红外宽频吸收硅基复合气凝胶的制备及表征

以正硅酸乙酯为硅源,采用酸碱两步催化法经过溶胶-凝胶和冷冻干燥制备出SiO2气凝胶基材,并在凝胶老化过程中添加三乙胺盐酸盐得到兼具中远红外吸收特性的硅基复合气凝胶。利用X射线衍射、扫描电子显微镜、氮吸附-脱附和傅里叶红外吸收光谱对气凝胶的结构和性能进行了表征。结果表明:胺盐在硅气凝胶网络结构中穿插结晶;基材的比表面积、最大孔容和平均孔径分别为524.5 m2/g、1.2 cm3/g和9.2 nm,复合材料的比表面积、最大孔容和平均孔径分别为37.93~138.7 m2/g、0.08~0.28 cm3/g和7.1~8.8 nm;基材和复合气凝胶的表观密度分别为0.25 g/cm3和0.35~0.51 g/cm3;复合气凝胶在中远红外窗口具有宽频吸收的特性,且三乙胺盐酸盐含量的增加,中红外相对吸收强度成比例增强。     

红外宽频吸收硅基复合气凝胶的制备及表征

以正硅酸乙酯为硅源,采用酸碱两步催化法经过溶胶-凝胶和冷冻干燥制备出SiO2气凝胶基材,并在凝胶老化过程中添加三乙胺盐酸盐得到兼具中远红外吸收特性的硅基复合气凝胶。利用X射线衍射、扫描电子显微镜、氮吸附-脱附和傅里叶红外吸收光谱对气凝胶的结构和性能进行了表征。结果表明:胺盐在硅气凝胶网络结构中穿插结晶;基材的比表面积、最大孔容和平均孔径分别为524.5 m2/g、1.2 cm3/g和9.2 nm,复合材料的比表面积、最大孔容和平均孔径分别为37.93~138.7 m2/g、0.08~0.28 cm3/g和7.1~8.8 nm;基材和复合气凝胶的表观密度分别为0.25 g/cm3和0.35~0.51 g/cm3;复合气凝胶在中远红外窗口具有宽频吸收的特性,且随着三乙胺盐酸盐含量的增加,中红外相对吸收强度成比例增强。     

氧化石墨烯掺杂二氧化硅气凝胶的特性研究

为满足高温防护需求,快速制备高强度、低导热系数的气凝胶成为一项重要的科学挑战。采用超临界干燥法,成功通过掺杂氧化石墨烯(GO)的方式,改善了二氧化硅气凝胶的性能。通过电子显微镜观察发现,GO均匀地镶嵌在气凝胶基体中,形成了有效的支撑骨架,显著增强了气凝胶的强度。傅立叶变换红外光谱分析表明,GO与二氧化硅气凝胶之间仅存在物理结合,并未形成明显的化学键。通过氮吸附/解吸测量发现,GO/SiO₂气凝胶的比表面积和孔径可以通过调整GO的用量进行可控调节。实验结果显示,当GO含量为质量分数0.5%,1%和2%时,GO/SiO₂气凝胶的比表面积分别为895,1294和997 m²/g,与未掺杂的SiO₂气凝胶(852 m²/g)相比有所增加。由于GO的加入,GO/SiO₂气凝胶的密度(0.07 g/cm³)略高于纯SiO₂气凝胶(0.06 g/cm³),为其提供了更高的强度和承载能力。此外,GO/SiO...     

改性活性炭双电层电容器电极材料研究

用氢氧化钾对普通活性炭活化改性,比表面积和总孔容由806m2/g和0.411cm3/g分别增加到1168m2/g和0.577cm3/g。用该材料制成硬币型双电层电容器,经测定炭材料比电容高达203.5F/g,提高了64%;等效串联内阻仅为1.94?,大电流放电时容量衰减小于10%。其突出优点是体积与面积比电容高达109.6F/cm3和17.4×10–6F/cm2。研究发现孔径分布于1.4～2.78nm的超微孔和小中孔,有利于电解质离子形成双电层而提高炭材料的电容量。     

复合活化剂组分质量比对活性炭微球电容性能的影响

为了制备高体积比电容活性炭微球(AMCMB),以KOH/NaOH为复合活化剂,在850℃下对中间相沥青微球(MPMB)进行活化处理。考察了KOH/NaOH复合活化剂不同组份质量比对AMCMB收率、振实密度及比电容的影响。结果表明:随着NaOH含量的增加,AMCMB的比电容呈现先增加后减小的趋势,并在质量比ζ(KOH:NaOH)=5:1时达到最大值81F/cm3,其孔径以微孔为主,中孔含量较高,平均孔径约为2.21nm,比表面积达2788m2/g,适合用作超级电容器电极材料。     

