Highly Hierarchical Fibrillar Biogenic Silica with Mesoporous Structure Derived from the Perennial Plant Equisetum Fluviatile

Abstract

A new discovery of highly hierarchical fibrillar biogenic silica with mesoporous structure derived from the perennial plant Equisetum f luviatile was made. By removing the organic compounds through chemical and heat treatment, the biogenic silica skeleton can largely retained the original highly hierarchical structure of the plant stems. Infrared spectra, X-ray diffraction, and small-angle X-ray scattering, as well as nitrogen sorption analysis, were employed to characterize the crystalline phases, nanostructure, and porosity of the resulting material. Scanning electron microscopy and transmission electron microscopy investigation reveal that the biogenic silica are fibers with diameters of about 120−150 μm and lengths of more than a few centimeters. These fibers consist of smaller fasciculus with diameters of about 5−15 μm that are composed of three levels of particles with mass and surface fractal characteristics: primary particles on the order of 3−5 nm, secondary particles on the order of 9−12 nm, and tertiary particles on the order of 90−120 nm in size. It is also shown that the biogenic silica have mesoporous structure with an average pore size of 4−6 nm and a specific surface of 100−300 m 2 /g. Heat treatment at high temperature and residual K + significantly affects the characteristics of the mesoporous structure of the biogenic silica, although it has little effect on the surface fractal structure of the secondary particles.

Hyaluronic acid encapsulated aminated mesoporous silica nanoparticles for pH‐responsive delivery of methotrexate and release kinetics

“…FT-IR spectra of AMSN, MTX, HA, and AMSN-MTX-HA Successful preparation of AMSN-MTX-HA can be confirmed by the FT-IR spectra of AMSN-MTX-HA and other samples (Figure 2). AMSN displays a sharp peak at around 1101 cm À1 , corresponding to the antisymmetric stretching vibration of Si O, 29 and another two small peaks at 1635 and 2927 cm À1 are assigned to the bending of N H and the asymmetric vibration of C H, respectively. 30 The peak at around 1500 cm À1 on the spectrum of MTX is related to the aryl system of MTX.…”

“…35 The XRD pattern of AMSN shows only a wide peak at around 2θ = 22.5 , agreeing well with the previous report. 29 The XRD patterns of AMSN-MTX and AMSN-MTX-HA are quite similar to that of AMSN, suggesting that the loading of MTX and the subsequent introduction of HA do not alter the crystal structure…”

Synthesis and Regeneration of Ni-Phyllosilicate Catalysts Using a Versatile Double-Accelerator Method: A Comprehensive Study

“…Silica-based materials have been widely used as the sacrificial template to produce nickel phyllosilicates. In order to control the morphology and pore structure of synthetic silica materials, it is inevitable to use surfactants and polymers as templates, which easily result in complicated operation, low output, high cost, and environmental pollution . As we know, rice husk, , Equisetum fluviatile, bamboo leaves, reed leaves, and other silicon-rich biomasses have been used as precursors to produce biomass-based silica with high purity.…”

“…In order to control the morphology and pore structure of synthetic silica materials, it is inevitable to use surfactants and polymers as templates, which easily result in complicated operation, low output, high cost, and environmental pollution . As we know, rice husk, , Equisetum fluviatile, bamboo leaves, reed leaves, and other silicon-rich biomasses have been used as precursors to produce biomass-based silica with high purity. Distillers’ grains are the typical biomass waste from distilling wine with a high dry weight silica content above 15 wt %, which can be a promising raw material to prepare biomass-based silica.…”

Three-dimensional Porous Biogenic Si/C Composite for High Performance Lithium-ion Battery Anode Derived from Equisetum Fluviatile

