Conducting polymers revisited: applications in energy, electrochromism and molecular recognition

Although the very first papers on conducting polymers were published almost 30 years ago, the importance and interest in this class of material have since been continuously renewed by the development of new designs with modified electrodes and their applications. In this review, we discuss the main topics of conducting polymers, especially new trends in material preparation by using template-assisted polymerization-generating materials that have a unique and highly reproducible morphology and using ionic liquids, which appears to be an interesting methodology that has yet to be further explored. There are many different applications of conducting polymers that are found in the literature, and herein, we describe their main aspects in terms of energy, electrochromism, and sensing. Due to the large interest in the energy field, this theme is discussed in terms of storage by means of the description of supercapacitors and conversion, by showing some recent advances in solar cell-modified electrodes. The changes in the optical properties of the conducting polymers in electrochromism are also presented in the discussion on the nanostructure electrode preparation, which aims at a solid-state architecture that can accomplish fast ionic diffusion. Finally, the construction of sensors and biosensors is discussed; due to their intrinsic electrocatalytic properties, conducting polymers are constantly employed for the detection of many different analytes. Additionally, by chemically modifying some functional groups, it is possible to attach different biomolecules, thereby providing a wide range of biosensors and biodetectors.