生物质基柔性超级电容器研究进展

随着可穿戴设备的发展及公众环保意识的提升,开发高性能兼绿色经济型的柔性电化学储能器件已成为研究热点。以生物质为前驱体制备性能优异的储能材料,可以显著降低生产成本,实现碳资源的可持续利用,具有极大的发展潜力和实际应用价值。该文介绍了柔性超级电容器的电极材料、柔性隔膜和各种组装方式,分析了木基、纤维素凝胶基、纸基以及生物质废料电极材料的特点和优势,阐述了生物质基柔性隔膜研究现状,包括纤维素纸隔膜和生物隔膜;此外,介绍了叠层型（三明治型）、叉指型（微型叉指化）、纤维型（线型）柔性超级电容器,并对比了不同组装方式的柔性超级电容器在性能上的差异;最后分析了生物质材料用于柔性超级电容器面临的挑战,对柔性器件未来发展方向进行了展望。     

绿色节能背景下碳气凝胶的发展及应用

介绍了碳气凝胶的制备工艺,全面综述了碳气凝胶在吸附、保温、催化、超级电容器、储能等领域中的主要研究进展。碳气凝胶是一种新型非晶态有机纳米材料,单位比表面积高(400～3 000 m2/g)、孔隙率高(80%～99%)、具有超低的热导率,在吸附、相变保温材料中有重要应用。碳气凝胶强度大、稳定性好、具有丰富的反应位点,这些因素决定了它是优秀的催化剂载体;同时碳气凝胶还展现出有机气凝胶所没有的优秀导电性。     

碳气凝胶及其在污水处理中的应用

碳气凝胶是由碳纳米材料形成的三维多孔网络结构材料,具有比表面积大、孔隙率高、化学性质稳定和结构可调等优点,被广泛用于水污染处理中,用于去除油、有机溶剂、染料、重金属离子等。综述了碳气凝胶及其复合材料的研究进展,讨论了有机碳气凝胶、生物质基碳气凝胶、石墨烯基碳气凝胶三类碳气凝胶材料的组成、制备和吸附性能,总结了碳气凝胶在水处理中的应用并简要分析了碳气凝胶材料当前面临的挑战以及未来的发展前景。     

植物纤维素基碳气凝胶的制备及应用研究进展

植物纤维素基碳气凝胶具有低密度、可生物降解、优异的吸附性能和电化学性能稳定等特点。本文围绕其原料来源、制备工艺及其在环境治理和能量储存与转化方面的应用,分析了植物纤维素基碳气凝胶的性能及研究进展。详细叙述了以棉花、木材、竹纤维等为原料的植物纤维素基碳气凝胶的制备方法,如：溶胶-凝胶法、水热炭化法、直接炭化法等。分析了制备过程中干燥方法、溶剂的选择及置换、复合改性等影响因素,并介绍了碳气凝胶在空气净化、油水分离、有毒化合物、重金属离子的去除等环境治理及能量转化与储存方面的。     

纤维素基碳气凝胶研究进展

介绍了纤维素碳气凝胶原材料的主要来源及各原材料的特点,重点举例阐述可直接利用型纤维素制备纤维素基碳气凝胶材料的不同工艺方法,综合分析了纤维素基碳气凝胶作为多功能材料的一些前沿的应用研究。总结了该领域存在的挑战并展望了纤维素基碳气凝胶的发展前景。     

