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In this work, we initially report a detailed advancement in the utilization of metal-N4 chelate macrocycles in the oxygen reduction reaction (ORR). Then, iron(II) phthalocyanines supported on two different carbon-based supports specifically carbon nanotube and black pearl (carbon spheres) were synthesized and their activities toward ORR in alkaline media were studied. With the help of physical and surface characterization like Raman, BET, XRD, XPS, and electron microscopy analysis, the similarity in surface chemistry and surface area of the materials and the differences in the structure and morphology of the supports were established. This work also brings forth the effect of support properties on the electrocatalytic activity of the materials by a detailed electrochemical analysis using rotating disk electrode in oxygen saturated 0.1 M KOH. Comparison with existing literature on Fe-phthalocyanine supported on diverse carbon support is presented. [ABSTRACT FROM AUTHOR]

This work is presenting for the first time the use of inexpensive and efficient anode material for boosting power production, as well as improving electrofiltration of human urine in tubular microbial fuel cells (MFCs). The MFCs were constructed using unglazed ceramic clay functioning as the membrane and chassis. The study is looking into effective anodic surface modification by applying activated carbon micro-nanostructure onto carbon fibres that allows electrode packing without excessive enlargement of the electrode. The surface treatment of the carbon veil matrix resulted in 3.7 mW (52.9 W m−3 and 1626 mW m−2) of power generated and almost a 10-fold increase in the anodic current due to the doping as well as long-term stability in one year of continuous operation. The higher power output resulted in the synthesis of clear catholyte, thereby i) avoiding cathode fouling and contributing to the active splitting of both pH and ions and ii) transforming urine into a purified catholyte - 30% salt reduction - by electroosmotic drag, whilst generating - rather than consuming – electricity, and in a way demonstrating electrofiltration. For the purpose of future technology implementation , the importance of simultaneous increase in power generation, long-term stability over 1 year and efficient urine cleaning by using low-cost materials, is very promising and helps the technology enter the wider market. A new method for urine electrofiltration and long term power enhancement using surface modified anodes with activated carbon in ceramic microbial fuel cells Image 1 • Activated carbon modified anodes outperformed unmodified anodes. • Activated carbon modification increased the specific surface area. • Incisions in modified and unmodified anodes showed increase in power generation. • Good strategy for anode packing in miniaturised MFCs and long term stability. • MFCs with modified anodes generated clear catholyte from urine through electrofiltration. [ABSTRACT FROM AUTHOR]

We report the detection of volatile organic compound 1-cyclohexyl-2-pyrrolidone (CHP), in a bioelectrochemical system inoculated with Escherichia coli and supplemented with redox mediator 2-hydroxy-1,4-naphthoquinone (2-HNQ), using a functionalized carbon nanotube-coated screen-printed electrode (CNT-SPE) modified with –COOH and -NH 2 functional groups. Addition of CHP decreased current output of the bioelectrochemical system, thus enabling rapid detection of CHP concentration. Under optimal conditions, the H 2 N-CNT-SPE was the best performing and a limit of detection (LOD) of 0.4 mg L−1 was achieved. The proposed sensor showed low interference from other inorganic and organic components. These results outline a viable strategy for detecting organic contaminants in environmental monitoring applications. We report bioelectrochemical detection of 1-cyclohexyl-2-pyrrolidone (CHP), a volatile organic compound and a common contaminant in industrial wastewater using a carbon nanotubes-coated screen-printed electrode. The proposed sensor measures concentration of CHP through the variation of current output from Escherichia coli cells following exposure to CHP. Image 1 • A microbial-bioelectrochemical sensor was developed to detect 1-cyclohexyl-2-pyrrolidone (CHP). • Under optimal conditions, the limit of detection for CHP was 0.4 mg L−1. • The sensor has low cost, good reproducibility and is suitable for environmental monitoring. [ABSTRACT FROM AUTHOR]

