Application of TiO2 and Rh as cathode catalyst to boost the microbial electrosynthesis of organic compounds through CO2 sequestration

Abstract

Microbial electrosynthesis (MES) is a budding technology, where the principles of bioelectrochemical systems are employed to sequester CO2 and concomitantly produce value-added organic chemicals. The inferior production rate of organic chemicals in MES is a major roadblock in the real field application of this novel technology, which needs to be overcome by applying biocompatible metal-based cathode catalysts. Therefore in the present investigation, Rh and TiO2 microparticles were applied as cathode catalyst in MES and performance was compared based on production rate of organic chemicals and electrochemical parameters. The electrochemical properties of Rh and TiO2 were illustrated by employing cyclic voltammetry and electrochemical impedance spectroscopy, and reduction in overpotential associated with hydrogen evolution reaction was noticed for TiO2 coated electrode. Moreover, the production rate of acetate was also enhanced by 2.14 and 1.3 times due to the application of TiO2 (MES-Ti) and Rh (MES-Rh), respectively, as cathode catalyst in comparison to the MES operated without any cathode catalyst. Better bacterial attachment and more production of hydrogen were also observed for MES-Ti, which was fundamental to the improved performance of MES-Ti. Therefore, TiO2 can be deliberated as an effective cathode catalyst in MES to escalate its production rate.