甘蔗渣纤维素基碳气凝胶的制备及吸附性能研究

通过对甘蔗渣进行碱/酸处理提取甘蔗渣纤维素,采用氢氧化钠/脲溶液将纤维素溶解,并通过在水中再生、冷冻干燥及在不同温度下碳化,制备具有优异疏水吸油性能的甘蔗渣纤维素基碳气凝胶。采用扫描电镜（SEM）、红外光谱（FT-IR）、X射线衍射（XRD）、BET法比表面积、水接触角（WCA）等测试方法对制备的甘蔗渣纤维素基碳气凝胶进行分析表征,并进行不同油类和有机溶剂的吸附、解吸实验。结果表明,制备的甘蔗渣纤维素基碳气凝胶拥有不规则的片-孔式网络状三维结构,具有轻质、高疏水、高比表面积等特性。高温碳化不仅可以改善碳气凝胶的轻质抗压性能、比表面积和孔径,还可以增强其疏水性及吸附性能。当碳化温度为800 ℃时,制备的CA-2-800表现出较好的轻质性（密度为33.4 mg/cm³）、高疏水性（水接触角为136°）和高比表面积（468.24 m²/g）。CA-2-800对柴油、汽油、泵油、正己烷、甲苯、三氯甲烷具有较好的吸附能力（20.2~66.3 g/g）。吸附动力学研究表明,CA-2-800在30 s内对汽油、柴油均能达到吸附平衡,且对三氯甲烷进行10次吸附-解吸循环吸附实验仍保留97%的吸附性能。     

生物质基水凝胶的传感应用进展

生物质材料是由动物、植物以及微生物等生命体衍生得到的材料,具备来源广泛、绿色安全、可再生和可生物降解等重要特征。生物质基水凝胶是以天然生物质大分子为原材料制备的水凝胶,已被广泛应用于污染物吸附、药物载体、生物工程以及多功能传感等领域。本文简要介绍了几种常见生物质基水凝胶的特点,包括基于蛋白质、纤维素、海藻酸盐、淀粉和壳聚糖等制备的水凝胶。同时,归纳了生物质基水凝胶在生物、应变、气体、湿度和温度等方面的最新传感应用。最后,结合目前研究现状,指出了生物质基水凝胶未来推广应用面临的挑战并提出了针对性解决思路。     

酚醛基炭气凝胶的研究进展

炭气凝胶是一种多孔纳米炭材料,具有低密度、高孔隙率、高比表面积、优异的导电性和良好的成型性能等优点,是炭材料研究的热点和重要方向。本文旨在通过阐明酚醛基炭气凝胶的制备原料和制备工艺的发展过程,从而突出未来酚醛基炭气凝胶的发展方向。基于此,本文首先重点介绍了酚醛基炭气凝胶的制备方法,主要包括溶胶-凝胶化、干燥以及炭化过程三个最主要的步骤;进而详述了以三种不同的前体,即间苯二酚、苯酚、生物质单宁/木质素分别制备酚醛基炭气凝胶的方法及其优缺点;接下来对酚醛基炭气凝胶作为吸附材料（气体吸附/液体吸附）的吸附量以及在电化学储能以及其他领域的应用进行了综述;最后对酚醛基炭气凝胶未来的研究方向和发展前景进行了总结和展望。文章指出,传统的以间苯二酚为原料辅以超临界干燥的方法制备的酚醛基炭气凝胶,原料成本较高,反应条件苛刻,实际生产应用受限;以苯酚取代间苯二酚,亦或是采用冷冻干燥等方法改进其制备工艺,可以大幅度降低原料和生产成本;但未来的发展方向和重点将是绿色、可再生的生物质原料（单宁、木质素、腰果酚等）及复合气凝胶材料的研发。因此,酚醛基炭气凝胶在未来的发展还需要进一步改进其制备工艺和方法,拓宽其原料来源,从而提高性能,扩大应用领域。     

生物质基介孔碳材料制备的研究进展

分别介绍了近年来采用硬模板法、软模板法、溶胶-凝胶法和水热法等主要方法制备生物质基介孔碳材料及其在吸附、催化、药物控释和超级电容器等领域应用的研究进展。最后对生物质基介孔碳材料今后开展进一步研究的方向进行了展望。     

