Fe Single Atom Catalysts Promoting Polysulfide Redox Reduction in Quantum Dot Photovoltaics.

Developing cost-effective and highly efficient photocathodes toward polysulfide redox reduction is highly desirable for advanced quantum dot (QD) photovoltaics. Herein, we demonstrate nitrogen doped carbon (N-C) shell-supported iron single atom catalysts (Fe-SACs) capable of catalyzing polysulfide reduction in QD photovoltaics for the first time. Specifically, Fe-SACs with FeN4 active sites feature a power conversion efficiency of 13.7% for ZnCuInSe-QD photovoltaics (AM1.5G, 100 mW/cm2), which is the highest value for ZnCuInSe QD-based photovoltaics, outperforming those of Cu-SACs and N-C catalysts. Compared with N-C, Fe-SACs exhibit suitable energy level matching with polysulfide redox couples, revealed by the Kelvin probe force microscope, which accelerates the charge transferring at the interfaces of catalyst/polysulfide redox couple. Density functional theory calculations demonstrate that the outstanding catalytic activity of Fe-SACs originates from the preferable adsorption of S42- on the FeN4 active sites and the high activation degree of the S-S bonds in S42- initiated by the FeN4 active sites.

Fabrication of Polypyrrole Hollow Nanospheres by Hard-Template Method for Supercapacitor Electrode Material.

Conducting polymers like polypyrrole, polyaniline, and polythiophene with nanostructures offers several advantages, such as high conductivity, a conjugated structure, and a large surface area, making them highly desirable for energy storage applications. However, the direct synthesis of conducting polymers with nanostructures poses a challenge. In this study, we employed a hard template method to fabricate polystyrene@polypyrrole (PS@PPy) core-shell nanoparticles. It is important to note that PS itself is a nonconductive material that hinders electron and ion transport, compromising the desired electrochemical properties. To overcome this limitation, the PS cores were removed using organic solvents to create hollow PPy nanospheres. We investigated six different organic solvents (cyclohexane, toluene, tetrahydrofuran, chloroform, acetone, and N,N-dimethylformamide (DMF)) for etching the PS cores. The resulting hollow PPy nanospheres showed various nanostructures, including intact, hollow, buckling, and collapsed structures, depending on the thickness of the PPy shell and the organic solvent used. PPy nanospheres synthesized with DMF demonstrated superior electrochemical properties compared to those prepared with other solvents, attributed to their highly effective PS removal efficiency, increased specific surface area, and improved charge transport efficiency. The specific capacitances of PPy nanospheres treated with DMF were as high as 350 F/g at 1 A/g. And the corresponding symmetric supercapacitor demonstrated a maximum energy density of 40 Wh/kg at a power density of 490 W/kg. These findings provide new insights into the synthesis method and energy storage mechanisms of PPy nanoparticles.

Synthesis of Mesoporous Tetragonal ZrO2, TiO2 and Solid Solutions and Effect of Colloidal Silica on Porosity.

Metal oxides possessing a large surface area, pore volume and desirable pore size provide more varieties and active industrial potentials. Nevertheless, it is very challenging to produce crystal metal oxides while keeping satisfactory porosity features, especially for ternary compositions. High temperature is usually needed to produce crystal metal oxides, which readily leads to the collapse of the pore structure. Herein, by employing a 'soft' dispersant agent and a hard silica template, ZrO2, TiO2 and Zr-Ti solid solutions having a tetragonal crystal structure are produced and the silica-leached materials are characterized from macroscopic to atomistic scales. The micron-sized particulate powders are composed of nanoscale 'building blocks', with crystallite sizes between ~8 and 21 nm. These polycrystalline ceramic powders exhibit a high specific surface area (up to ~200 m2·g-1) and pore volume (up to 0.5 cm3·g-1), with a pore size range of ~5-20 nm. Importantly, the Zr/Ti-O-Si-OH chemical bonds exist on the particle surface, with about two-thirds of the surface covered by silica. The hydroxyl groups can further post-graft organic ligands or directly associate with species. Synthesized mesoporous metal oxides are highly homogenous and could potentially be used in various applications because of their tetragonal structure and porosity features.