聚乙二醇含量对纳米TiO2多孔薄膜性质的影响

以钛酸丁酯为无机原料、二乙醇胺作稳定剂,加入聚乙二醇(PEG)作模板制备前驱体溶胶,通过溶胶-凝胶工艺和浸渍提拉技术在玻璃基片上制备了孔径在10～1000nm范围内可调的纳米TiO2多孔薄膜.通过ESEM,AFM,UV-VIS,N2吸附,XPS和XRD等测试手段研究了PEG(1000)的加入量对薄膜结构及性能的影响.结果表明,当100mL溶胶中PEG的加入量在4.0g左右时,可以得到三维扩展的多孔结构,孔的形状规则且分布均匀,孔径为200～500nm,薄膜比表面积可达76.1m2/g,而过多的PEG加入量反而导致薄膜性能下降.     

有序介孔炭的合成及电容性能研究

以蔗糖为前驱体,SBA—15介孔分子筛为模板合成了有序介孔炭(OMC)。研究了OMC的结构及电容性能。结果显示:OMC具有二维六方(P6mm)有序结构,比表面积为1046m2/g,孔径为3.7nm,孔容为1.27cm3/g,在1mol/L的硫酸溶液中有良好的电容特性。在充放电电流密度为200mA/g时,OMC比容量达到127.2F/g,当电流密度增大到1200mA/g时,其比容量仍维持在109.8F/g,能够满足快速充放电的要求。较之普通活性炭,OMC的时间常数从10s缩短为5s,高频电容特性和功率性能优异。     

聚乙二醇含量对纳米TiO2多孔薄膜性质的影响

以钛酸丁酯为无机原料、二乙醇胺作稳定剂,加入聚乙二醇（PEG）作模板制备前驱体溶胶,通过溶胶-凝胶工艺和浸渍提拉技术在玻璃基片上制备了孔径在10～1000nm范围内可调的纳米TiO2多孔薄膜．通过ESEM,AFM,UV-VIS,N2吸附,XPS和XRD等测试手段研究了PEG（1000）的加入量对薄膜结构及性能的影响．结果表明,当100mL溶胶中PEG的加入量在4.0g左右时,可以得到三维扩展的多孔结构,孔的形状规则且分布均匀,孔径为200～500nm,薄膜比表面积可达76.1m2／g,而过多的PEG加入量反而导致薄膜性能下降．     

超电容器活性炭/炭黑复合电极电容特性研究

为制备实用化的超电容器,对活性炭材料进行了表征,详细描述了活性炭/炭黑复合电极的制备工艺。通过循环伏安法和恒电流充电法,对活性炭/炭黑复合电极在水系电解液中的电容行为进行了研究。结果表明:活性炭的BET比表面积达1 654 m2/g,具有合理的孔径分布,主要在2 nm附近。添加高比表面积、高导电性纳米级炭黑制备的活性炭/炭黑复合电极具有优良的电容行为和较好的功率特性,复合电极的比容量达到102.4 F/g。此外还对孔径分布与电容的关系进行了阐述。     

无机络合溶胶-凝胶法制备多孔ZnO薄膜

利用无机络合溶胶-凝胶法制备多孔ZnO薄膜,同时利用多种测试手段对薄膜的晶体结构、表面形貌、多孔和光学性能进行了研究.XRD和SEM的测试结果表明,ZnO薄膜的晶体结构为六方纤锌矿,薄膜表面呈多孔状.由孔径分布曲线得出薄膜的孔主要集中在介孔2.02nm和4.97nm;500℃煅烧得到的ZnO薄膜的比表面积是27.57m2/g;在不同温度下煅烧的薄膜在可见光区域透射率均高于85%,光学带宽为3.25eV.     

Highly Elastic and Conductive N‐Doped Monolithic Graphene Aerogels for Multifunctional Applications

The simple synthesis of ultralow‐density (≈2.32 mg cm^?3) 3D reduced graphene oxide (rGO) aerogels that exhibit high electrical conductivity and excellent compressibility are described herein. Aerogels are synthesized using a combined hydrothermal and thermal annealing method in which hexamethylenetetramine is employed as a reducer, nitrogen source, and graphene dispersion stabilizer. The N‐binding configurations of rGO aerogels increase dramatically, as evidenced by the change in pyridinic‐N/quaternary‐N ratio. The conductivity of this graphene aerogel is ≈11.74 S m^?1 at zero strain, whereas the conductivity at a compressive strain of ≈80% is ≈704.23 S m^?1, which is the largest electrical conductivity reported so far in any 3D sponge‐like low‐density carbon material. In addition, the aerogel has excellent hydrophobicity (with a water contact angle of 137.4°) as well as selective absorption for organic solvents and oils. The compressive modulus (94.5 kPa; ρ ≈ 2.32 mg cm^?3) of the rGO aerogel is higher than that of other carbon‐based aerogels. The physical and chemical properties (such as high conductivity, elasticity, high surface area, open pore structure, and chemical stability) of the aerogel suggest that it is a viable candidate for the use in energy storage, electrodes for fuel cells, photocatalysis, environmental protection, energy absorption, and sensing applications.     

