Modified Carbon Electrodes: A New Approach for Bioelectrochemical Systems

Abstract

The development of sustainable and green technologies for the treatment and recovery of resources from wastes is driving a paradigm shift in waste management. Bioenergy production from waste streams can lead to the reduction of pollution, but also decrease the cost of their treatment. Among the new environmental friendly technologies, microbial bioelectrochemical systems (BESs), like microbial fuel cell (MFC) [1] or microbial electrolysis cell (MEC) [2], are considered one of the best alternatives for the sustainable waste treatment of contaminated groundwater [3], wastewater [4] and air polluted streams, and the concomitant production of energy or added value chemicals. [5] One of the critical challenges of these systems is to improve the interaction electrode-microorganism to ensure an effective transfer of electrons between the solid-state electrode and the biocatalyst. Carbon and graphene materials with various structures, shapes and properties are widely used as electrodes for BES applications due to their high conductivity, good chemical stability and relatively low cost [6,7] However, the performance of BES is often hindered by low currents and mass transport limitations. A major challenge in this context is an increase in the performance by decreasing the high overpotentials of such systems. Puig et al. [8] identified these overportentials as the main energy loss factors (8390 % of total losses) in an autotrophic denitrification in MFCs for waters with low ionic strengths. In this respect, current research is focused on studying the effects of surface chemistry and the porosity of carbons on their performance in one electrode reaction in BES [9]. The new capabilities of the design, preparations and techniques in material sciences raise the question if BES can benefit from these developments and their performance can be increased further more.