Microbial desalination cell (MDC) is a bioelectrochemical system capable of oxidizing organics, generating electricity, while reducing the salinity content of brine streams. As it is designed, anion and cation exchange membranes play an important role on the selective removal of ions from the desalination chamber. In this work, sulfonated sodium (Na + ) poly(ether ether ketone) (SPEEK) cation exchange membranes (CEM) were tested in combination with quaternary ammonium chloride poly(2,6-dimethyl 1,4-phenylene oxide) (QAPPO) anion exchange membrane (AEM). Non-patterned and patterned (varying topographical features) CEMs were investigated and assessed in this work. The results were contrasted against a commercially available CEM. This work used real seawater from the Pacific Ocean in the desalination chamber. The results displayed a high desalination rate and power generation for all the membranes, with a maximum of 78.6 ± 2.0% in salinity reduction and 235 ± 7 mW m −2 in power generation for the MDCs with the SPEEK CEM. Desalination rate and power generation achieved are higher with synthesized SPEEK membranes when compared with an available commercial CEM. An optimized combination of these types of membranes substantially improves the performances of MDC, making the system more suitable for real applications. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cells (DMFCs) are promising electrochemical systems capable of producing electricity from the electrochemical oxidation of methanol and the reduction of oxygen. In this work, the effectiveness of the addition of sulfuric acid as a supporting electrolyte for methanol fuel composition was assessed. The results showed that the peak of power curve in DMFCs with Pt/C cathode electrocatalysts increased progressively from 70 mW cm−2 (0 mM of H 2 SO 4) to 115 mW cm−2 with a concentration of 100 mM of H 2 SO 4. These results underlined the positive effect of the addition of a supporting electrolyte in the methanol aqueous solution on the electrochemical output that was enhanced. Platinum group metal-free (PGM-free) electrocatalysts based on Fe-N x -C type were also tested being insensitive to methanol crossover and oxidation at the cathode. DMFC with Fe–N–C cathode catalysts result in a performance of 21.5 mW cm−2. In these operating conditions, the addition of supporting electrolyte does not seem to bring excessive advantage. Short stability tests are presented and an overall assessment of the resistances within the system is also discussed. • Addition of H 2 SO 4 in methanol feed boosts DMFC power density using Pt/C catalyst. • Power density is not dependent on H 2 SO 4 concentration using PGM-free catalyst for ORR. • Addition of H 2 SO 4 does not affect short-term cell performance. • Catalysts morphology and composition are not affected by H 2 SO 4 presence. [ABSTRACT FROM AUTHOR]

Mass generation of scrap tires presents a major challenge for environmental safety, however, their upcycling into carbon-based nanomaterials by the virtue of pyrolysis treatments can open up new windows for energy conversion and storage technologies in the context of the circular economy. Herein, we report the synthesis of Fe-N-C oxygen reduction reaction (ORR) electrocatalyst for fuel cell (FC) applications using carbonaceous char derived from scrap tires through microwave-assisted pyrolysis (MAP). The char obtained from MAP was activated with potassium hydroxide and then pyrolyzed at a high temperature to fabricate Fe-N-C after mixing with iron and nitrogen precursors. Finally, the developed Fe-N-C was ball-milled and acid-etched for homogenization and leaching of iron oxide nanoparticles. In this study, structural evaluation during each synthesis step was elucidated and correlated with the ORR activity in all three pHs i.e. acidic, neutral, and alkaline. Moreover, the effect of electrocatalyst loading on ORR kinetics was also analyzed using two different loadings (0.2 and 0.6 mg cm−2) on the rotating ring disk electrode (RRDE). The developed Fe-N-C demonstrated encouraging onset potentials of 0.881, 0.822, and 0.936 V vs RHE in acidic, neutral, and alkaline conditions, respectively. Whereas the ORR activity was slightly reduced after the milling-etching step. Lower peroxide yield together with a tetra-electronic reduction of oxygen was witnessed in acidic and neutral conditions, however, peroxide production was increased in the alkaline medium. [ABSTRACT FROM AUTHOR]