Patterned Carbon Nitride–Based Hybrid Aerogel Membranes via 3D Printing for Broadband Solar Wastewater Remediation

Controlled scalable assembly of 2D building blocks into macroscopic 3D architectures is highly significant. However, the assembly of g‐C₃N₄ into tailored, 3D architectures is not yet reported. Here, a 3D printing methodology to enable the programmable construction of carbon nitride–based hybrid aerogel membranes with patterned macroscopic architectures is proposed. g‐C₃N₄ nanosheets (CNNS) are used as the building block, and sodium alginate (SA) increases the viscosity of the ink to obtain the desired rheological properties. Three printing routes, including printing directly in air and in the supporting reservoirs composed of CaCl₂/glycerol solution or Pluronic F127, are demonstrated for printing versatility. The printed Au nanobipyramid–CNNS–SA hybrid aerogels exhibit broadband visible‐light absorption and superior solar wastewater remediation performance with excellent cyclic stability and easy manipulation features. Remarkably, the activity of the 3D‐printed aerogel is about 2.5 times of that of the contrast sample, attributing to the enhanced liquid velocity and solution diffusion efficiency because of the 3D‐printed structure, which is demonstrated by experimental and theoretical simulations. This approach can be extended to the macroscopic assembly of other 2D materials for myriad applications.     

Cellulose II Aerogel‐Based Triboelectric Nanogenerator

Cellulose‐based triboelectric nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose‐based aerogels and such aerogels are used to fabricate TENGs that can serve as mechanical energy harvesters and self‐powered sensors. The cellulose II aerogel is fabricated via a dissolution–regeneration process in a green inorganic molten salt hydrate solvent (lithium bromide trihydrate), where. The as‐fabricated cellulose II aerogel exhibits an interconnected open‐pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m² g^?1. Given its architectural merits, the cellulose II aerogel‐based TENG presents an excellent mechanical response sensitivity and high electrical output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron‐donating and electron‐withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelectric performance of the TENG. The cellulose II aerogel‐based TENG is demonstrated to light up light‐emitting diodes, charge commercial capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high‐performance and eco‐friendly energy harvesting and self‐powered system.     

Lightweight,Superelastic, and Hydrophobic Polyimide Nanofiber /MXene Composite Aerogel for Wearable Piezoresistive Sensor and Oil/Water Separation Applications

Inspired by the ultralight and structurally robust spider webs, flexible nanofibril-assembled aerogels with intriguing attributes have been designed for achieving promising performances in various applications. Here, conductive polyimide nanofiber (PINF)/MXene composite aerogel with typical “layer-strut” bracing hierarchical nanofibrous cellular structure has been developed via the freeze-drying and thermal imidization process. Benefiting from the porous architecture and robust bonding between PINF and MXene, the PINF/MXene composite aerogel exhibits an ultralow density (9.98 mg cm⁻³), intriguing temperature tolerance from -50 to 250 °C, superior compressibility and recoverability (up to 90% strain), and excellent fatigue resistance over 1000 cycles. The composite aerogel can be used as a piezoresistive sensor, with an outstanding sensing capacity up to 90% strain (corresponding 85.21 kPa), ultralow detection limit of 0.5% strain (corresponding 0.01 kPa), robust fatigue resistance over 1000 cycles, excellent piezoresistive stability and reproductivity in extremely harsh environments. Furthermore, the composite aerogel also exhibits superior oil/water separation properties such as high adsorption capacity (55.85 to 135.29 g g⁻¹) and stable recyclability due to its hydrophobicity and robust hierarchical porous structure. It is expected that the designed PINF/MXene composite aerogel can supply a new multifunctional platform for human bodily motion/physical signals detection and high-efficient oil/water separation.     

