Pore-expanding Agent Research Articles

Zinc-ion hybrid supercapacitors with hierarchically N-doped porous carbon electrodes and ZnSO4/ZnI2 redox electrolyte exhibit boosted energy density

Zinc-ion hybrid capacitors (ZIHCs) with high energy density is commercial need as energy storing devices, but facile preparation is still a challenge. Herein, we proposed a combined strategy for preparation of ZIHCs with high performance. For this purpose, a nanoemulsion assembly approach with Pluronic F127 as structure-directing agent, 1, 3, 5-trimethylbenzene as pore-expanding agent, polydopamine as carbon and nitrogen source, was used to synthesize hierarchically N-doped porous carbon spheres (N-HNCSs). The optimized sample of N-HNCS-1 exhibited uniform size of 150 nm, hierarchically porous structure, large surface area (705.46 m2 g−1), and N-doping amount of 6.51 %. These properties were beneficial for the transportation of the electrolyte ions resulted in that the N-HNCS-1 electrode displayed superior electrochemical performance with specific capacity of 142 mAh g−1. Furthermore, the Zn//ZnSO4 + ZnI2//N-HNCS-1 ZIHCs achieves an exceptionally high energy density of 347.7 Wh kg−1, which is 3-fold higher than that of Zn//ZnSO4//N-HNCS-1 ZIHCs. To elucidate this outstanding performance, we investigate the mechanisms involved, including Zn2+ deposition/stripping, SO42-/I- adsorption/desorption, Zn4SO4(OH)6⋅0.5 H2O precipitation/dissolution, and redox reactions relating to iodine ions. The incorporation of ZnI2 redox-electrolyte significantly enhanced the energy density by providing prominent pseudocapacitance via the faradaic reaction. Therefore, the high performance of Zn//ZnSO4 + ZnI2//N-HNCS-1 ZIHCs is attributed to the introduction of nitrogen (N) species, advantageous 3D carbonaceous framework, and redox reactions triggered by adding zinc iodide (ZnI2) into the aqueous zinc sulfate (ZnSO4) electrolyte. This groundbreaking research opens up possibilities for the development of high-energy ZIHCs, and advancements in energy storage technology.

Ingeniously incorporating hollow mesoporous silica into waterborne polyurethane film to improve water vapor permeability

Incorporating hollow mesoporous silica (HMS) into waterborne polyurethane (WPU) to improve water vapor permeability (WVP) remains a major challenge. Herein, HMS-I and HMS-II with large hollow size and mesoporous structure were prepared with n-hexane as pore-expanding agent, and template was removed by calcination and extraction, respectively. Then, HMS/WPU composite emulsion was prepared by dispersing the pre-prepared polyurethane prepolymer terminated by 3-(aminopropyl)triethoxysilane (APTES) into aqueous medium containing HMS particles, with the help of co-condensation between silanol on HMS surface and silanol produced by Si-OEt hydrolysis of APTES. The results showed that the WVP of the composite film was greatly improved, especially HMS-II/WPU was better than HMS-I/WPU. This design strategy provides a prospect for the preparation and extensive application of HMS/WPU functional composites.

Synthesis and characterization of mesoporous-HZSM-5 as a catalyst for ethanol dehydration to ethylene

In this work, mesoporous HZSM-5 (M-HZSM-5) was synthesized with γ-(2,3-epoxypropoxy) propyltrimethoxysilane as pore-expanding agent through one-pot method and was studied for its catalytic activity and stability in ethanol dehydration. The resultant samples were characterized by various techniques, including Brunauer-Emmett-Teller, Scanning electron microscopy, Fourier transform infrared spectroscopy, the temperature-programmed desorption of NH3, and Thermogravimetric. Based on the analysis of the results, M-HZSM-5 with the typical MFI structure displays a specific surface area of 450 m2 g−1. Furthermore, the improvement of the activity and anti-coking ability of the catalyst for ethanol dehydration to ethylene is attributed to the existence of mesopores in HZSM-5, which can provide the reaction space and acid sites.

