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Abstract
Introduction
Protocol
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Chemistry

合成纳米碳和二氧化硅矩阵的表面性能

Published: March 27, 2019
doi:
10.3791/58395
, , ,
1Faculty of Physics,Adam Mickiewicz University, 2NanoBioMedical Centre, 3Department of Physicochemistry of Solid Surface, Faculty of Chemistry,Maria Curie-Skłodowska University

Summary

在这里, 我们报告了有序纳米多孔碳 (具有4.6 纳米孔尺寸) 和 SBA-15 (具有5.3 纳米孔径) 的合成和表征。本文介绍了纳米多孔分子筛的表面和结构特性、润湿性以及材料中的d2o的熔融行为。

Abstract

在这项工作中, 我们报告了合成和表征有序的纳米多孔碳材料 (也称为有序介孔碳材料 [OMC]) 与4.6 纳米的孔径, 并有序的二氧化硅多孔基质, SBA-15, 具有5.3 纳米的孔径。本文描述了纳米多孔分子筛的表面性质、润湿性以及d2o在具有相似孔径的不同有序多孔材料中的熔融行为。为此, 分别应用碳前体和溶胶-凝胶法,通过对二氧化硅基体进行浸渍, 合成了具有高阶纳米多孔结构的 omc 和 SBA-15。研究系统的多孔结构的特点是在 77 K的 n 2吸附-解吸分析。为确定合成材料表面的电化学特性, 进行了电位滴定测量;对 OMC 的结果表明, 相对于 SBA-15, phpzc 向较高的 ph 值有显著的转移。这表明, 所研究的 OMC 具有与含氧功能基团有关的表面特性。为了描述材料的表面特性, 还确定了液体穿透所研究的多孔层的接触角。毛细管上升法证实了硅墙相对于碳壁的润湿性增加, 孔隙粗糙度对流体壁相互作用的影响, 这对二氧化硅比碳硅粉要明显得多。应用介电法研究了在 OMC 和 SBA-15 中限制的d2o的熔融行为。结果表明, 与5纳米大小的 SBA-15孔隙熔融温度的抑制相比, omc 孔隙中 d2o 熔融温度的抑制度高出约 15 k。这是由所研究矩阵的吸附吸附剂相互作用的影响造成的。

Introduction

1992年, 首次采用有机模板获得了有序的纳米多孔二氧化硅材料;此后, 大量与这些结构的不同方面、合成方法、其性质的调查、修改和不同应用有关的出版物出现在文献1、2 中 ,3。对 SBA-15 纳米多孔二氧化硅基体 4的兴趣在于其独特的质量: 表面积大、毛孔宽、孔径分布均匀、化学和机械性能好。具有圆柱形孔隙的纳米多孔二氧化硅材料, 如 sba-155,通常被用作催化剂的多孔基质, 因为它们是有机反应6,7中的高效催化剂。该材料可以用多种方法合成, 这些方法可以影响其特性8、9、10.因此, 优化这些方法对于许多领域的潜在应用至关重要: 电化学设备、纳米技术、生物和医学、药物输送系统, 或粘附和摩擦学。在本研究中, 提出了两种不同类型的纳米多孔结构, 即二氧化硅和碳多孔基体。为了比较其性能, 采用溶胶-凝胶法合成了 SBA-15 基体, 并利用得到的二氧化硅基体与碳前体的浸渍法制备了有序的纳米多孔碳材料。

多孔碳材料在许多电器中都很重要, 因为它们的表面积很大, 具有独特和明确的物理化学特性, 6、11、12.典型的制备结果是材料具有随机分布的孔隙率和无序结构;一般孔隙参数变化的可能性也有限, 因此, 得到了孔隙尺寸分布相对较大的结构。对于具有高表面积和有序的纳米孔系统的纳米多孔碳材料, 这种可能性得到了扩大。在许多应用中, 更多的预测几何形状和对孔隙空间内物理化学过程的更多控制都很重要: 作为催化剂、分离介质系统、先进的电子材料和许多科学领域的纳米反应器14,15岁

