Hollow microtubes made of carbon, boron and gold: novel semiconducting nanocomposite material for applications in electrochemistry and temperature sensing

Carbon based nanocomposites have recently been intensively investigated as a new class of functional hybrid materials. Here, we present a procedure to obtain a new nanocomposite material made of carbon, boron and gold for applications in electrochemistry and electronics. The presented fabrication protocol uses cellulose fibers as a template that is first modified with an inorganic nanocomposite material consisting of gold nanoparticles (AuNPs) embedded in a polyoxoborate matrix, and then is subjected to the process of thermal decomposition. The as obtained material has a form of tubes with a diameter of a couple of micrometers that are composed of carbonized cellulose coated with the polyoxoborate–AuNP nanocomposite. This inorganic shell, which covers the outer surface of the carbon microtubes, serves as a scaffold that makes the structure stable. The obtained material exhibits electrical properties of a semiconductor with the width of the band gap of about 0.6 eV, and forms Schottky contact with a metal electrode. We show that the new material is suitable for preparation of the NCT-type thermistor. We also demonstrate application of the new nanocomposite in electrochemistry for modification of the surface of a working electrode. Experiments carried out with three exemplary redox probes show that the electrochemical performance of the modified electrode depends greatly on the amount of AuNPs in the nanocomposite.