Imidazole-octyl mixed-mode stationary phase based on macroporous silica for the purification of ovomucoid and ovotransferrin.

A process-simplified hard template approach was established to synthesize the monodisperse macroporous silica microspheres with homogeneous structures by twice alkali-thermal treatment and calcination routes. Porous vinyl-functionalized polysesquioxane microspheres (V-PMSQ) were synthesized through a hydrolyzation-polycondensation method and used as templates. The template particles with large aperture and high pore volume were obtained by adjusting the pH value and reaction time of the twice alkali-thermal reaction. After calcination, monodisperse silica microspheres with an average pore size of 30 nm, homogeneous pore structures, and narrow particle size distribution were fabricated, which can be directly used as chromatographic matrices without classification. After that, a new reversed-phase/strong anion-exchange (RP/SAX) mixed-mode stationary phase Sil-S-VOIM was prepared by bonding the 1-vinyl-3-octyl-imidazole ligands to the above silica microspheres through a "thiol-ene" click reaction. The performance of the Sil-S-VOIM column was evaluated by one acidic protein (transferrin) and two basic proteins (lysozyme, α-chymotrypsin) and compared to a single imidazole-modified Sil-S-VIM column and an octyl-modified Sil-C8 column, respectively. Due to the synergistic effect of electrostatic repulsion and hydrophobic interactions, baseline separations of the above proteins were observed only on the Sil-S-VOIM column, with resolutions of 2.55 and 2.01 between lysozyme and transferrin, and between transferrin and α-chymotrypsin, respectively, indicating good selectivity and separation ability compared with single-mode stationary phases. It was applied to the isolation of egg white samples with peaks identified by SDS-PAGE and MALDI-TOF-MS. The results showed that the selective retention and isolation of ovomucoid and ovotransferrin were successfully achieved, with yields of 78.8% and 67.2%, respectively. The protocol described in this work is simpler, faster, and has higher protein recovery. Overall, this new mixed-mode stationary phase provided a promising potential for the separation and determination of intact proteins.

Tailoring the Morphology of Monodisperse Mesoporous Silica Particles Using Different Alkoxysilanes as Silica Precursors.

The hard template method for the preparation of monodisperse mesoporous silica microspheres (MPSMs) has been established in recent years. In this process, in situ-generated silica nanoparticles (SNPs) enter the porous organic template and control the size and pore parameters of the final MPSMs. Here, the sizes of the deposited SNPs are determined by the hydrolysis and condensation rates of different alkoxysilanes in a base catalyzed sol-gel process. Thus, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), tetrapropyl orthosilicate (TPOS) and tetrabutyl orthosilicate (TBOS) were sol-gel processed in the presence of amino-functionalized poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (p(GMA-co-EDMA)) templates. The size of the final MPSMs covers a broad range of 0.5-7.3 µm and a median pore size distribution from 4.0 to 24.9 nm. Moreover, the specific surface area can be adjusted between 271 and 637 m2 g-1. Also, the properties and morphology of the MPSMs differ according to the SNPs. Furthermore, the combination of different alkoxysilanes allows the individual design of the morphology and pore parameters of the silica particles. Selected MPSMs were packed into columns and successfully applied as stationary phases in high-performance liquid chromatography (HPLC) in the separation of various water-soluble vitamins.

Rapid Access to Ordered Mesoporous Carbons for Chemical Hydrogen Storage.

Ordered mesoporous carbon materials offer robust network of organized pores for energy storage and catalysis applications, but suffer from time-consuming and intricate preparations hindering their widespread use. Here we report a new and rapid synthetic route for a N-doped ordered mesoporous carbon structure through a preferential heating of iron oxide nanoparticles by microwaves. A nanoporous covalent organic polymer is first formed in situ covering the hard templates of assembled nanoparticles, paving the way for a long-range order in a carbonaceous nanocomposite precursor. Upon removal of the template, a well-defined cubic mesoporous carbon structure was revealed. The ordered mesoporous carbon was used in solid state hydrogen storage as a host scaffold for NaAlH4 , where remarkable improvement in hydrogen desorption kinetics was observed. The state-of-the-art lowest activation energy of dehydrogenation as a single step was attributed to their ordered pore structure and N-doping effect.