Flexible,Highly Graphitized Carbon Aerogels Based on Bacterial Cellulose/Lignin: Catalyst‐Free Synthesis and its Application in Energy Storage Devices

Currently, most carbon aerogels are based on carbon nanotubes (CNTs) or graphene, which are produced through a catalyst‐assisted chemical vapor deposition method. Biomass based organic aerogels and carbon aerogels, featuring low cost, high scalability, and small environmental footprint, represent an important new research direction in (carbon) aerogel development. Cellulose and lignin are the two most abundant natural polymers in the world, and the aerogels based on them are very promising. Classic silicon aerogels and available organic resorcinol–formaldehyde (RF) or lignin–resorcinol–formaldehyde (LRF) aerogels are brittle and fragile; toughening of the aerogels is highly desired to expand their applications. This study reports the first attempt to toughen the intrinsically brittle LRF aerogel and carbon aerogel using bacterial cellulose. The facile process is catalyst‐free and cost‐effective. The toughened carbon aerogels, consisting of blackberry‐like, core–shell structured, and highly graphitized carbon nanofibers, are able to undergo at least 20% reversible compressive deformation. Due to their unique nanostructure and large mesopore population, the carbon materials exhibit an areal capacitance higher than most of the reported values in the literature. This property makes them suitable candidates for flexible solid‐state energy storage devices. Besides energy storage, the conductive interconnected nanoporous structure can also find applications in oil/water separation, catalyst supports, sensors, and so forth.     

Multifunctional Superelastic Cellulose Nanofibrils Aerogel by Dual Ice-Templating Assembly

A superelastic aerogel with fast shape recovery performance from large compressive strain is highly desired for numerous applications such as thermal insulation in clothing, high-sensitive sensors, and oil contaminant removal. Fabrication of superelastic cellulose nanofibrils (CNF) aerogels is challenging as the CNF can assemble into non-elastic sheet-like cell walls. Here, a dual ice-templating assembly (DITA) strategy is proposed that can control the assembly of CNF into sub-micrometer fibers by extremely low temperature freezing (–196 °C), which can further assemble into an elastic aerogel with interconnected sub-micron fibers by freezer freezing (−20 °C) and freeze drying. The CNF aerogel from the DITA process demonstrates isotropic superelastic behavior that can recover from over 80% compressive strain along both longitudinal and cross-sectional directions, even in an extremely cold liquid nitrogen environment. The elastic CNF aerogel can be easily modified by chemical vapor deposition of organosilane, demonstrating superhydrophobicity (164° water contact angle), high liquid absorption (489 g g⁻¹ of chloroform absorption capacity), self-cleaning, thermal insulating (0.023 W (mK)⁻¹), and infrared shielding properties. This new DITA strategy provides a facile design of superelastic aerogels from bio-based nanomaterials, and the derived high performance multifunctional elastic aerogel is expected to be useful for a wide-range of applications.     

Hyperelastic,Robust, Fire-Safe Multifunctional MXene Aerogels with Unprecedented Electromagnetic Interference Shielding Efficiency

MXene aerogels have shown great potential for many important functional applications, in particular electromagnetic interference (EMI) shielding. However, it has been a grand challenge to create mechanically hyperelastic, air-stable, and durable MXene aerogels for enabling effective EMI protection at low concentrations due to the difficulties in achieving tailorable porous structures, excellent mechanical elasticity, and desired antioxidation capabilities of MXene in air. Here, a facile strategy for fabricating MXene composite aerogels by co-assembling MXene and cellulose nanofibers during freeze-drying followed by surface encapsulation with fire-retardant thermoplastic polyurethane (TPU) is reported. Because of the maximum utilization of pore structures of MXene, and conductive loss enhanced by multiple internal reflections, as-prepared aerogel with 3.14 wt% of MXene exhibits an exceptionally high EMI shielding effectiveness of 93.5 dB, and an ultra-high MXene utilization efficiency of 2977.71 dB g g⁻¹, tripling the values in previous works. Owing to the presence of multiple hydrogen bonding and the TPU elastomer, the aerogel exhibits a hyperelastic feature with additional strength, excellent stability, superior durability, and high fire safety. This study provides a facile strategy for creating multifunctional aerogels with great potential for applications in EMI protection, wearable devices, thermal management, pressure sensing, and intelligent fire monitoring.     

The Fabrication and Characterization of Carbon Aerogels by Gelation and Supercritical Drying in Isopropanol

We report a new method for the fabrication of carbon aerogels. Resorcinol and furfural were polymerized in isopropanol using HCl as a catalyst and the resulting alcogels were then dried directly using supercritical isopropanol, followed by carbonization under a nitrogen atmosphere. The carbon aerogels can be prepared over a range of densities (0.148–0.746 g/cm³), depending on the gelation temperature and the mass content of the reactants. The textural and transport properties of the aerogels materials were characterized by nitrogen adsorption/desorption analysis, high‐resolution transmission electron microscopy (HRTEM), magnetic susceptibility, and resistivity measurements. TEM observations show that the carbon aerogels are composed of interconnected nanoparticles with diameters ranging from 20 to 30 nm. All of the aerogel samples exhibit high Brunauer– Emmett–Teller (BET) surface areas in the range of 557–656 m²/g. The carbon aerogels produced by this new method have similar transport properties to those of carbon aerogels prepared by the traditional method.