Functional group surface modifications for enhancing the formation and performance of exoelectrogenic biofilms on the anode of a bioelectrochemical system

Abstract

Various new energy technologies have been developed to reduce reliance on fossil fuels. The bioelectrochemical system (BES), an integrated microbial–electrochemical energy conversion process, is projected to be a sustainable and environmentally friendly energy technology. However, low power density is still one of the main limiting factors restricting the practical application of BESs. To enhance power output, functional group modification on anode surfaces has been primarily developed to improve the bioelectrochemical performances of BESs in terms of startup, power density, chemical oxygen demand (COD) removal and coulombic efficiency (CE). This modification could change the anode surface characteristics: roughness, hydrophobicity, biocompatibility, chemical bonding and electrochemically active surface area. This will facilitate bacterial adhesion, biofilm formation and extracellular electron transfer (EET). Additionally, some antibacterial functional groups are applied on air cathodes in order to suppress aerobic biofilms and enhance cathodic oxygen reduction reactions (ORRs). Various modification strategies such as: soaking, heat treatment and plasma modification have been reported to introduce functional groups typically as O-, N- and S-containing groups. In this review, the effects of anode functional groups on electroactive bacteria through the whole biofilm formation process are summarized. In addition, the application of those modification technologies to improve bioelectricity generation, resource recovery, bioelectrochemical analysis and the production of value-added chemicals and biofuels is also discussed. Accordingly, this review aims to help scientists select the most appropriate functional groups and up-to-date methods to improve biofilm formation.

Graphical Abstract

Keywords:

• Functional group
• electron transfer
• biofilms
• bioelectrochemical systems
• surface modification
• electricity generation
• biofuels
• energy

Disclosure statement

The authors report that they have no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [No. 51778562, No. 51478414] and the National Key Research and Development Plan [2016YFB0600505].