Nanocasting of Periodic Mesoporous Materials as an Effective Strategy to Prepare Mixed Phases of Titania.

Mesoporous titanium dioxide materials were prepared using a nanocasting technique involving silica SBA-15 as the hard-template. At an optimal loading of titanium precursor, the hexagonal periodic array of pores in SBA-15 was retained. The phases of titanium dioxide could be easily varied by the number of impregnation cycles and the nature of titanium alkoxide employed. Low number of impregnation cycles produced mixed phases of anatase and TiO2(B). The mesoporous TiO2 materials were tested for solar hydrogen production, and the material consisting of 98% anatase and 2% TiO2(B) exhibited the highest yield of hydrogen from the photocatalytic splitting of water. The periodicity of the pores was an important factor that influenced the photocatalytic activity. This study indicates that mixed phases of titania containing ordered array of pores can be prepared by using the nanocasting strategy.

Circularly polarized light emission and detection by chiral inorganic semiconductors.

Chiral inorganic semiconductors with high dissymmetric factor are highly desirable, but it is generally difficult to induce chiral structure in inorganic semiconductors because of their structure rigidity and symmetry. In this study, we introduced chiral ZnO film as hard template to transfer chirality to CsPbBr3 film and PbS quantum dots (QDs) for circularly polarized light (CPL) emission and detection, respectively. The prepared CsPbBr3/ZnO thin film exhibited CPL emission at 520 nm and the PbS QDs/ZnO film realized CPL detection at 780 nm, featuring high dissymmetric factor up to around 0.4. The electron transition based mechanism is responsible for chirality transfer.

A review on template-assisted approaches & self assembly of nanomaterials at liquid/liquid interface.

In recent times, nanomaterials (NMs) have gained significant attention for their unique properties and wide-ranging applications. This increased interest has driven research aimed at developing more efficient synthetic approaches in the fields of material science. Moreover, today's increasing demand for materials underscores the need for innovative technologies that can effectively scale up production to meet these growing needs. Hence, this review is primarily delve deeply into the template-assisted method i.e., an advance bottom-up approach for NMs synthesis. Furthermore, this review emphasizes to explore the advancements in soft template-based synthetic strategies for nanostructured materials as it provides high control on morphology and size. Therefore, this review specifically organized around on providing an in-depth discussion of the liquid/liquid interface-assisted soft template method, applications, and the factors affecting liquid/liquid interface for NMs synthesis. These key points are instrumental in driving advancements, highlighting the ongoing need for further enhancement and refinement of smart technologies. Finally, we conclude the review by describing the challenges and future perspectives of the liquid/liquid-assisted approach for NMs designing.

Revealing the Effect of the Microstructure on Potassium Storage Behavior in a Two-Dimensional Mesoporous Carbon Anode.

Hard carbon is considered as the most promising anode material for potassium-ion energy storage devices. Substantial progress has been made in exploring advanced hard carbons to solve the issues of sluggish kinetics and large volume changes caused by the large radius of K+. However, the relationship between their complicated microstructures and the K+ charge storage behavior is still not fully explored. Herein, a series of two-dimensional mesoporous carbon microcoins (2D-MCMs) with tunable microstructures in heteroatom content and graphitization degree are synthesized by a facile hard-template method and follow a temperature-controllable annealing process. It is found that high heteroatom content makes for surface-driven K+ storage behavior, which increases the capacity-contribution ratio from a high potential region, while a high graphitization degree makes for K+ intercalation behavior, which increases the capacity-contribution ratio from a low potential region. Electrochemical results from a three-electrode Swagelok cell demonstrate that a 2D-MCM anode with more capacity contribution from a low working region allows the porous carbon cathode to be operated in a much wider electrochemical window, thus storing more charge. As a result, potassium-ion capacitors based on the optimized 2D-MCM anode deliver a high energy density of 113 Wh kg-1 and an exhilarating power density of 51,000 W kg-1.

