Synthesis of Carbon and Gold Nanoparticles in Ionic Liquid Crystals: Structural Properties and Electrical Behavior for Electro‐Optical Sensors

The structural and electrical properties of ionic metal-alkanoate nanocomposites obtained based on a cadmium octanoate matrix with individual carbon and gold nanoparticles (NPs) as well as their combination are studied. Carbon and gold NPs were chemically synthesized within the smectic A phase of Cd+2(C7H15COO−)2, which served as a well-ordered nanoreactor. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) data provide information on NPs location and allow the estimation of the sizes of the synthesized NPs inside glassy liquid crystalline matrix. It is shown that the size and shape of the NPs were precisely controlled during synthesis, resulting in highly stable and organized nanocomposites. The electrical characteristics were studied in a wide temperature range corresponding to different phase states of the nanocomposites. We compared the electrical properties of both pure matrix and nanocomposites with carbon and gold NPs to identify the potential of the nanocomposite materials for designing new sensor structures. Notably, the nanocomposites exhibited anisotropic conductivity, highlighting the structural anisotropy of the material. In addition, using NPs allows fine-tuning of the electrical properties of a metal-alkanoate host matrix. The obtained nanocomposites open prospects for the development of electro-optical sensors with high sensitivity and specificity they can be used to detect a variety of chemical and physical parameters including temperature, composition of substances and environment.