Fernández de Luis Roberto, Larrea Edurne S, Orive Joseba, Lezama Luis, Costa C M, Lanceros-Méndez S, Arriortua María I
BCMaterials (Basque Centre for Materials, Applications & Nanostructures) Bld. Martina Casiano, 3rd. Floor UPV/EHU Science Park Barrio Sarriena s/n 48940 Leioa Spain
Departamento de Mineralogía y Petrología, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, Apdo. 644 E-48080 Bilbao Spain.
RSC Adv. 2019 Dec 20;9(72):42439-42449. doi: 10.1039/c9ra04227j. eCollection 2019 Dec 18.
Silver vanadium oxide (SVO) and Silver Vanadium Oxide/Vanadium Oxide (SVO@VO) composite hydrogels are formed from the self-entanglement of β-AgVO nanoribbons and slightly reduced vanadium oxide (VO) (V V O) nanoribbons; respectively. Starting from randomly distributed nanoribbons within hydrogels, and after a controlled drying process, a homogeneous xerogel system containing tuneable SVO : VO ratios from 1 : 0 to 1 : 1 can be obtained. The precise nanoribbons compositional control of these composite system can serve as a tool to tune the electrical properties of the xerogels, as it has been demonstrated in this work by impedance spectroscopy (IS) experiments. Indeed, depending on the composition and temperature conditions, composite xerogels can behave as electronic, protonic or high temperature ionic conductors. In addition, the electric and protonic conductivity of the composite xerogels can be enhanced (until a critical irreversible point), through the temperature triggered charge carrier creation. As concluded from thermogravimetry, IR, UV-Vis and EPR spectroscopy studies, besides the SVO : VO ratio, the thermal induced oxidation/reduction of V to V, and thermally triggered release of strongly bonded water molecules at the nanoribbon surface are the two key variables that control the electric and ionic conduction processes within the SVO and composite SVO/VO xerogels.
氧化银钒（SVO）和氧化银钒/氧化钒（SVO@VO）复合水凝胶分别由β-AgVO纳米带和轻度还原的氧化钒（VO）（VVO）纳米带的自缠结形成。从水凝胶中随机分布的纳米带开始，经过可控干燥过程后，可以获得一种均匀的干凝胶体系，其SVO:VO比例可在1:0至1:1之间调节。这些复合体系中纳米带精确的成分控制可作为调节干凝胶电学性质的一种手段，正如本工作中通过阻抗谱（IS）实验所证明的那样。实际上，根据组成和温度条件，复合干凝胶可表现为电子导体、质子导体或高温离子导体。此外，通过温度引发的电荷载流子产生，复合干凝胶的电导率和质子导率可以得到提高（直至达到临界不可逆点）。根据热重分析、红外光谱、紫外可见光谱和电子顺磁共振光谱研究得出的结论，除了SVO:VO比例外，V到V的热诱导氧化/还原以及纳米带表面强结合水分子的热触发释放是控制SVO和复合SVO/VO干凝胶内电传导和离子传导过程的两个关键变量。