Metal-Support Interaction in Pt Nanodisk-Carbon Nitride Catalyst: Insight from Theory and Experiment.

Metal-support interaction plays a critical role in determining the eventual catalytic activity of metals loaded on supporting substrates. This interaction can sometimes cause a significant drop in the metallic property of the loaded metal and, hence, a drop in catalytic activity in the reactions, especially in those for which low charge carrier transfer resistance is a necessary parameter. Therefore, there should be a case-by-case experimental or theoretical (or both) in-depth investigation to understand the role of support on each metal. Here, onto a layered porous carbon nitride (g-CN), we grew single crystalline Pt nanodisks (Pt@g-CN) with a lateral average size of 21 nm, followed by various characterisations such as electron microscopy techniques, and the measurement of electrocatalytic activity in the O2 reduction reaction (ORR). We found that intercalating Pt nanodisks in the g-CN interlayers causes an increase in electrocatalytic activity. We investigated the bonding mechanism between carbon support and platinum using density functional theory and applied the d-band theory to understand the catalytic performance. Analysis of Pt's density of states and electronic population across layers sheds light on the catalytic behaviour of Pt nanoparticles, particularly in relation to their thickness and proximity to the g-CN support interface. Our simulation reveals an optimum thickness of ~11 Å, under which the catalytic performance deteriorates.

In-situ synthesis of porous Na3V2(PO4)3 with stable VOC bridge bonding by hard template method.

Low electronic conductivity and poor properties at high rate have hindered the application of Na3V2(PO4)3 (NVP). Herein, a facile synthesis of NVP with porous carbon skeleton is proposed. Specifically, Na2CO3 and glucose, acting as hard templates, are introduced to the precursors after initial firing stage, and Na2CO3 particles are removed by flushing after the final heatment. Due to the thermal conductivity of Na2CO3, the secondary addition of glucose can generate distinctive graphitized porous carbon skeleton, which bonds well with the amorphous carbon coating to construct stable and conductive network. The porous construction can alleviate the stress and strain caused by the current impact through deformation. Furthermore, ex-situ EIS reveals the highly conductive carbon skeleton can significantly reduce the surface resistance and result in an increase of effective voltage to promote the de-intercalation of Na+. Moreover, the ex-situ X-ray photoelectron spectroscopy (XPS) at different potentials confirms the stabilized existence of VOC bonds. Benefiting from the unique carbon skeleton, the PC-NVP releases capacity of 116.9 mAh g-1 at 0.1C. Even at 120C, PC-NVP still exhibits a high capacity of 84.7 mAh g-1, retaining a value of 41.3 mAh g-1 after 16,000 cycles, corresponding to a low decay rate of 0.0032% per cycle.

The Fig-Like hierarchical Double-Shelled hollow TiN particles as sulfur host for Lithium-Sulfur batteries.

Lithium-sulfur battery(LSB)'s commercial manufacturing has been mainly retarded by the "shuttle effect" and low electrical conductivity of polysulfides (LiPSs). Designing a cathode with hollow and hierarchically porous structures was expected to solve the above problems. Herein, a kind of TiN particles with the hierarchical hollow double-shelled structures was synthesized and applied to cathodes of LSB. The Fig-like hollow TiO2 particles (FHTiO2s) were firstly synthesized by the hard-template method. Subsequently, the Fig-like hierarchical hollow double-shelled TiN particles (FHTiNs) were synthesized by the template-free sequential transformation and separation approach (STSA). It was verified that the heating temperature and time were key parameters. Special Fig-like double-shell hollow structures could greatly increase the loading of S, and the excellent initial capacity of FHTiNs cathodes was up to 1159 mAh/g. On the one hand, the Fig-like framework in internal cavity and double-shell structures could promote the ultrahigh specific surface area, and the adsorption to LiPSs was improved by increasing active sites; On the other hand, the shuttle effect of LiPSs was weakened by the fig-like framework and double-shell structures, which slowed down the massive dissolution of sulfur in the electrolyte. As a result, the pleasant rate performance of FHTiNs cathodes was up to 400 mAh/g at 5C. This novel structures and synthesis method provided a new strategy for the designing of LSB cathodes.