为了获得多孔碳副本, 有序硅酸盐可以作为一个固体基质, 直接引入碳前体。该方法可分为几个阶段: 有序二氧化硅材料的选择;碳前驱体沉积在二氧化硅基体中;碳化;然后, 去除二氧化硅基体。这种方法可以获得许多不同类型的碳质材料, 但并非所有的无孔材料都有有序的结构。这一过程的一个重要因素是选择合适的基质, 其纳米孔必须形成稳定的三维结构16。

本文研究了孔壁类型对合成纳米多孔基体表面性能的影响。OMC 材料的表面性能反映在 OMC 二氧化硅模拟 (SBA-15) 的表面性能上。这两类材料 (OMC 和 SBA-15) 的结构和结构特性的特点是低温 N2吸附吸附-解吸测量 (在 77 k)、透射电子显微镜 (tem) 和能量色散 x 射线分析 (编辑)。

低温气体吸附-解吸测量是多孔材料表征中最重要的技术之一。氮气由于其纯度高, 并且有可能与固体吸附剂产生强烈的相互作用, 因此被用作吸附剂。这种技术的重要优点是方便用户使用的商业设备和相对容易的数据处理程序。氮吸附剂/解吸等温线的测定是基于吸附剂分子在广泛的压力范围内在 77 K 的位置上的积累.采用巴雷特、乔伊纳和哈伦达 (BJH) 的方法, 从实验吸附或解吸等温线计算孔径分布。BJH 方法最重要的假设包括平面和吸附物在被调查表面上的均匀分布。然而, 这一理论是基于开尔文方程, 它仍然是最广泛使用的方法, 计算孔径分布在介孔范围内。

为了评价样品的电化学特性, 采用了电位滴定法。材料的表面化学取决于与表面异质原子或官能团的存在有关的表面电荷。通过接触角分析, 研究了表面性能。毛孔内的润湿性提供了有关吸附吸附剂相互作用的信息。利用介电松弛光谱 (DRS) 技术研究了壁面粗糙度对两种样品中封闭水熔融温度的影响。介电常数的测量允许对熔融现象的研究, 因为液体和固相的极化性是不同的。电容温度依赖性斜率的变化表明, 系统中发生了熔融现象。

Protocol

1. OMC 材料的制备 作为 OMC 前体的二氧化硅基体的合成 加入50毫升 HCl (36%-38%), 制备 1.6 m HCl 的360毫升在500毫升的圆底瓶中, 然后加入310毫升的超纯水 (电阻率为 18.2 mmy·cm)。 除此之外, 还加入10克 PE 10500 聚合物 (6.500 g/mol)。 将烧瓶放在超声波浴缸中。将溶液加热至 35°c, 搅拌至固体聚合物完全溶解, 形成均匀的混合物。 在烧瓶中加入10克的 1, 3, 5-三…

Representative Results

为了表征 OMC 和 SBA-15 样品的多孔结构, 记录了 N2吸附-解吸等温线在 77 k。实验图1a-d给出了实验 n2 气体吸附-解吸等温线, 描述了所研究系统的特征, 以及从吸附和解吸数据中得到的孔径分布 (psd)。拐点在吸附等温线上的位置 (图 1a, c) 表示中间孔充填过程开始的压力。根据 Kelvin 方程, 计?…

Discussion

在制备有序介孔碳材料过程中的关键步骤包括制备有序介孔二氧化硅材料, 作为模板, 其结构性能明确, 影响最终材料的性能,在氮气气氛下的回火碳化步骤。对具有圆柱形孔28的介孔有序硅酸盐的典型制备方法进行了改进,涉及到 pe10500 聚合物在结构改进中的应用。材料的性能。模板的三维、互联和稳定的多孔结构是制备介孔碳材料所必需的。此外, 制备的一个关键缺点是模板去除?…

Disclosures

The authors have nothing to disclose.

