Hard Template Method Research Articles

Designing MnO2@amorphous carbon core-shell structure as a cathode to enhance rate performance and cycling stability of aqueous zinc-ion batteries

Manganese dioxide has received significant attention as a prospective cathode material in aqueous zinc-ion batteries (ZIBs) owing to its elevated working voltage and commendable energy density. Nevertheless, challenges such as structural instability, manganese dissolution, and poor electrical conductivity remain significant barriers to the practical application of research. Here, the MnO2 nanorods encapsulated in the amorphous carbon (MnO2@C) with core-shell structure are prepared by a special hard template method, and investigated as cathode materials for ZIBs. The amorphous carbon, characterized by its structural defects and disorder, manifests heightened active site density, thereby establishing an efficient conduit for charge transport. Concurrently, the nano-dimensional interstitial spaces augment the active sites available for zinc insertion reactions, thereby effectively curtailing the ion diffusion path and, consequently, engendering heightened electrochemical performance. Moreover, the distinctive core-shell architecture of MnO2@C not only furnishes substantial spatial accommodation but also serves to alleviate volume alterations throughout charge and discharge events. Consequently, MnO2@C demonstrates outstanding electrochemical performance, with reversible capacities of 210 mAh·g−1 and 50 mAh·g−1 at 0.1 A·g−1 and 1.6 A·g−1, respectively. Furthermore, even after 600 cycles at 0.8 A·g−1, it maintains exceptional cycling performance, reaching 102 mAh·g−1, endowing MnO2@C cathodes with robust competitiveness in aqueous ZIBs.

Catalytic potential of green ordered mesoporous carbons, obtained from biomass-derived xylose, glucose, and lignin

Green high-surface area Ordered Mesoporous Carbons (OMCs) (576–948 m2/g) were successfully synthesized by the hard template method using xylose, glucose and lignin solutions obtained from almond shells, a local biomass waste, as carbon precursors, and SBA-15 as a template. The catalytic potential of OMCs, as catalytic supports or as catalysts, has been preliminarily tested for different reactions of interest. A dried sulfonic-acid treated OMC, obtained from xylose extract, led to full conversion and 92% selectivity to di- and tri-ethers of glycerol for the glycerol etherification with isobutene at 80 °C. A sulfonic-acid treated OMC, obtained from glucose, presented a higher turnover frequency (TOF) value and slightly lower selectivity to levulinic acid than commercial Amberlyst-15 for the conversion of 5-hydroxymethylfurfural at 180 °C. The use of an OMC obtained from lignin as catalytic support of a nickel catalyst combined with H-Beta led to 78% of selectivity to cyclohexane at total conversion for the hydrodeoxygenation of guaiacol at 180 °C.

Metal-Free Nitrogen-Doped Mesoporous Carbons for the Mild and Selective Synthesis of Pyrroles from Nitroarenes via Cascade Reaction.

The cascade synthesis of pyrroles from nitroarenes is an attractive alternative strategy. However, metal catalysts and relatively high temperatures cover the existing reported catalytic systems for this strategy. The development of nonmetallic heterogeneous catalytic systems for the one-pot synthesis of pyrrole from nitroarenes under mild conditions is both worthwhile and challenging. Herein, we describe an exceptionally efficient method for the synthesis of N-substituted pyrroles by the reductive coupling of nitroarenes and diketones over heterogeneous metal-free catalysts under mild conditions. Nonmetallic NC-X catalysts with high activity were prepared from the pyrolysis of well-defined ligands via simple sacrificing hard template methods. Hydrazine hydrate, formic acid, and molecular hydrogen can all be used as reducing agents in the hydrogenation/Paal-Knorr reaction sequence to efficiently synthesize various N-substituted pyrroles, including drugs and bioactive molecules. The catalytic system was featured with good tolerance to sensitive functional groups and no side reactions such as dehalogenation and aromatics hydrogenation. Hammett correlation studies have shown that the electron-donating substituents are beneficial for the one-pot synthesis of N-substituted pyrroles. The results established that the outstanding performance of the catalyst is mainly attributed to the contribution of graphitic N in the catalyst as well as the promotion effect of the mesoporous structure on the reaction.