利用玉米秸秆纤维素制备碳气凝胶的研究

将玉米秸秆中的纤维素通过碱处理以及漂白处理的方法提取出来，再将玉米秸秆纤维素分散在水中，并通过超声以及冷冻干燥的方法制成玉米秸秆纤维素气凝胶，最后将气凝胶高温碳化制得玉米秸秆纤维素碳气凝胶。通过扫描电镜（SEM），红外光谱（FT-IR）,X射线衍射仪，水接触角（WCA）等对玉米纤维素气凝胶以及碳气凝胶进行表征测试，并使用不同油类以及有机溶剂进行玉米秸秆纤维素碳气凝胶的吸附、解吸实验。结果表明，制备的玉米秸秆纤维素碳气凝胶（CA-200）相较于同质量比的气凝胶（AE-200）具有更好的三维结构以及优良的疏水性能。制得的碳气凝胶其水接触角能达到135°，并且其对植物油、润滑油以及乙醇的吸附性能可达自身质量的80～140倍。相较于没有经过碳化的气凝胶AE-200的吸附性能提升了50倍左右。     

生物质基多孔材料在保温材料中的研究进展

环保、节能、高效是保温材料未来的主要研究方向, 开发以生物质为原料的保温材料是未来趋势。生物质基多孔材料是指以可再生的生物质为前驱体制备的多孔材料, 其原料来源广, 制备方法多样, 具有孔隙率高、密度小、质量轻等优异特点, 在保温领域有很大的应用潜力。本文概述了多孔材料的保温机理, 并综述了近几年国内外对纤维素基、淀粉基、壳聚糖基、植物蛋白基多孔材料的研究, 重点介绍了表面活性剂发泡法、冷冻干燥法、致孔剂法、模具热压法、溶剂交换相分离法等在生物质基多孔材料制备中的应用。分析了生物质多孔材料存在的问题, 并对多孔保温材料未来的研究方向进行了展望。     

生物质炭基材料在有机催化转化中的应用

近年来,生物质因具有富碳可再生、储量丰富、环境友好、价格低廉等特点被作为原料广泛应用于制备生物质炭基材料。本文综述了以生物质为原料衍生炭基材料作为催化剂在有机转化反应中的相关研究进展,重点介绍了杂原子掺杂、金属杂化策略所制备炭基催化材料在液相催化加氢、氧化、偶联等有机转化反应中的催化性能,进而阐明了炭基催化剂与催化活性之间的构效关系。最后,本文总结了生物质炭基催化剂在有机催化反应中的优势,指出了目前生物质衍生炭基催化剂材料合成和有机转化研究领域面临的挑战,并对此领域的未来发展趋势进行了分析与展望。     

Controllable synthesis of cellulose/methylene bisacrylamide aerogels for enhanced adsorption performance

Cellulose-based aerogels have been regarded as potential adsorbent materials because of their unique structural features and chemical stability. Herein, we prepared the composite aerogels containing cellulose and N,N′-methylene bisacrylamide (MBA) using N-methylmorpholine-N-oxide (NMMO) as a green solvent via a freeze-drying process. Owing to the strong chemical interaction between CC bonds of MBA and the functional groups of cellulose, as-obtained cellulose/MBA aerogels present favorable MBA-induced thermal/mechanical stable three-dimensional network structure, in which the abundant macroporous structure, low density and high porosity lead to a significantly enhanced adsorption capacity (260.31 mg∙g⁻¹) toward congo red dye in aqueous solution compared with the pure cellulose aerogels. Moreover, the effect of the cellulose concentration and cross-linking degree on the morphology and adsorption properties for cellulose/MBA aerogels was systematically investigated. This present work provides a low-cost and environmental-friendly synthesis method for designing the functionalization of cellulose-based aerogel, which may be achieved the advanced performance in wastewater treatment.     