“…Key words: equisetum fluviatile; lithium-ion battery; porous silicon; silicon/carbon composite; anode material 锂离子电池具有高能量密度和长循环寿命等优 点，目前广泛应用于新能源汽车、移动电子设备和 智能装置等领域 [1][2] 。目前商用锂离子电池中最常见 的负极材料仍然是石墨材料，但由于其比容量相对 较低(372 mAh/g) ，难以满足发展的迫切需要 [3][4] 。 锂离子电池硅负极材料具有理论比容量高(4200 mAh/g) 、工作电压低(＜0.5 V) 、成本低廉和自然 界来源丰富等优点，被认为是锂离子电池最有潜力 的负极材料之一 [5][6] 。然而硅在脱锂-嵌锂的过程中 存在剧烈的体积变化(~300%) ，导致活性物质粉碎 和不稳定的固体电解质(SEI)膜中间相持续生成，从 而直接造成硅负极容量的迅速衰减 [7][8] 。研究者制备 出各种硅材料来解决上述问题，如：硅纳米线 [9] 、 硅纳米球 [10] 和空心硅纳米球 [11] 等，这些材料在锂离 子电池中表现出较好的电化学性能。然而，利用化 学气相沉积和激光烧蚀等传统方法制备单质硅，不 仅成本高，有污染，而且过程复杂，也限制了其大 规模生产 [12][13] 。所以，开发低成本、可规模化、制 备流程简便且绿色环保的可持续硅源迫在眉睫。 木贼是现存最古老的活体维管植物之一，它从 土壤中吸收硅酸和可溶性二氧化硅， 并在其细胞壁、 细胞内和细胞间隙中沉积二氧化硅 [14] 。溪木贼是木 贼科的典型成员， 可沿淡水岸边或浅水中茂密生长， 目前一般大量种植作为景观植物。溪木贼是纳米二 氧化硅及其衍生物的天然储集层，其二氧化硅含量 占干重的 25%，是二氧化硅含量最多的植物 [15] 。不 仅如此，溪木贼还含有良好的纳米级二氧化硅，有 望成为硅材料的理想来源。最近，有报道 [16] 用稻壳 作为锂离子电池硅负极的硅源，但由于稻壳的块状 结构，最终只得到硅纳米颗粒。而从木贼中提取的 生物质二氧化硅，具有三维分级多孔结构 [17] 。利用 溪木贼作为生物质硅源，不仅可以实现可再生生物 质的最大利用，而且可以为硅基材料的工业化生产 提供绿色、可规模化和可持续发展的低成本和充足 的资源。 Raman spectra for 3D-bio-Si and 3D-bio-Si/C 图 3 是多孔 3D-bio-Si 和多孔 3D-bio-Si/C 的拉 曼光谱图。多孔 3D-bio-Si 和多孔 3D-bio-Si/C 分别 在 516 和 507 cm -1 处出现 Si 峰， Si 峰发生红移的原 因可能是由于 Si 和 C 之间的热膨胀系数差异造成的 应力而导致的 [19] 。在 1342(D 带)和 1585 cm -1 (G 带) 处的两个峰是多孔 3D-bio-Si/C 中碳材料的特征 峰，表明碳被成功地包覆在多孔 3D-bio-Si 的表面。 在多孔 3D-bio-Si 的 300 cm -1 和多孔 3D-bio-Si/C 的 289 cm -1 处分别有一个弱峰，有可能存在痕量的 SiO2 [20] 。图 4 是多孔 3D-bio-Si 的高分辨 X 射线光 电子能谱图(XPS)，在 103 和 99 eV 附近有两个明显 的峰，分别对应于 SiO2 和 Si，表明在浅度氧化过程 中 Si 表面存在氧化薄层 [21] 图 6 是多孔 3D-bio-Si/C 的 SEM 和 TEM 照片。 碳膜包覆后的多孔 3D-bio-Si，仍然保持三维多孔结 构，碳膜均匀地包覆在硅的表面和孔的内表面。图 6(b, c)是多孔 3D-bio-Si/C 的透射电镜照片，同样可 以看到在硅的外表面有一层均匀的碳膜； 在 HRTEM 照片(图 6(c))中，约 0.31 nm 的晶格条纹对应于立方 相 Si 的(111)平面,并有明显的碳和多孔 3D-bio-Si 的 界限，说明碳膜将 Si 均匀地包裹在内部。 图 7 是多孔 3D-bio-SiO2、多孔 3D-bio-Si 和多 孔 3D-bio-Si/C 的 N2 吸附-脱附等温线和孔径分布曲 线。样品的 N2 吸附-脱附等温线均属于典型的 IV 型 曲线，表明样品为介孔材料 [23] 。SiO2 的孔径主要分 布在 6 nm 左右， 而多孔 3D-bio-Si 的孔径分布变宽、 图 6 多孔 3D-bio-Si/C 的(a)扫描电镜图片、(b)透射电镜图片和(c)高分辨透射电镜图片 图 7 多孔 3D-bio-SiO2、多孔 3D-bio-Si 和多孔 3D-bio-Si/C 的(a)N2 吸附-脱附等温线和(b)孔径分布曲线 Fig. 7 (a) Nitrogen adsorption-desorption isotherms and (b) pore size distribution curves for 3D-bio-SiO2, 3D-bio-Si and 3D-bio-Si/C Si/N-doped C Rice husk Spheres 0.5 1031 (100 th ) [10] Si/C Rice husk Spheres 0.1 560 (180 th ) [26] Si/N-doped C Bamboo charcoal Porous 0.2 603 (120 th ) [27] Si@C/R...…”