Electricity Production in a Two Chamber Microbial Fuel Cell with Bioanodes and Biocathodes Catalyzed with Gold M. C. Na ´ jera 1 , L. Verea 2 , O. Lastres 2 , M. Mejı ´a-Lo ´pez 1 , J. Herna ´ ndez-Romano 3 , P. J. Sebastian 1 * 1 Instituto de Energı ´as Renovables, Universidad Nacional Auto ´ noma de Me ´xico, Temixco, 62580, Morelos, Me ´xico. 2 Instituto de Investigacio ´ n e Innovacio ´ n en Energı ´as Renovables, Universidad de Ciencias y Artes de Chiapas, Tuxtla Gutie ´rrez 29039, Chiapas, Me ´xico. 3 Universidad Polite ´cnica del Estado de Morelos, Jiutepec, 62574, Morelos, Me ´xico. Received March 09, 2020; accepted October 01, 2020; published online ¢¢¢ Abstract This work presents the study of different electrical potentials applied to a carbon cloth material to develop biofilms for their application as bioelectrodes in a microbial fuel cell (MFC). The principal aim of this work was to develop bio- anodes and biocathodes for their simultaneous operation in a MFC. The potentials applied were 0.1 V, 0.4 V, and –0.42 V vs. Ag/AgCl KCl reference electrode. Also, electrodes were studied, where a positive potential was applied and gold as the catalyst for oxygen reduction reaction (ORR) was used. The bioelectrodes were characterized with the cyclic voltammetry (CV) technique and the results determined the application of the bioelectrodes as bioanode or biocathode in the MFC. The biofilms formed were observed with the scan- ning electron microscopy (SEM) technique, and also a new type of electroactive bacteria (Sphingomonas paucimobilis) for biocathodes was identified with a molecular technique. The bioelectrodes developed were tested in a MFC and a maximum power density of 0.585 W m –2 was obtained. Keywords: Bioanode, Biocathode, Microbial Fuel Cell, Uncul- tured Shingommonas paucimobilis 1 Introduction The MFC is considered as an emerging energy technology, due to its capability to produce electrical energy from organic matter in wastewater. The maximum power density reported is 1.19 mW m –2 [1, 2]. However, the energy from this device is limited due to the electrode design which includes the elec- trode modification or the addition of the bacteria and other noble metal catalysts, such as Pt or non-noble metal catalysts like Fe and Mn [3]. The electrodes for MFC must be conductive and should be made of biocompatible materials, in order to support the bio- film made up of electroactive bacteria. Most of the investiga- tions reported are related to MFC with one bioelectrode (gen- erally a bioanode) and a cathode without a biofilm. Recently, researchers are more interested in MFC where both electrodes are bioelectrodes. The bioanode oxidizes the organic material in the medium and the biocathode reduces the oxygen. Actu- ally, the biofilm is considered as a catalyzer which is a very attractive alternative option instead of using precious metals [4–6], or to catalyze the cathode using nitrate, sulfate, chlor- oethene, fumarate, perchlorate and trichloroethene. Also, CO 2 , H + , Fe(lll), Cr(Vl), U(Vl), and Mn(lV) as electron acceptor and without the help of exogenous mediator [7–10]. The use of bio- cathodes in a MFC not only offers the advantage of not requir- ing expensive catalysts or mediators, but can also generate practical products or remove by-products through the micro- bial metabolism; for example CO 2 , which can be used by the algae for oxygen production in a two chamber MFC to improve the cathodic chamber performance [4, 11]. The carbon materials are currently the most widely used base electrode material for MFC, due to carbon’s high effi- ciency in heterogeneous electron transfer kinetics, biocompat- ibility and relatively low costs [1, 12]. – [ * ] Corresponding author, sjp@ier.unam.mx FUEL CELLS 00, 0000, No. 0, 1–7 ª 2020 Wiley-VCH GmbH 1 ORIGINAL RESEARCH PAPER DOI: 10.1002/fuce.202000051