Two-Dimensional V2O5 Inverse Opal: Fabrication and Electrochromic Application.

The open-layered structure of Vanadium pentoxide (V2O5) has triggered significant interest in exploring its energy-related application as lithium (Li) intercalation cathode material. Various methods are extensively studied to improve the Li diffusion using thin films or nanoarchitecture. In this work, high-quality two-dimensional (2D) inverse opal α-V2O5 films were synthesized via a modified 'dynamic hard template' infiltration strategy using sacrificial polystyrene spheres (PS, a diameter of 530 nm) photonic crystal as a template. The new material exhibited an excellent porous array with featured structural colors in a large area. The electrochromic behavior was explored by combining bandgap and electrochemical characterization. On the one hand, the intercalation/deintercalation of Li+ played an important role in the bandgap (Eg), and thereafter on the visible range transmittance through changing the film's stoichiometry and the valence of vanadium ions. On the other hand, the asymmetry of the lattice due to the disordered distribution of Li+ within the V2O5 interlayer and/or the formation of an irreversible phase explained the change in transmittance with voltage.

Equilibrium, Kinetic, and Thermodynamic Studies on Adsorption of Rhodamine B from Aqueous Solutions Using Oxidized Mesoporous Carbons.

Oxidized mesoporous carbon CSBA-15, obtained by the hard method, was applied to remove rhodamine B from the aqueous system. The process of carbon oxidation was performed using 0.5 and 5 M of nitric (V) acid solution at 70 and 100 °C. Functionalization of mesoporous carbon with HNO3 solutions led to reduction in the surface area, pore volume, and micropore area, however, it also led to an increased number of oxygen functional groups of acidic character. The functional groups probably are located at the entrance of micropores, in this way, reducing the values of textural parameters. Isotherms of rhodamine B adsorption indicate that the oxidation of mesoporous carbons resulted in an increase in the effectiveness of the removal of this dye from aqueous solutions. The influence of temperature, pH, and contact time of mesoporous material/rhodamine B on the effectiveness of dye removal was tested. The process of dye adsorption on the surfaces of the materials studied was established to be most effective at pH 12 and at 60 °C. Kinetic studies of the process of adsorption proved that the equilibrium state between the dye molecules and mesoporous carbon materials is reached after about 1 h. The adsorption kinetics were well fitted using a pseudo-second-order model. The most effective in rhodamine B removal was the sample CSBA-15-5-100, containing the greatest number of oxygen functional groups of acidic character. The Langmuir model best represented equilibrium data.

FeCoNi Ternary Nano-Alloys Embedded in a Nitrogen-Doped Porous Carbon Matrix with Enhanced Electrocatalysis for Stable Lithium-Sulfur Batteries.

The application of composite materials that combine the advantages of carbonaceous material and metal alloy proves to be a valid method for improving the performance of lithium-sulfur batteries (LSBs). Herein iron-cobalt-nickel (FeCoNi) ternary alloy nanoparticles (FNC) that spread on nitrogen-doped carbon (NC) are obtained by a strategy of low-temperature sol-gel followed by annealing at 800 °C under an argon/hydrogen atmosphere. Benefiting from the synergistic effect of different components of FNC and the conductive network provided by the NC, not only can the "shuttle effect" of lithium polysulfides (LiPS) be suppressed, but also the conversion of LiPS, the diffusion of Li+, and the deposition of Li2S can be accelerated. Taking advantage of those merits, the batteries assembled with an FNC@NC-modified polypropylene (PP) separator (FNC@NC//PP) can deliver a high reversible specific capacity of 1325 mAh g-1 at 0.2 C and maintain 950 mAh g-1 after 200 cycles, and they can also achieve a low capacity fading rate of 0.06% per cycle over 500 cycles at 1 C. More impressively, even under harsh test conditions (the ratio of electrolyte to sulfur (E/S) = 6 µL mg-1 and sulfur loading = 4.7 mg cm-2 and E/S = 10 µL mg-1 and sulfur loading = 5.9 mg cm-2), the area capacity of batteries is still much higher than 4 mAh cm-2.