Mesoporous silica-based pH/enzyme dual-response system: Nanoparticles for smart delivery of indoxacarb with improved insecticidal activity and biocompatibility

Mesoporous silica nanoparticles (MSN) are ideal carriers for agrochemical control release systems due to their smart environmental stimulus response by easy modification. Herein, MSN loaded with indoxacarb (IN) were successfully prepared using the hard template method. Dopamine (DA) and α-cyclohexapentylose (α-CD) were encapsulated around the MSN surface to obtain pH and enzyme dual-response nanoparticles (IN@MSN@PDA@α-CD). The prepared nanoparticles showed a spherical core-shell structure with a loading content of 22.5 %, and the polymer coating covering the surface of the nanoparticles effectively protected IN from photolysis. Moreover, different biostimuli associated with Spodoptera frugiperda can trigger the release of IN from nanoparticles. Compared with the commercial emulsifiable concentrate (14.93 mg L−1), IN@MSN@PDA@α-CD (8.89 mg L−1) extended the effective duration of IN against Spodoptera frugiperda, and considerably decreased the toxicity of IN to Eisenia fetida, zebrafish and human BEAS-2B cells. Thus, pH/enzyme dual-responsive nanoparticles have substantial potential for sustainable on-demand targeted delivery of agrochemicals and for improving their environmental safety.

Eggshell as a biotemplate for the synthesis of layered porous carbon by co-pyrolysis with eucalyptus leaves

Based on its substantial specific surface area (SSA), quick ion transport path, and excellent pore structure, biomass carbon is a common ingredient in energy storage materials. In this study, hierarchical porous carbon was fabricated by the hard template method, using eucalyptus leaves (EL) as raw material, eggshells (ES) obtained from biomass waste act as a green biotemplating agent, and through co-pyrolysis technology to acquire high-value biomass carbon materials. A large SSA with a hierarchical porous structure displayed a honeycomb appearance obtained by adding eggshells in appropriate proportions. The ELES0.25 electrodes demonstrated a specific capacitance (Cs) of 310 F g−1 (0.5 A g−1) and 232 F g−1 (20 A g−1) in a three-electrode system, which displayed a capacitance retention of 74.8% with an outstanding electrochemical stability. The assembled ELES0.25//ELES0.25 symmetric supercapacitor displays a desirable energy density of 7.35 Wh kg−1 at a power density of 65 W kg−1 and preserves a capacitance retention of 97.38% after a charge/discharge cycle for 10,000 times. This research on ES acts as the biological template for assisted pyrolysis synthesis of porous carbon and proposes a novel approach for the clean and effective use of biomass waste.

A modified hard-templating for hollow mesoporous silica nanoparticles with suitable particle size and shortened synthetic time

Hollow mesoporous silica nanoparticles (HMSN), a member of mesoporous silica family synthesized mainly with har-templating method, has gained great interest in pharmaceutical applications due to their impress characteristics such as good biocompatibility, large specific surface area and pore volume, controllable particle size, large cavity for cargo loading, and flexible surface functionalization possibilities. However, controlling the optimal particle size and shortening the synthesis time have been the issues of HMSN synthesis that needed to be improved. In this study, HMSN was synthesized using hard-templating with some modifications to shorten the synthesis time and adjust the particle size to nearly 100 nm. The obtained HMSN particles showed high uniform morphology as spheres with hollow core-mesoporous shell structure, having the particle diameter of about 90 nm, the hollow diameter of about 68 nm, and the mesoporous shell thickness of about 11 nm. The total time for the main reactions was shortened by more than half from 21 hours to 9 hours. Additionally, MTT assays revealed that the synthesized HMSN was biocompatible material. This modified hard-template method with shorter synthesis time and nearly 100 nm obtained particle diameter would be meaningful for scientific research and industrial scale production.