• Biochar produced from pyrolyzed waste tea leaves and activated with CO 2 or urea. • Fe-N-C electrocatalysts obtained by ball milling of biochar and Fe phthalocyanine. • Good ORR activity in alkaline environment and methanol tolerance, high durability. • Correlation of the ORR activity with porosity, biochar's functionality, Fe amount. Platinum metal group (PGM-free) electrocatalysts for oxygen reduction reaction (ORR) were synthesized by ball milling of activated biochar and Fe(II) phthalocyanine. The biochar used as a carbon support was produced from pyrolysis of waste tea leaves at 1500 °C in argon atmosphere. The pyrolyzed waste tea was then activated with CO 2 or urea. FE-SEM, HR-TEM, XPS, and Raman analyses were performed to investigate the morphology and the physicochemical properties of the electrocatalysts. The ORR activity and methanol tolerance of the Fe-N-C electrocatalysts were tested in rotating ring disk electrode (RRDE), showing promising results in terms of mass activity, onset and half-wave potential in an alkaline environment. Two different short potential cycling protocols demonstrated the high stability of these Fe-N-C electrocatalysts, especially when compared with a 20 wt. % commercial Pt/C electrocatalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Molecular imprinting polymer was used for low cost and easy-to-build bilirubin detection. • o -phenylenediamine was electropolymerized in the presence and absence of bilirubin. • Multiwalled carbon nanotubes were used for electrode modification before electropolymerization. • The electrochemical sensor exhibited high sensitivity and low detection limit. • The modified electrode was exploited for the selective detection of BR in saliva and serum of infants. In this study, molecular imprinting polymer (MIP) was used to develop selective active sites for low-cost and easy-to-build bilirubin (BR) detection because BR is known as an indicator of liver function. When the liver does not excrete BR properly, it causes jaundice, which is associated with liver diseases, especially in infants. High levels of BR can cause serious brain and spinal cord damage. Therefore, the identification and measurement of BR is important. In this study, the amount of BR in saliva was determined for the first time, which is non-invasive and cost-effective. Multi-walled carbon nanotubes (MWCNTs) were used for electrode modification before electropolymerization and MIP electrode preparation. o -phenylenediamine (OPD) was electropolymerized in the presence and absence of BR. The modified electrodes were characterized using different techniques. The electrochemical sensor exhibited an excellent selectivity and sensitivity, notably 1.05 µA fM−1. Moreover, the proposed sensor showed a wide linear range (12.08 fM to 91.81 fM) with a low detection limit of 7.80 fM. Moreover, the MIP electrode demonstrated acceptable operational stability (5% of signal loss over 10 days). After a deep characterization of the sensing platform, the MIP-modified electrode was utilized for the selective detection of BR in the saliva and serum of infants. [ABSTRACT FROM AUTHOR]