Hollow Silica Nano and Micro Spheres with Polystyrene Templating: A Mini-Review.

Synthesis of monodisperse hollow silica nanospheres, especially using a hard template route, has been shown to be successful, but a high yield is needed for this strategy to be used on an industrial scale. On the other hand, there is a research gap in the synthesis of hollow silica microspheres due to the popularity and easiness of the synthesis of silica nanospheres despite the larger spheres being beneficial in some fields. In this review, current trends in producing hollow silica nanospheres using hard templates, especially polystyrene, are briefly presented. Soft templates have also been used to make highly polydisperse hollow silica spheres, and complex designs have improved polydispersity. The effect of the main parameters on the coating is presented here to provide a basic understanding of the interactions between the silica and template surface in the absence or presence of surfactants. Surface charge, surface modification, parameters in the sol-gel method and interaction between the silica and templates need to be further improved to have a uniform coating and better control over the size, dispersity, wall thickness and porosity. As larger organic templates will have lower surface energy, the efficiency of the micro sphere synthesis needs to be improved. Control over the physical structure of hollow silica spheres will open up many opportunities for them to be extensively used in fields ranging from waste removal to energy storage.

One-pot hard template synthesis of mesoporous spinel nanoparticles as efficient catalysts for low temperature CO oxidation.

Co-Fe, Cu-Cr, and Co-Mn mixed oxide catalysts were prepared using a one-pot hard template synthesis method, and their catalytic performance was investigated before and after the rearrangement of the template. To evaluate the structural properties of the catalysts, various analyses were employed, including the BET, XRD, H2-TPR, FE-SEM, EDX, and X-ray digital mapping of the elements. The results indicated that the rearrangement of the catalyst structure had a profound effect on the structural and catalytic properties, so that in all three synthesized catalysts, the specific surface and the reducibility increased significantly, and the crystalline structure and morphology of the catalysts changed remarkably. The specific surface area of the CoFe, CuCr, and CoMn catalysts increased from 3.5, 1.1, and 72.9 m2/g to 151.3, 52.8, and 108.0 m2/g, respectively. These structural changes significantly increased the catalytic performance. The results indicated that the 100% conversion temperature of the CoMn catalyst as the optimal sample after rearrangement was reduced from 250 to 125 °C. Also, the stability of the CoMn catalyst in dry and wet conditions was investigated and the results indicated that the presence of water vapor reduced the activity and stability of the catalyst. The activation energy was also calculated on Co-Mn catalyst (59.5 kJ/mol) and the results confirmed that the most probable mechanism for this reaction was the MVK mechanism.

Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as a hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal the effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure, which drastically improves catalytic performance.

Overcoming the paracetamol dose challenge with wrinkled mesoporous carbon spheres.

Paracetamol is the most commonly used antipyretic and analgesic drug in the world. The key challenge in paracetamol therapy is associated with the frequency of the dosing. Depending on the gastric filling within 10-20 min paracetamol is released and rapidly absorbed from the gastrointestinal tract. Therefore, it must be taken three or four times a day. To address the dose challenge it is desirable that the paracetamol release profile follows the zero-order kinetic model (constant rate of drug release per unit time). This goal can be achieved by using a suitable porous carrier system. Herein, non-toxic wrinkled mesoporous carbons with unique morphology were synthesized via the hard template method as new carriers for paracetamol. These particles can precisely modulate the release of paracetamol over 24 h in a simulated gastric fluid according to the zero-order kinetic model completely eliminating the initial burst release. Overall, these systems could significantly enhance the bioavailability of paracetamol and prolong its therapeutic effect in numerous diseases such as cold, flu, COVID-19, and severe pain.