Abstract
Grafting of aryldiazonium cations bearing a p-mannoside functionality over microbial fuel cell (MFC) anode materials was performed to investigate the ability of aryl-glycoside layers to regulate colonisation by biocatalytic biofilms. Covalent attachment was achieved via spontaneous reactions and via electrochemically-assisted grafting using potential step experiments. The effect of different functionalisation protocols on MFC performance is discussed in terms of changes in wettability, roughness and electrochemical response of modified electrodes. Water contact angle measurements (WCA) show that aryl-mannoside grafting yields a significant increase in hydrophilic character. Surface roughness determinations via atomic force microscopy (AFM) suggest a more disordered glycan adlayer when electrografting is used to facilitate chemisorption. MFCs were used as living sensors to successfully test the coated electrodes: the response of the MFCs in terms of start-up time was accelerated when compared to that of MFC equipped with non-modified electrodes, this suggests a faster development of a mature biofilm community resulting from aryldiazonium modifications, as confirmed by cyclic voltammetry of MFC anodes. These results therefore indicate that modification with glycans offers a bioinspired route to accelerating biofilm colonisation without any adverse effects on final MFC outputs.
Highlights
The discovery of electroactive microorganisms by Potter in 1911 [1,2] opened new frontiers in alternative energy technologies and environmental chemistry and led to the development of Microbial Fuel Cells (MFCs)
The characterization of aryl-glycoside adlayers prepared via aryldiazonium cation reactions at carbon and at a variety of other substrates has been reported in detail in previous work from our group [39,40,41,42,43,58,59]
We propose that the higher glycan densities achievable with electrografted methods are beneficial in presenting homogeneous mannoside adlayers at these highly rough electrode surfaces, in agreement with trends of increasing wettability observed via Water contact angle (WCA) measurements
Summary
The discovery of electroactive microorganisms by Potter in 1911 [1,2] opened new frontiers in alternative energy technologies and environmental chemistry and led to the development of Microbial Fuel Cells (MFCs). MFCs and related microbial bioelectrochemical systems, such as plant microbial fuel cells and microbial electrolysis cells, are some of the most interesting energy conversion devices with potential to facilitate the transition to a green economy. Colonisation of electrodes by suitable bacterial consortia and effective biofilm-electrode coupling are critical for the success of MFC devices and bioelectrochemical systems in general [5,6,7,8]. Munities and improving biofilm-electrode coupling have been the subject of intense investigation for the effective development of bioelectrochemical technologies and their further implementation beyond the laboratory [3,9,10]. Recent examples of interfacial electrode modifications explored include the use of inorganic nanoparticles and nanocarbons [6,8,11], nanopatterning and nanoroughness modifications [12], ionic liquids [13] and conductive polymers [8,14]
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