Carbon aerogels derived from cresol–resorcinol–formaldehyde for supercapacitors

The objective of the present paper is to demonstrate the possibility to synthesize mixed carbon aerogels (denoted C_mRF) from cresol (C_m), resorcinol (R) and formaldehyde (F), as an alternative economic route to the classical RF synthesis. These porous carbon aerogels can be used as electrode materials for supercapacitors with a high volume-specific capacitance. Organic precursor gels were synthesized via polycondensation of a mixture of resorcinol and cresol with formaldehyde in an aqueous alkaline (NaOH) solution. After gelation and aging the solvent was removed via drying at ambient pressure to produce organic aerogels. Upon pyrolysis of the organic aerogels at 1173 K, monolithic carbon aerogels can be obtained. By controlling the catalyst (Cat) molar ratio (C_m+R/Cat) in the range 200–500, up to 70% of the resorcinol can be replaced with the cheap cresol. The resulting homogeneous organic aerogels exhibit a drying shrinkage below 15% (linear). The shrinkage and mass loss upon pyrolysis of the mixed aerogels increase with increasing cresol content. Nitrogen adsorption at 77 K was employed to characterize the microstructure of the carbon aerogels. The data show that the porous structure of mixed carbon aerogels is similar to that of RF carbon aerogels. Cyclic voltammetry measurements show that the as-prepared C_mRF carbon aerogels exhibit a high volume-specific capacitance of up to 77 F/cm³.     

Mechanical modeling and simulation of aerogels: A review

Aerogels are solids with exceptional characteristics, such as ultra-low density, high surface area, high porosity, high adsorption and low-thermal conductivity. Due to these characteristics, aerogels are emerging to be a popular material among the scientific community, since their discovery in 1931. However, their applicability has remained questionable due to the poor mechanical characteristics, such as brittleness and low tensile strength. In the last three decades, due to the rapid development in the computational resources and numerical methods, a deeper understanding of physical behavior and properties of these materials have been extensively investigated. In this work, an effort is made to critically analyze and categorize the computational models and simulation results available for silica, carbon, carbon nanotubes, graphene, and cellulose aerogels. This work focused on a better understanding of how these materials were computationally modeled and simulated over the time-period and at different length-scales, wherein primary approaches, such as molecular dynamics (MD), coarse-grained, micromechanical multiscale and continuum mechanics modeling, were discussed. It also strives to give an insight into the areas where further computational studies are required, which could lead to numerous other application fields. The systematic review provides a mechanistic basis for reliable applications of aerogels.     

PREPARATION OF ORGANIC MESOPOROUS GEL BY SUPERCRITICAL/FREEZE DRYING

ABSTRACT

Resorcinol-formaldehyde (RF) aerogels were synthesized by sol-gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution and supercritical drying with carbon dioxide. The control of mesoporous structure of the aerogels was studied by changing the amounts of resorcinol, formaldehyde, distilled water, and sodium carbonate (basic catalyst) used in the polycondensation. As a result of characterization by nitrogen adsorption, the mesopore radius of the RF aerogel was controlled in the range of 2.5 – 9.2 nm. After the hydrogels were immersed in excess of t-butanol, RF cryogels were prepared by freeze drying. The cryogels prepared were mesoporous materials with high surface areas > 500 m²/g and large mesopore volumes > 0.8 cm³/g. Although the surface areas and mesopore volumes of RF cryogels were smaller than those of RF aerogels, the cryogels were useful precursors of mesoporous carbons.     

多元酸催化炭气凝胶的常压制备及表征

在多元有机酸催化和表面活性剂的作用下,间苯二酚和甲醛反应生成有机凝胶,经过常压干燥、高温炭化得到炭气凝胶。用扫描电镜(SEM)、X射线衍射(XRD)和亚甲基蓝吸附测试表征所制备的样品。结果表明,所制备的炭气凝胶属于非晶态物质,呈现均匀的球状结构,且微球内富含连通的电荷转移的孔道,其比表面积达到740m2/g。循环伏安扫描测试表明,所制备的炭气凝胶具有良好的电化学性能,有望成为超级电容器的电极材料。