Acknowledgements

作者要感谢国家科学中心提供财政支持, 并提供了赠款。DEC-2019/BB越来越/379/11 和 UMO2-2016/STM/00092。提交人还感谢波兰人力资本计划人力资本PO kl 4.1.1 以及国家研究和发展中心在研究赠款下提供的部分支持。PBSNAJN13 2012。提交人特别感谢波兰卢布林 Maria Curie-skvodowska 大学化学系国际现象司 l. Hovysz 教授的善良和能够测量 SBA-15 纳米粒子的润湿性。

Materials

1,3,5-trimethylbenzene Sigma-Aldrich, Poland M7200 Sigma-Aldrich Mesitylene, also known as 1,3,5-trimethylbenzene, reagent grade, assay: 98%.
anhydrous ethanol POCH, Avantor Performance Materials Poland S.A. 396480111 Assay, min. 99.8 %, analysis-pur (a.p.)
ASAP 2020. Accelerated Surface Area and Porosimetry System Micromeritics Instrument Corporation, Norcross, GA, USA Samples were outgassed before analysis at 120 oC for 24 hours in degas port of analyzer. The dead space volume was measured for calibration on experimental measurement using helium as a adsorbate.
Automatic burette Dosimat 665 Metrohm, Switzerland The surface charge properties were experimentally determined by potentiometric titration of the suspension at constant temperature 20°C maintained by the thermostatic device. Prior to potentiometric titration measurements, the solid samples were dried by 24 hours at 120 oC. The initial pH was established by addition of 0.3 cm3 of 0.2 mol/L HCl. T The 0.1 mol/L NaOH solution was used as a titrant, added gradually by using automatic burette.
Digital pH-meter pHm-240 Radiometer, Copenhagen Device coupled with automatic burette
ethyl alcohol POCH, Avantor Performance Materials Poland S.A. 396420420 Assay, min. 96 %.analysis-pur (a.p.)
glucose POCH, Avantor Performance Materials Poland S.A. 459560448 assay 99.5%
Hydrochloric acid POCH, Avantor Performance Materials Poland S.A. 575283115 Hydrochloric acid, 35 – 38% analysis-pur (a.p.)
HOPG graphite substrate Spi Supplies LOT#1170906 HOPG SPI-2 Grade, 20x20x1 mm
Impedance analyzer Solartron 1260 Solartron
Pluronic PE 6400 polymer BASF (Polska) (EO13PO70EO13)
Pluronic PE10500 BASF Canada Inc. Molar mass 6500 g/mol
potassium hydroxide Sigma-Aldrich, Poland P5958 Sigma-Aldrich BioXtra, ≥85% KOH basis
SEM microscope JEOL JSM-7001F Scanning Electron Microscope with EDS detector
Sigma Force Tensiometer 701 KSV, Sigma701, Biolin Scientific force tensiometer
Sulfuric acid (VI) POCH, Avantor Performance Materials Poland S.A. 575000115
surface glass type KS 324 Kavalier Megan Poland 80 % of SiO2 , 11% of Na2O and 9% of CaO
Tecnai G2 T20 X-TWIN FEI, USA Transmission Electron Microscope with EDX detector.
TEM microscope JEOL JEM-1400
temperature controller ITC503 Oxford Instruments
Tetraethylorthosilicate Sigma-Aldrich, Poland 131903 Tetraethyl silicate, TEOS, reagent grade, assay 98%
Ultrapure water Millipore, Merck KGaA, Darmstadt, Germany SIMSV0001 Simplicity Water Purification SystemUltrapure Water: 18.2 MegOhm·cm, TOC: <5 ppb
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Nanoporous CarbonNanoporous SilicaPorous Surface CharacteristicsConfinement EffectEnergyMedicineEnvironmentSynthesisCharacterizationWetting ParametersNanotechnologyBiologyMedicinePolyethylene 10500135-trimethylbenzeneTetraethyl OrthosilicateThermal TreatmentImpregnation SolutionsWaterSulfuric AcidGlucose

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Sterczyńska, A., Śliwińska-Bartkowiak, M., Zienkiewicz-Strzałka, M., Deryło-Marczewska, A. Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices. J. Vis. Exp. (145), e58395, doi:10.3791/58395 (2019).
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