One-Pot Preparation of Benzotriazole-Modified Porous Silica for Durable UVA Absorption Ability.

The durable application of poly(butylene adipate-co-terephthalate) (PBAT) under atmospheric conditions is restricted by its poor ultraviolet (UV) stability. To improve the anti-aging capacity to UV radiation of the PBAT film, we describe a straightforward and highly producible synthesis of UV-resistant dendrimeric porous silica nanospheres (SiO2–HBT) by adding benzotriazole as a pore-expanding agent, more importantly demonstrating its detailed mechanism. Well-dispersed silica nanospheres are shown to offer the release property for benzotriazole triggered by UV and heat irradiation while durable UV protection due to the supplementary of benzotriazole in the PBAT matrix. With benzotriazole compensation, the halving period of elongation at break performance was extended from about 15 to 48 h. Combined with gel content and gel permeation chromatography analyses, it was inferred that the process of crosslinking resulting from Norrish I can be effectively minimized by the action of SiO2–HBT. The design of modified release strategy realizes the durable UV absorption ability of the hydroxyphenyl benzotriazole class of photostabilizers in particular but more generally highlights an important adding method that should be considered when utilizing a photostabilizer.

Hierarchically porous zeolitic imidazolate framework-8 with tunable mesostructure as Pickering interfacial catalyst

A new method was developed for the fabrication of hierarchically porous zeolitic imidazolate framework-8 (ZIF-8) as Pickering interfacial catalyst for boosting the efficiency of biphasic catalytic reaction. Hexadecyl trimethyl ammonium bromide (CTAB) and 1,3,5-trimethylbenzene (TMB) were utilized as soft template and pore-expanding agent to prepare the hierarchically porous ZIF-8 with tunable mesostructure. XRD and FTIR measurements were employed to show the structure of as-prepared ZIF-8 samples. Interestingly, the amphiphilic property of as-prepared ZIF-8 samples, which was important for the stability of as-formed Pickering emulsions, could be varied by only adjusting the ratio of CTAB/TMB. Optical micrographs of Pickering emulsion stabilized by the as-prepared ZIF-8 samples were also conducted to present the morphology of the formed emulsion droplet. Pickering emulsion system stabilized with the hierarchically porous ZIF-8 exhibited excellent performance in the yield and reaction rate for Knoevenagel condensation reaction. The recycle experiments were also investigated in the formed Pickering emulsion system for 5 times. The mechanism of hierarchically porous ZIF-8 as Pickering interfacial catalyst for Knoevenagel condensation reaction was proposed. • Hierarchically porous ZIF-8 was prepared with CTAB and TMB as soft template and pore-expanding agent. • The amphiphilic property of as-prepared ZIF-8 samples can be varied with the ratio of CTAB/TMB. • ZIF-8-I samples can be used as Pickering interfacial catalyst to form a Pickering emulsion. • ZIF-8-I samples exhibit excellent performance in the yield and reaction rate for Knoevenagel condensation.

Tailored Nanoarchitecturing of Microporous ZIF-8 to Hierarchically Porous Double-Shell Carbons and Their Intrinsic Electrochemical Property.

Mesostructured polydopamine (PDA) coating has been successfully achieved on the surface of zeolitic imidazolate framework-8 (ZIF-8) particles by incorporating Pluronic F127 (with a pore-expanding agent, 1,3,5-trimethylbenzene) as a pore-directing agent during dopamine polymerization. Upon pyrolysis at high temperatures, mesostructured PDA-coated ZIF-8 particles become hierarchically porous double-shell carbons (HPDCs) with a wide pore size distribution ranging from micro- and meso- to macropores. The formation of a hollow inner shell progresses initially with the shrinkage of ZIF-8 at the periphery where the interface interactions with mesostructured PDA exist, and then the subsequent disintegration of the ZIF-8 core at higher temperatures occurs. Our HPDCs prepared in this study feature physical and electrochemical advantages of hierarchically porous carbons such as high electrochemically accessible surface area, short diffusion distance, and high mass-transfer rate, thus demonstrating significantly improved ion diffusion and surface-enhanced high specific capacitance at high charge-discharge rates. HPDC5.0 therefore exhibits the capacitance retention of up to 76.7% from 1 to 10 A g-1 and maximum specific capacitance of 344.7 F g-1 at 1 mV s-1. It also possesses superior electrochemical stability with about 108% capacitance retention even after 10,000 consecutive cycles of galvanostatic charge-discharge at 10 A g-1.