Remarkably enhanced catalytic performance of three-dimensional hierarchically porous Mo2C catalysts for higher alcohols synthesis from syngas

Higher alcohols synthesis (HAS) is an important branch of syngas conversion, and Mo2C-based catalyst is a promising system for this reaction. However, the CO conversion and alcohols selectivity of current Mo2C-based catalysts are still low, which hinders their industrial application. Here, a series of Mo2C with three-dimensional hierarchically porous (3DHP) structures were prepared via a hard template method and their catalytic performance in HAS was investigated. The CO conversion and higher alcohols proportion of the optimal 3DHP catalyst were increased from 5.1 % and 60.4 % to 17.6 % and 70.5 %, respectively, compared with that of bulk Mo2C under similar total alcohols selectivity. The enhancement of the catalytic performance could be related to the increased number of active sites and the synergistic effect between multivalent Mo species. Additionally, the optimal 3DHP catalyst demonstrated good stability over a period of 200 h. This study provides a potential application for 3DHP materials and an alternative for designing efficient Mo2C catalysts for the HAS reactions.

Preparation of inexpensive S-doped porous carbons for high-performance supercapacitors

Low-cost sulfur-doped porous carbons were prepared through hard template method by using inexpensive colloidal SiO2 nanoparticles as template, glucose as carbon source, H2SO4 as pre‑carbonized reagent and sulfur source. The effects of H2SO4 and carbonization temperature on the microscopic morphology, the pore structure and the specific surface area of porous carbons were explored through multiple characterization methods. The capacitive performance of porous carbons was investigated by multiple electrochemical methods. It was found that the pore structure, specific surface area and the content of sulfur element of carbon are highly dependent on the carbonization temperature. The sulfur-doped porous carbon SPC-900 has much larger surface area and larger pore volume, and thus much better capacitive performance than un-doped PC-900, indicating that H2SO4 can increase the surface area and the pore volume during the preparation process. SPC-900 offers the advantages of lower cost, larger pore size, higher pore volume, better capacitive performance and better rate performance compared to expensive mesoporous carbon CMK-3. In the three-electrode system, the specific capacitance of SPC-900 can reach 363 F g−1, whereas that of PC-900 is only 164 F g−1 at a current density of 0.5 A g−1. The double layer capacitance (EDLC) and pseudocapacitance can both be increased by the sulfur element, according to the capacitive contribution study. Additionally, the SPC-900 can maintain its initial specific capacitance of 98.1 % for 10,000 cycles at a current density of 0.5 A g−1, demonstrating both its high cycling performance and potential for practical applications.

Bidirectional enhancement of Li2S redox reaction by NiSe2/CoSe2-rGO heterostructured bi-functional catalysts

The high activity barriers of Li2S nucleation and deposition limit the redox reaction kinetics of lithium polysulfides (LiPSs), meanwhile, the significant shuttle effect of LiPSs hampers the advancement of Li-S batteries (LSBs). In this work, a NiSe2/CoSe2-rGO (NiSe2/CoSe2-G) sulfur host with bifunctional catalytic activity was prepared through a hard template method. Electrochemical experiment results confirm that the combination of NiSe2 and CoSe2 not only facilitates the bidirectional catalytic function during charge and discharge processes, but also increases the active sites toward LiPSs adsorption. Simultaneously, the highly conductive rGO network enhances the electronic conductivity of NiSe2/CoSe2-G/S and provides convenience for loading NiSe2/CoSe2 catalysts. Benefitting from the exceptional catalytic-adsorption capability of NiSe2/CoSe2 and the presence of rGO, the NiSe2/CoSe2-G/S electrode exhibits excellent electrochemical properties. At 1C, it demonstrates a low capacity attenuation of 0.087 % per cycle during 500 cycles. The electrode can maintain a discharge capacity of 927 mAh/g at a sulfur loading of 3.3 mg cm−2. The bidirectional catalytic activity of NiSe2/CoSe2-G offers a prospective approach to expedite the redox reactions of active S, meanwhile, this work also offers an ideal approach for designing efficient S hosts for LSBs.

Highly Active and Robust Catalyst: Co2B-Fe2B Heterostructural Nanosheets with Abundant Defects for Hydrogen Production.

