Electrochemical Synthesis of Composites Based on Silicon and Carbon Nanotube Compounds as a Platform for Biocatalyst Development

Progress in the field of modern heterogeneous catalysts requires the development of composite materials with a well-developed surface area and sorption capacity, as well as the possibility of functionalization in a specific direction. This paper presents the results of electrochemical synthesis of composites based on an organosilica matrix and multi-walled carbon nanotubes for subsequent application as a platform for enzyme immobilization. By potentiostatic electrodeposition, composite coatings based on two types of organosilica sol (STPEG and STEG) were applied to the surface of a glassy carbon electrode with the addition of MWCNTs subjected to various methods of oxidative treatment. Optimization of the deposition time in the range of 0.5–5 min revealed that the maximum electrochemical activity and heterogeneous transfer rate constants were achieved at 1 min of electrodeposition. It has been found that the use of MWCNTs oxidized in H2O2 vapors provides the best balance between hydrophilicity, conductivity, and the formation of a permeable matrix due to fewer defects and carboxyl groups. It has been demonstrated that the selected OP-SG/1 composite effectively supports mediator bioelectrocatalysis with recombinant laccase ScaSL in the presence of an ABTS mediator, as evidenced by the formation of sigmoidal CVs of catalytic oxygen reduction. The obtained results confirm that the electrodeposited organosilica composite is a promising and biocompatible material for the development of surface biocatalysts, which can be used in wastewater treatment technologies and bioreactor design.