Hierarchical Cs–Pollucite Nanozeolite Modified with Novel Organosilane as an Excellent Solid Base Catalyst for Claisen–Schmidt Condensation of Benzaldehyde and Acetophenone

Cs–pollucite can be a potential solid base catalyst due to the presence of (Si-O-Al)−Cs+ basic sites. However, it severely suffers from molecular diffusion and pore accessibility problems due to its small micropore opening. Herein, we report the use of new organosilane, viz. dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC), as a promising pore-expanding agent to develop the hierarchical structure in nanosized Cs–pollucite. In respect to this, four different amounts of TPOAC were added during the synthesis of hierarchical Cs–pollucite (CP-x, x = 0, 0.3, 1.0, or 2.0, where x is the molar ratio of TPOAC) in order to investigate the effects of TPOAC in the crystallization process of Cs–pollucite. The results show that an addition of TPOAC altered the physico-chemical and morphological properties of hierarchical Cs–pollucite, such as the crystallinity, crystallite size, pore size distribution, surface areas, pore volume, and surface basicity. The prepared solids were also tested in Claisen–Schmidt condensation of benzaldehyde and acetophenone, where 82.2% of the conversion and 100% selectivity to chalcone were achieved by the CP-2.0 catalyst using non-microwave instant heating (200 °C, 100 min). The hierarchical CP-2.0 nanocatalyst also showed better catalytic performance than other homogenous and heterogeneous catalysts and displayed a high catalyst reusability with no significant deterioration in the catalytic performance even after five consecutive reaction runs.

Monodisperse mesoporous La2O3 flakes for the synthesis of glycerol carbonate by efficiently catalyzing the transesterification of dimethyl carbonate with glycerol

Monodisperse mesoporous La2O3 flakes were prepared by hydrothermal methods using polyethylene glycol as pore-expanding agent, the catalyst exhibited better catalytic activity than normal La2O3 in the reaction of glycerol and dimethyl carbonate to produce glycerol carbonate. The influence of the molecular weight of polyethylene glycol and the mass ratio of La(NO3)3·6H2O/polyethylene glycol on the catalyst was investigated. The results showed that the morphology of La2O3 was remolded to porous flakes interestingly by the suitable type and dosage of pore-expanding agent, this change made the La2O3 catalyst particles have higher alkalinity, better crystallinity, larger specific surface area and good dispersion, which greatly improved the catalytic performance of the catalyst. In addition, the optimal reaction conditions were studied. As a result, the as-prepared porous La2O3 modified by polyethylene glycol-20000 showed excellent catalytic performance with high glycerol carbonate yield of 99.4% under the optimal reaction conditions as follows: the glycerol/dimethyl carbonate molar ratio was 1:5, the catalyst dosage was 5.0 wt% to glycerol, the reaction temperature was 85 °C and the reaction time was 0.5 h. The catalyst had outstanding stability after six cycle reactions with almost no loss of catalytic activity. Thereby, the catalyst was considered to possess the promising potential in industrial production for catalyzing glycerol to the high value-added chemical glycerol carbonate.

