Das Dipesh, Sabaraya Indu V, Sabo-Attwood Tara, Saleh Navid B
Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
Department of Environment and Global Health, University of Florida, Gainesville, FL 32610, USA.
Nanomaterials (Basel). 2018 Jun 5;8(6):403. doi: 10.3390/nano8060403.
Carbon nanotubes are hybridized with metal crystals to impart multifunctionality into the nanohybrids (NHs). Simple but effective synthesis techniques are desired to form both zero-valent and oxides of different metal species on carbon nanotube surfaces. Sol-gel technique brings in significant advantages and is a viable technique for such synthesis. This study probes the efficacy of sol-gel process and aims to identify underlying mechanisms of crystal formation. Standard electron potential (SEP) is used as a guiding parameter to choose the metal species; i.e., highly negative SEP (e.g., Zn) with oxide crystal tendency, highly positive SEP (e.g., Ag) with zero-valent crystal-tendency, and intermediate range SEP (e.g., Cu) to probe the oxidation tendency in crystal formation are chosen. Transmission electron microscopy and X-ray diffraction are used to evaluate the synthesized NHs. Results indicate that SEP can be a reliable guide for the resulting crystalline phase of a certain metal species, particularly when the magnitude of this parameter is relatively high. However, for intermediate range SEP-metals, mix phase crystals can be expected. For example, Cu will form Cu₂O and zero-valent Cu crystals, unless the synthesis is performed in a reducing environment.
碳纳米管与金属晶体杂化，以使纳米杂化物（NHs）具有多功能性。需要简单而有效的合成技术，以在碳纳米管表面形成不同金属物种的零价态和氧化物。溶胶-凝胶技术具有显著优势，是进行此类合成的可行技术。本研究探究了溶胶-凝胶过程的功效，并旨在确定晶体形成的潜在机制。标准电极电位（SEP）用作选择金属物种的指导参数；即，选择具有氧化物晶体倾向的高负SEP（例如Zn）、具有零价晶体倾向的高正SEP（例如Ag）以及用于探究晶体形成中氧化倾向的中等范围SEP（例如Cu）。使用透射电子显微镜和X射线衍射来评估合成的NHs。结果表明，SEP可以作为特定金属物种所得晶相的可靠指导，特别是当该参数的幅度相对较高时。然而，对于中等范围SEP的金属，可以预期会形成混合相晶体。例如，Cu将形成Cu₂O和零价Cu晶体，除非在还原环境中进行合成。
