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Carbon Nanoparticle Hybrid Aerogels: 3D Double-Interconnected Network Porous Microstructure, Thermoelectric, and SolventRemoval Functions Dongxing Tan,#,†,‡ Jian Zhao,*,#,‡,‡ Caiyan Gao,† Hanfu Wang,*,§ Guangming Chen,*,† and Donglu Shi∥ †
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042, PR China § CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology of China, Beijing 100190, China ∥ The Materials Science and Engineering Program, Dept. of Mechanical and Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, Ohio 45221, United States ‡
S Supporting Information *
ABSTRACT: We report reduced graphene oxide (rGO)/single-walled carbon nanotube (SWCNT) hybrid aerogels with enhanced thermoelectric (TE) performance and removal of organic solvents by designing 3D doubleinterconnected network porous microstructures. A convenient, cost-effective, and scalable preparation procedure is proposed compared with conventional hightemperature pyrolysis and supercritical drying techniques. The obtained hybrid aerogels are systematically characterized by apparent density, scanning electron microscopy, X-ray photoemission spectroscopy, Raman spectroscopy, and porosity. An enhanced TE performance of ZT ≈ ∼8.03 × 10−3 has been achieved due to the 3D double-interconnected network porous microstructure, the energyfiltering effect, and the phonon scattering at the abundant interfaces and joints. In addition, upon a large axial compression deformation, a high degree of retention of the Seebeck coefficient and a simultaneously significant enhancement of the electrical conductivity are observed. Finally, the hybrid aerogels display high capability for the removal of diverse organic solvents and good recyclability. These findings open a new avenue for exploiting aerogels with multifunctions and widening the applications of TE materials by judicious microstructure design. KEYWORDS: reduced graphene oxide, carbon nanotube, aerogel, thermoelectric, solvent removal
1. INTRODUCTION Due to their extraordinary mechanical properties and electrically and thermally conductive functions,1−3 carbon-based nanomaterials such as graphene and carbon nanotubes (CNTs) have attracted significant interest in diverse fields of energy4−7 and the environment8,9 in recent years. Aerogels made of graphene or CNTs possess abundant micropores or nanopores.10,11 The three-dimensional (3D) porous microstructure and the intrinsic properties of carbon nanoparticles endow them with large specific surface area, low density, high strength, fast mass- and electron-transport kinetics, etc.12 So far, several preparation methods have been developed (for instance, cross-linking,13,14 hydrothermal,15 chemical vapor deposition (CVD),16 and chemical reduction methods).17 These fascinating graphene or CNT aerogels have found wide applications including energy storage or conversion,18 high-performance nanocomposite,19 and the removal of organic solvent.8,9 Hybrid aerogels containing both graphene nanosheets and CNTs may © XXXX American Chemical Society
possess unique cross-linked networks and exhibit exciting properties or functions. Unfortunately, the studies of flexible carbon nanoparticle hybrid aerogels for multifunctions still remain a challenge to date. Thermoelectric (TE) materials can realize direct interconversions between heat and electricity based on the internal mobility of solid carriers. During the past 85 wt %) was bought from Shenzhen Nanotech Port Co. Ltd.. L-Ascorbic acid and potassium permanganate were provided by Sinopharm Chemical Reagent Beijing Co., Ltd. Sulfuric acid was purchased from Beijing Chemical Works. Deionized water was used as received without any further purification or treatment. 4.2. Preparation of GO. A modified Hummers method was used to prepare GO flakes by the oxidation of natural flake graphite.54 Typically, 2 g of graphite powder, 6 g of KMnO4, and 120 mL of concentrated H2SO4 solution was mixed and cooled in an ice bath for 0.5 h. Then, the mixture was stirred at 20 °C for 2 h and subsequently mixed at 50 °C for 6 h. After the mixture was slowly poured into 120 mL of distilled water, 20 mL of H2O2 solution (30%) was added dropwise. The resultant yellow dispersion was filtrated and washed with HCl aqueous solution (10%) and water to remove the metal ions and the acidic residues. Finally, the filtrated product of GO was vacuumdried at 60 °C for 48 h. F
DOI: 10.1021/acsami.7b04938 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
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