are achieved when the test of Co3O4 MBs-modified electrode is performed using three-electrode configuration. Additionally, a hybrid supercapacitor (HSC) was fabricated with the obtained Co3O4 MBs as positive electrode and commercial activated carbon (AC) as negative electrode. The HSC exhibits a specific capacity of 144.1 C g−1 at 1 A g−1 and 126.4% capacity retention after 5000 cycles at 5 A g−1. An energy density of 38.5 W h kg−1 can be obtained at a power density of 962.0 W kg−1, and 29.5 W h kg−1 is still retained at 8532.5 W kg−1. The simple synthetic strategy can be applicable to the synthesis of other transition metal oxides with superior electrochemical performance.

Template-free synthesis and photocatalytic activity of hierarchical hollow ZnO microspheres composed of radially aligned nanorods

In this work, hierarchical hollow ZnO microspheres with an average diameter of 3.5 μm are successfully synthesized via a simple template-free solvothermal route. And these microspheres are constructed by anisotropic single-crystalline ZnO nanorods which grows along the [0001] c-axis direction because of the selective adsorption of ethylene glycol. It is noted that ethylene glycol plays a crucial role in promoting the growth and aggregation of nanorod by comparing the effect of other solvents, such as water, ethanol, isopropanol and glycerol. Furthermore, the photocatalytic activity of as-obtained hollow ZnO microspheres is evaluated by the degradation of methylene blue (MB) in aqueous solution. The photocatalytic performance reveals that these hollow ZnO microspheres can not only efficiently degradate the dye, but also show good stability during the cycling photodegradation.

Template-free synthesis of mesh-like graphic carbon nitride with optimized electronic band structure for enhanced photocatalytic hydrogen evolution

It is greatly significant to develop a facile strategy to optimize the nanostructure and chemical structure of graphic carbon nitride (GCN) for improved photocatalytic activity. In this work, a novel mesh-like GCN (MGCN) with tunable porous structure and condensation degree was successfully developed via a template-free strategy using supramolecular aggregate melamine cyanuric acid complex (MCA) as precursor. The as-obtained MGCN is endowed with more exposed active sites, narrower bandgap, higher electric conductivity, and greatly accelerate mass and photogenerated charge transfer, which are favorable for improving the efficiency of visible-light absorption, photogenerated carriers separation and interfacial redox reaction. Therefore, all the MGCN samples exhibit a superior performance in photocatalytic hydrogen evolution activity under visible-light irradiation. Furthermore, the hydrogen evolution rate (HER) of MGCN are enhanced with the increasing of calcination temperature. The optimum materials (MGCN-600) shows an excellent hydrogen evolution rate (~137.3 μmol h−1), which is up to 25 times higher than that of bulk GCN (BGCN), and with a remarkable apparent quantum efficiency (AQE) of 13.5% at 400 nm. This work provides a scale-up strategy in the design and synthesis of photocatalysts with controlled nanostructure and chemical structure for broad applications in photocatalysis.