Influences of solvothermal-assisted crystallization process on the microstructure and properties of SiO2-W0.02TiO2.06 composite aerogels synthesized via ambient pressure drying

In this work, the influence of solvothermal crystallization processes on the microstructure, pore characteristic, and adsorption/photocatalysis of SiO2-W0.02TiO2.06 composite aerogels synthesized via ambient pressure drying have been investigated. It has been clarified that the composite aerogels prepared via solvothermal crystallization at 120 °C for 0.5 h and 180 °C for 3 h exhibited high-specific surface area (416–729 m2/g) and pore volume (2.26–2.70 cm3/g). With the increase of solvothermal crystallization temperature and time, the crystallinity of composite aerogels increased gradually, but excessive solvothermal crystallization time at higher temperature decreased the pore volume greatly. Furthermore, it is found that bacterial cellulose (BC) in the composite gel plays an important role in enhancing the pore volume and crystallization of the SiO2-W0.02TiO2.06 composite aerogels as a pore-expanding agent and structure-directing agent. The as-synthesized SiO2-W0.02TiO2.06 composite aerogels exhibited higher adsorption and removal efficiency for RhB than the commercial P25-TiO2, which can be ascribed to its high pore volume and specific surface area, as well as the synergistic action of adsorption and photocatalysis.

Immobilization and sustained release of cefalexin on MCF nano-mesoporous material

Mesocellular foams (MCF) silica nanometer mesoporous molecular sieve was successfully synthesized by hydrothermal route. This method used poly(ethylene glycol)-block-poly(propyl glycol)-block-poly(ethylene glycol) as template, tetraethyl orthosilicate as silica source and 1, 3, 5-trimethylbenzene as pore-expanding agent to prepare nano mesoporous MCF in acidic medium. The MCF mesoporous material was characterized by powder X-ray diffraction (XRD), infrared (IR) spectroscopy, low temperature nitrogen adsorption-desorption at 77 K, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The effects of pH, temperature, adsorbent dosage, cefalexin dosage and contact time on the immobilization of cefalexin were studied. Under the optimized conditions, MCF has the best effect on the drug immobilization. The maximum immobilization amount of cefalexin in MCF nano-mesoporous material is 498.8 mg/g. The behavior of adsorption of cefalexin by MCF belongs to multilayer heterogeneous adsorption, which accords with the Freundlich adsorption isotherm. In the adsorption process, all the ΔH0, ΔS0 and Gibbs free energy change ΔG0 are less than zero, indicating that the adsorption process is spontaneous, exothermic entropy decreasing reaction at ordinary temperature. Kinetic investigation showed that the adsorption process of cefalexin on MCF belongs to the pseudo-second-order kinetic process. The release laws of composite material cephalexin-MCF in the simulated body fluid, gastric and intestinal fluid were investigated, respectively. The maximum cumulative release rate in simulated body fluid was 99.4% at 18 h. The maximum cumulative release rate in the simulated gastric juice was 48.7% at 6 h and in the simulated intestinal fluid the maximum cumulative release rate of 61.9% was achieved at 8 h. These release processes satisfy the zero-order ordered kinetic process. Behavior of the adsorption of cefalexin by MCF belonged to multilayer heterogeneous adsorption, according with the Freundlich adsorption isotherm.Kinetic investigation showed that the adsorption process of cefalexin onto MCF belonged to the pseudo-second-order kinetic process.The maximum immobilization amount of cefalexin in MCF nano-mesoporous material was 498.8 mg/g.In the adsorption process, all the ΔH0, ΔS0 and Gibbs free energy change ΔG0 are less than zero, indicating that the adsorption process was spontaneous, exothermic entropy decreasing reaction at ordinary temperature.Good sustained release effect of cefalexin in MCF was achieved in simulated body fluid.

Preparation of core–shell mesoporous silica nanoparticles with bimodal pore structures by regrowth method

Core–shell structured mesoporous silica nanoparticles (MSNs) with different pore characteristics in the cores and shells have been prepared by the regrowth method. Adding a silica source to a dispersion of presynthesized silica–surfactant composite nanoparticles with two-dimensional hexagonal mesostructures results in regrowth in preference to generation of new particles. Core–shell MSNs with bimodal porosities are easily obtained by adding a pore-expanding agent, 1,3,5-trimethylbenzene, in either the core or shell formation step. Detailed characterization of the core–shell MSNs reveals that the shells consist of disordered arrangements of relatively large or small pores and that the pore sizes in the cores change when the shells formed. Core–shell MSNs will be useful for controlling the release rates of the encapsulated guest molecules and for protecting internal pores from being plugged by other species.