A high-performance and reusable nonnoble metal catalyst for catalyzing sodium borohydride (NaBH4) hydrolysis to generate H2 is heralded as a nuclear material for the fast-growing hydrogen economy. Boron vacancy serves as a flexible defect site that can effectively regulate the catalytic hydrolysis performance. Herein, we construct a uniformly dispersed and boron vacancy-rich nonnoble metal Co2B-Fe2B catalyst via the hard template method. The optimized Co2B-Fe2B exhibits superior performance toward NaBH4 hydrolysis, with a high hydrogen generation rate (5315.8 mL min-1 gcatalyst-1), relatively low activation energy (35.4 kJ mol-1), and remarkable cycling stability, outperforming the majority of reported catalysts. Studies have shown that electron transfer from Fe2B to Co2B, as well as abundant boron defects, can effectively modulate the charge carrier concentration of Co2B-Fe2B catalysts. Density functional theory calculations confirm that the outer electron cloud density of Co2B is higher than that of Fe2B, among which Co2B with high electron cloud density can selectively adsorb BH4- ions, while the electron-deficient Fe2B is favorable for capturing H2O molecules, therefore synergistically promoting the catalytic NaBH4 hydrolysis to produce H2.

Design strategy for metal–organic framework assembled on modifications of MXene layers for advanced supercapacitor electrodes

The poor electronic conductivity and instability of metal–organic framework (MOFs) nanomaterials have been considered as the main reasons that hinder their practical application. Here, the bimetallic NiCo-MOF is in-situ grown by two-dimension expanded MXene to construct promising hierarchical electrodes. Benefitting from the hydroxyl group on the surface of MXene attracts metal (Ni, Co) ions by weak coordination, leading to oxygen vacancies during NiCo-MOF formation. At the same time, the density functional theory (DFT) calculation displays that the redox active center of NiCo-MOF is guaranteed to possess excellent electron and ion transport performance. Moreover, the open morphology based on expanded MXene by the hard template method can solve the re-stacking problem of MXene and provide a larger growth area for NiCo-MOF. The electrode design engineering strategy significantly improves the capacitance performance by increasing the electrochemically active site and promoting the ion dynamics. Specifically, the integrated solid-state hybrid supercapacitor (HSC) with MXene@NiCo-MOF and activated carbon (AC) exhibits energy density of 40.23 Wh·kg−1 at a power density of 1495.07 W·kg−1 and 84.4 % capacitance retention after 10,000 cycles via adopting this strategy. The strategy also provides a new route to improve the performance of flexible MXene-based supercapacitors with polyvinyl alcohol hydrogel electrolytes.

Recyclable fabrication of hollow N-doped amorphous carbon nanospindles with abundant short-range curved carbon fragments as bifunctional anode for lithium/sodium ion storage

A recyclable hard-template method is proposed to exploit spindle-shaped hollow nitrogen-doped amorphous carbon (h-NAC) with a large number of short-range curved carbon fragments as anodes for lithium/sodium ion batteries (LIBs/SIBs). Besides providing adsorption sites due to the high existence of oxygen-containing functional groups (CO and COOH), the heavily exposed edge regions also provide a favorable storage environment with high adsorption energy for Li+/Na+ due to their short-range curved structure. Importantly, the etching solution of hard templates can be recycled to generate the FeOOH nanospindles as a precursor through a simple chemical titration, which supplies a new idea for the green preparation of hollow materials. The h-NAC electrode is proven to be bifunctional for storing lithium and sodium ions, displaying favorable rate capability (255 mAh g−1 and 106 mAh g−1 at 5 A g−1 for LIBs and SIBs, respectively). After 1000 cycles at 1 A g−1, the reproducible capacities of the LIBs and SIBs kept 496 mAh g−1 and 181 mAh g−1, respectively.

Hollow structured CdS@ZnIn2S4 Z-scheme heterojunction for bifunctional photocatalytic hydrogen evolution and selective benzylamine oxidation

Photocatalytic hydrogen evolution (PHE) is frequently constrained by inadequate light utilization and the rapid combination rate of the photogenerated electron-hole pairs. Additionally, conventional PHE processes are often facilitated by the addition of sacrificial reagents to consume photo-induced holes, which makes this approach economically unfavorable. Herein, we designed a spatially separated bifunctional cocatalyst decorated Z-scheme heterojunction of hollow structured CdS (HCdS) @ZnIn2S4 (ZIS), which was prepared by a sacrificial hard template method followed by photo-deposition. Consequently, PdOx@HCdS@ZIS@Pt exhibited efficient PHE (86.38 mmol·g−1·h−1) and benzylamine (BA) oxidation coupling (164.75 mmol·g−1·h−1) with high selectivity (97.34 %). The unique hollow core-shelled morphology and bifunctional cocatalyst loading in this work hold great potential for the design and synthesis of bifunctional Z-scheme photocatalysts.

