A solar-powered microbial electrolysis cell with a platinum catalyst-free cathode to produce hydrogen.
ABSTRACT This paper reports successful hydrogen evolution using a dye-sensitized solar cell (DSSC)-powered microbial electrolysis cell (MEC) without a Pt catalyst on the cathode, indicating a solution for the inherent drawbacks of conventional MECs, such as the need for an external bias and catalyst. DSSCs fabricated by assembling a ruthenium dye-loaded TiO(2) film and platinized FTO glass with an I(-)/I(3)(-) redox couple were demonstrated as an alternative bias (V(oc) = 0.65 V). Pt-loaded (0.3 mg Pt/cm(2)) electrodes with a Pt/C nanopowder showed relatively faster hydrogen production than the Pt-free electrodes, particularly at lower voltages. However, once the applied photovoltage exceeded a certain level (0.7 V), platinum did not have any additional effect on hydrogen evolution in the solar-powered MECs: hydrogen conversion efficiency was almost comparable for either the plain (71.3-77.0%) or Pt-loaded carbon felt (79.3-82.0%) at >0.7 V. In particular, the carbon nanopowder-coated electrode without Pt showed significantly enhanced performance compared to the plain electrode, which indicates efficient electrohydrogenesis, even without Pt by enhancing the surface area. As the applied photovoltage was increased, anodic methanogenesis decreased gradually, resulting in increasing hydrogen yield.
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ABSTRACT: Microbial electrolysis cells (MECs) are an electricity-mediated microbial bioelectrochemical technology, which is originally developed for high-efficiency biological hydrogen production from waste streams. Compared to traditional biological technologies, MECs can overcome thermodynamic limitations and achieve high-yield hydrogen production from wide range of organic matters at relatively mild conditions. This approach greatly reduces the electric energy cost for hydrogen production in contrast to direct water electrolysis. In addition to hydrogen production, MECs may also support several energetically unfavorable biological/chemical reactions. This unique advantage of MECs has led to several alternative applications such as chemicals synthesis, recalcitrant pollutants removal, resources recovery, bioelectrochemical research platform and biosensors, which have greatly broaden the application scopes of MECs. MECs are becoming a versatile platform technology and offer a new solution for emerging environmental issues related to waste streams treatment and energy and resource recovery. Different from previous reviews that mainly focus on hydrogen production, this paper provides an up-to-date review of all the new applications of MECs and their resulting performance, current challenges and prospects of future.Water Research 02/2014; Just accepted. · 4.66 Impact Factor
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ABSTRACT: Anaerobic ammonium oxidation with an anode as the electron acceptor was realized in a dual-chamber microbial electrolysis cell (MEC). Nitrate was the main product that accounted for approximately 95% of ammonium consumed, but nitrite was also detectable. Using 16S ribosomal RNA analysis, we found that the microbial community attached to the electrode was dominated by Nitrosomonas europaea (40.3%) and the genus Empedobacter (34.7%), but no anammox bacteria were detected. Nitrosomonas europaea was shown to be necessary with an inhibition assay using allylthiourea. Certain soluble metabolites were found to have an important effect on the current production. These results show that there are many ways to oxidize ammonium biologically.Environmental Microbiology Reports 02/2014; 6(1):100-5. · 3.26 Impact Factor
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ABSTRACT: The Microbial Electrolysis Cell (MEC) biocathode has shown great potential as alternative for expensive metals as catalyst for H2 synthesis. Here, the bacterial communities at the biocathode of 5 hydrogen producing MECs using molecular techniques were characterized. The setups differed in design (large versus small) including electrode material and flow path and in carbon source provided at the cathode (bicarbonate or acetate). A hydrogenase gene-based DNA microarray (Hydrogenase Chip) was used to analyze hydrogenase genes present in the 3 large setups. The small setups showed dominant groups of Firmicutes and two of the large setups showed dominant groups of Proteobacteria and Bacteroidetes. The third large setup received acetate but no sulfate (no sulfur source). In this setup an almost pure culture of a Promicromonospora sp. developed. Most of the hydrogenase genes detected were coding for bidirectional Hox-type hydrogenases, which have shown to be involved in cytoplasmatic H2 production.Enzyme and Microbial Technology 01/2014; · 2.59 Impact Factor