Study of the Influence of Pore Width on the Disposal of Benzene Employing Tunable OMCs

By employing SBA-15 as a hard template and boric acid as a pore-expanding agent, we synthesized a series of tunable ordered mesoporous carbons (OMCs) with high specific surface areas and large pore volumes. The synthesized OMCs were used as adsorbents for benzene disposal to explore the influence of pore width on the adsorption of benzene. The XRD and nitrogen adsorption results revealed that the pore sizes of OMCs were contracted at certain values, within the range of 3.4–7.7 nm. The adsorption results for benzene on the OMCs showed that there was a gradual decrease in adsorption potential as the pore size of the adsorbent material increased. In addition, an evaluation of the dynamic adsorption of benzene per unit surface area indicated that the adsorption behaviors were strongly influenced by the pore width of the adsorbent material.

Studies of Hg2+ adsorption and desorption by mesocellular foams silica

MCFs (mesocellular foams) silica, a mesoporous material, was synthesized by the hydrothermal method using tri-block copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic P123, EO20-PO20-EO20) as a structuring agent and 1, 3, 5-trimethylbenzene as a pore-expanding agent and the product was characterized by powder X-ray diffraction and scanning electron microscopy. The prepared MCFs was employed as the adsorbent for a study of the adsorption of Hg2+. The adsorptive experimental results showed that the optimal adsorptive conditions were: pH = 5.0, MCFs amount 0.10 g, temperature 20°C, and adsorption time 40 min, when the initial concentration of Hg2+ is 1.0 mg mL−1. The maximum adsorptive amount of Hg2+ was 124.5 mg Hg2+ g−1 MCFs. The desorption studies found that the best desorbing agent is 0.10 M hydrochloric acid. The highest desorption rate of 80.61 % could be reached at a desorption duration of 3 h. The cost of the adsorbent used in this study is lower than that of activated carbon with a higher value of application.

Mussel-inspired polydopamine coated mesoporous silica nanoparticles as pH-sensitive nanocarriers for controlled release

A novel pH-sensitive controlled release system is proposed by using mussel-inspired polydopamine (PDA) coated mesoporous silica nanoparticles (MSNs) as nanocarriers. MSNs with a large pore diameter are synthesized by using 1,3,5-trimethylbenzene as a pore-expanding agent and are modified with a PDA coating by virtue of oxidative self-polymerization of dopamine in neutral pH. PDA coated MSNs are characterized by FTIR, TEM, N₂ adsorption and XPS techniques. The PDA coating can work as pH-sensitive gatekeepers to control the release of drug molecules from MSNs in response to the pH-stimulus. Doxorubicin (DOX, an anticancer drug) can be released in the acid media and blocked in the neutral media.

Highly ordered mesoporous carbons as the support for Pt catalysts towards alcohol electrooxidation: The combined effect of pore size and electrical conductivity

Pt nanoparticles were successfully deposited on ordered mesoporous carbons (CMK-3) using a pulse microwave-assisted polyol method. CMK-3 with three different pore sizes, obtained by using boric acid as the pore-expanding agent, were adopted. The pore size was controlled to be 4.4, 6.1, and 6.7nm while the highly ordered structure was still maintained. With these different CMK-3 samples as the support, the particle size of Pt was identical, about 2nm. It was found that the electrochemical surface area was almost the same in these three cases and the alcohol electrooxidation activity was not increased but decreased a little along with the pore size increment. The increased pore size of CMK-3 had no obviously positive effect on easier mass transfer and then a better electrocatalytic activity. This could be attributed to the very good 3-D interconnection of the nanospacings of CMK-3 per se. Moreover, combined with the theoretical calculation and confirmed by alternative current impedance results, the electrical conductivity of CMK-3 was dramatically decreased along with the pore size increasing, which counteracted the beneficial effect from easier mass transfer in the case of bigger pore size. Based on the present and reported results, it hints that when the carbon skeleton of carbon materials is different, the modification skills are changed for improving their structure in order to make them suitable for electrocatalysts supports.