Porifera-Inspired Lightweight, Thin, Wrinkle-Resistance, and Multifunctional MXene Foam.

Transition metal carbides/nitrides (MXenes) demonstrate a massive potential in constructing lightweight, multifunctional wearable electromagnetic interference (EMI) shields for application in various fields. Nevertheless, it remains challenging to develop a facile, scalable approach to prepare the MXene-based macrostructures characterized by low density, low thickness, high mechanical flexibility, and high EMI SE at the same time. Herein, the ultrathin MXene/reduced graphene oxide (rGO)/Ag foams with a porifera-inspired hierarchically porous microstructure are prepared by combining Zn2+ diffusion induction and hard template methods. The hierarchical porosity, which includes a mesoporous skeleton and a microporous MXene network within the skeleton, not only exerts a regulatory effect on stress distribution during compression, making the foams rubber-like resistant to wrinkling but also provides more channels for multiple reflections of electromagnetic waves. Due to the interaction between Ag nanosheets, MXene/rGO, and porous structure, it is possible to produce an outstanding EMI shielding performance with the specific surface shielding effectiveness reaching 109152.4dBcm2 g-1 . Furthermore, the foams exhibit multifunctionalities, such as transverse Joule heating, longitudinal heat insulation, self-cleaning, fire resistance, and motion detection. These discoveries open up a novel pathway for the development of lightweight MXene-based materials with considerable application potential in wearable electromagnetic anti-interference devices.

Designed fabrication of MoS2 hollow structures with different geometries and the comparative investigation toward capacitive properties.

Hollow MoS2 cubes and spheres were synthesized by a one-step hydrothermal method with the hard template method. The structure and morphology were characterized, and their electrochemical properties were studied. It is concluded that the specific capacitance of the hollow MoS2 cubes (335.7 F g-1) is higher than that of the hollow MoS2 spheres (256.1 F g-1). The symmetrical supercapacitors were assembled, and the results indicate that the specific capacitance of the device composed of hollow MoS2 spheres (32.9 F g-1) is slightly lower than that of the hollow MoS2 cube (37.4 F g-1) device. Furthermore, the symmetrical supercapacitor (MoS2-cube//MoS2-cube) provides a maximum energy density of 4.93 W h kg-1, which is greater than that of the symmetrical capacitor (MoS2-sphere//MoS2-sphere, 3.65 W h kg-1). This may indicate that hollow molybdenum disulfide cubes with substructures have more efficient charge transfer capabilities and better capacitance characteristics than hollow spheres. After 8000 cycles, the coulombic efficiency of the two symmetrical capacitors is close to 100%. The capacity retention of the MoS2 sphere device (95.2%) is slightly higher than that of the MoS2 cube device (90.1%). These results show that the pore structure, specific surface, and active site of MoS2 with different hollow structures have a greater impact on its electrochemical properties.

Conductive V2O3 electrocatalyst on carbon hollow spheres to accelerate polysulfide conversion for long-cycle and high-rate lithium sulfur batteries

The V2O3/C-HS material was prepared by a hard template and impregnation method. When applied in lithium–sulfur batteries, it shows excellent long-cycle and high-rate performance.

Sustainable lignin-derived hierarchical mesoporous carbon synthesized by a renewable nano-calcium carbonate hard template method and its utilization in zinc ion hybrid supercapacitors

Research on zinc-ion hybrid supercapacitors has been gaining much attention due to the combination of their high energy and power density.

Tumor microenvironment responsive nano-platform for overcoming sorafenib resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor, which seriously jeopardizes human health. The 5-year relative survival rate of HCC is only about 18%. Sorafenib, a small molecule multi-targeted tyrosine kinase inhibitor (MTKI), has been classified as the first-line treatment scheme for HCC and has significantly extended the median survival time for patients with advanced HCC. Nevertheless, the emergence of sorafenib resistance has substantially hampered its further clinical application. Herein, the nano-platform based on phototherapy and small molecular targeted therapy (SMTT) was devised to overcome the sorafenib resistance and reduce the adverse effects. Hollow mesoporous manganese dioxide (H–MnO2) was prepared by hard template method, and the prepared H–MnO2 was used to load sorafenib and Chlorin e6 (Ce6). Subsequently, the nanoparticle (NPs) were modified with dopamine to optimize biocompatibility. The final prepared NPs (MCS NPs) exhibit regular spherical shape with a hydrated particle size of approximately 97.02 nm. MCS NPs can not only possess tumor microenvironment (TME) stimuli-responsive drug release performance but also can enhance the efficacy of photodynamic therapy and reverse sorafenib resistance by alleviating tumor hypoxia. Under the action of phototherapy (Ce6) combined with molecular targeted therapy (sorafenib), MCS NPs manifest a satisfactory antitumor effect for sorafenib-sensitive or sorafenib-resistant HCC cells, and retain the antiangiogenic properties of sorafenib. In the nude mouse subcutaneous tumor model constructed with sorafenib-resistant cells, MCS NPs demonstrated superior tumor imaging ability and excellent biocompatibility. The tumor inhibition rate of the MCS NPs group without laser irradiation was 53.4 %, while the MCS NPs group with laser irradiation was as high as 100 %. The novel smart TME-responsive nano-platform shows great potential for overcoming sorafenib resistance and realizes multimodality imaging and therapy of HCC.

Construction and performance evaluation of pH-responsive oxidized hyaluronic acid hollow mesoporous silica nanoparticles

In this study, hollow mesoporous silica (HMSN) was created to facilitate drug distribution using the hard template method. The oxidized hyaluronic acid (oxiHA) was coated on the carrier surface by the Schiff base reaction, producing the pH-responsive nanoparticles HMSNs-DOX-oxiHA targeted by CD44 and preventing drug leakage from mesopores. The prepared nanoparticles had a size of 151.79 ± 13.52 nm and a surface potential of −8.42 ± 0.48 mV. The rich mesoporous structure and internal cavity of HMSNs-NH2 achieved the effective encapsulation and loading rates of doxorubicin (DOX) at 76.84 ± 0.24 % and 18.73 ± 0.05 %, respectively. Owing to the pH sensitivity of imine bonds, HMSNs-DOX-oxiHA has a good pH response and release performance. The in vitro experiments showed that the nanoparticles were not cytotoxic and could enhance HCT-116 uptake efficiency by hyaluronic acid/CD44 receptor-mediated endocytosis, effectively inhibiting tumor cell proliferation and reducing toxic side effects on normal cells. In summary, the polysaccharide-based nano-drug delivery system constructed in this experiment not only has the basic response properties of a carrier but also introduces the bioactive advantages of natural polysaccharides.

Preparation and properties of mesoporous SiO2/polyimide composite films

AbstractAlthough polyimide films have a low dielectric constant, with the advent of the 5G era, the dielectric properties of the material are required to be further improved. Therein, we prepared controlled hollow mesoporous SiO2 nanomicrospheres by the hard template method to make mesoporous low dielectric polyimide films. The composite membrane exhibits better thermal stability, mechanical properties, and hydrophobicity compared to the pure membrane. Hollow mesoporous SiO2 dispersed in polyimide can reduce the inhomogeneity of charge distribution between molecules and reduce the interaction between polar chemical bonds and aromatic rings, thus improving the dielectric properties of the whole film. The minimum dielectric constant of the composite films was 2.80 when the hollow mesoporous SiO2 was added at 1.0%. These results fully indicate that the addition of hollow mesoporous SiO2 is beneficial to the multifaceted performance of the polyimide films.Highlights Preparation of hollow mesoporous SiO2 microspheres by using different polystyrene microsphere solutions and TEOS ratios. Synthesis of composite films with different contents of hollow mesoporous SiO2 as functional fillers. The effect of hollow mesoporous SiO2 content on the mechanical properties and thermal stability of PI composite films was investigated. Addition of hollow mesoporous SiO2 reduces the dielectric constant of polyimide composite films.