Synthesis and Characterization of Large Pore Size and Highly Ordered Mesoporous Molecular Sieve SBA-15

In this study, large pore size and highly ordered mesoporous molecular sieve SBA-15 was successfully synthesized in the acidic medium by using n-propanol as the pore-expanding agent, and tetraethyl orthosilicate (TEOS) as silicon source and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymer (P123 triblock copolymer) as a template agent. The samples were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Nitrogen Adsorption-Desorption. It is found that the particles of mesoporous molecular sieve SBA-15 have regular morphology and ordered pore structure, and also have high specific surface area, large pore size and pore volume.

Study on Pore Diameter Regulation of Thiol Functionalized Mesoporous Silica and Cu<sup>2+</sup> Adsorption Performance

New thiol modified mesoporous adsorbent with different pore sizes was synthesized by hydrothermal, with triblock copolymers pluronic (F127) and cetyltrimethyl ammonium bromide (CTMABr) functioned as the mixing template, 1,3,5-trimethylbenzene (TMB) functioned as pore-expanding agent. Adsorption performance of different pore sized mesoporous adsorbents was studied by treatment of Heavy metal Cu2+. Results showed that the optimum dosage was molar ratio of 1.5 between TMB and surfactant, and under that condition, the BET pore size was 6.554 nm and BET pore volume was 0.6134cm3/g. The adsorption of Cu2+ on mesoporous adsorbents fitted well to Redlich-Peterson isotherm equation, which indicated chemisorption was dominant in the process of heavy metal adsorption on the mesoporous adsorption and monomolecular layer adsorption took advantage. According to Langmuir equation, QL was 0.6210 mmol/g, and that demonstrated pore-expanding treatment could not only enlarge pore volume and diameter, but also effectively increase the contact area with heavy metals. Pore-expanded functionalized mesoporous silica could act as the optimal adsorbents for heavy metal adsorption.

Effect of Pore-size of Mesoporous SBA-15 on Adsorption of Bovine Serum Albumin and Lysozyme Protein

In this paper, the effects of pore-size of SBA-15 on the adsorption kinetics and equilibrium of large protein molecules Bovine serum albumin (BSA) and lysozyme (LYS) have been investigated. The mesoporous molecular sieve SBA-15 with six different pore sizes were synthesized with P123 triblock copolymer as the template agent, and 1,3,5-trimethylbenzene (TMB) and isopropyl alcohol as the pore-expanding agent. The samples were characterized by N 2 adsorption/desorption, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). It is found that BSA and LYS were adsorbed rapidly on SBA-15 materials with large pores. The BSA adsorption capacity of sieve with the pore diameter of 21.4 nm reached 500 mg·g −1 within 25 minutes. However, if the pore diameter was smaller than 14 nm, the BSA adsorption capacity of the sieve was only about 220 mg·g −1. The adsorption equilibrium data fits in the Langmuir model, where the coefficient of effective use of specific area of mesoporous molecular sieve was found to be 0.03, 0.18, 0.37 and 0.48, corresponding to the pore diameter of 10.1 nm, 13.2 nm, 15.4 nm and 21.4 nm, respectively. The equilibrium loading amount of LYS on SBA-15 materials with pore size of 15.4 nm could be up to 1000 mg·g −1. The coefficient of effective use of surface area of mesoporous molecular sieve with diameter of 3.9 nm, 7.4 nm, 10.1 nm, 13.2 nm and 15.4 nm was 0.10, 0.47, 0.56, 0.71 and 0.79, respectively. It is also noted that greater pore size of mesoporous molecular sieve would lead to a higher coefficient of effective use of surface area.