Bioelectrochemical systems combine electrodes and reactions driven by microorganisms for many different applications. The conversion of organic material in wastewater into electricity occurs in microbial fuel cells (MFCs). The power densities produced by MFCs are still too low for application. One way of increasing their performance is to combine them with electrochemical capacitors, widely used for charge storage purposes. Capacitive MFCs, i.e. the combination of capacitors and MFCs, allow for energy harvesting and storage and have shown to result in improved power densities, which facilitates the up scaling and application of the technology. This manuscript summarizes the state-of-the-art of combining capacitors with MFCs, starting with the theory and working principle of electrochemical capacitors. We address how different electrochemical measurements can be used to determine (bio)electrochemical capacitance and show how the measurement data can be interpreted. In addition, we present examples of the combination of electrochemical capacitors, both internal and external, that have been used to enhance MFC performance. Finally, we discuss the most promising applications and the main existing challenges for capacitive MFCs. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) has been linked to a vast array of vitamins among which vitamin B12 (Vit B12) is the most relevant and often investigated specially in the context of intrajejunal levodopa infusion therapy. Vit B12 deficiency, itself, has been reported to cause acute parkinsonism. Nevertheless, concrete mechanisms through which B12 deficiency interacts with PD in terms of pathophysiology, clinical manifestation and progression remains unclear. Recent studies have suggested that Vit B12 deficiency along with the induced hyperhomocysteinemia are correlated with specific PD phenotypes characterized with early postural instability and falls and more rapid motor progression, cognitive impairment, visual hallucinations and autonomic dysfunction. Specific clinical features such as polyneuropathy have also been linked to Vit B12 deficiency specifically in context of intrajejunal levodopa therapy. In this review, we explore the link between Vit B12 and PD in terms of physiopathology regarding dysfunctional neural pathways, neuropathological processes as well as reviewing the major clinical traits of Vit B12 deficiency in PD and Levodopa-mediated neuropathy. Finally, we provide an overview of the therapeutic effect of Vit B12 supplementation in PD and posit a practical guideline for Vit B12 testing and supplementation., Competing Interests: Declarations. Conflict of interest: All authors declare no financial or non-financial competing interests., (© 2024. The Author(s).)

Fe-N x -Cs being suitable to replace scarce and overpriced platinum group metals (PGMs) for cathodic oxygen reduction reaction (ORR) are gaining significant importance in the fuel cell arena. Although the typical sacrificial support method (SSM) ensures the superior electrocatalytic activity of derived Fe-N x -C, removing silica hard templates always remains a great challenge due to the hazardous use of highly toxic and not environmentally friendly hydrofluoric acid. Herein, strategic insight was given to modified SSM by exploiting the in-situ formation of HF, deriving from the decomposition of NH 4 HF 2 and NaF, to dissolve silica templates, thus avoiding the direct use of HF. First, the suitable molar ratio between the etching agent and the silica was analyzed, revealing that NH 4 HF 2 efficiently dissolved silica even in a stoichiometric amount, whereas an excess of NaF was required. However, both etching agents exhibited conformal removal of silica while dispersed active moieties within the highly porous architecture of derived electrocatalysts were left behind. Moreover, NH 4 HF 2 -washed counterparts demonstrated relatively higher performance both in acidic and alkaline media. Notably, with NH 4 HF 2 -washed Fe-N x -C electrocatalyst, a remarkable onset potential of 970 mV (vs RHE) was achieved with nearly tetra-electronic ORR as the peroxide yield remained less than 10 % in the alkaline medium., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

This study delves into the critical role of customized materials design and synthesis methods in influencing the performance of electrocatalysts for the oxygen reduction reaction (ORR) in anion exchange membrane fuel cells (AEMFCs). It introduces a novel approach to obtain platinum-free (PGM-free) electrocatalysts based on the controlled integration of iron active sites onto the surface of silica nanoparticles (NPs) by using nitrogen-based surface ligands. These NPs are used as hard templates to form tailored nanostructured electrocatalysts with an improved iron dispersion into the carbon matrix. By utilizing a wide array of analytical techniques including infrared and X-ray photoelectron spectroscopy techniques, X-ray diffraction and surface area measurements, this work provides insight into the physical parameters that are critical for ORR electrocatalysis with PGM-free electrocatalysts. The new catalysts showed a hierarchical structure containing a large portion of graphitic zones which contribute to the catalyst stability. They also had a high electrochemically active site density reaching 1.47 × 10 19 sites g -1 for SAFe_M_P1AP2 and 1.14 × 10 19 sites g -1 for SEFe_M_P1AP2, explaining the difference in performance in fuel cell measurements. These findings underscore the potential impact of a controlled materials design for advancing green energy applications.

In this manuscript, a comprehensive study is presented on Fe-based electrocatalysts with mono, bi, and tri-metallic compositions, emphasizing the influence of processing-structure correlations on the electrocatalytic activity for the oxygen reduction reaction (ORR) in the alkaline medium. These electrocatalysts were synthesized through the mixing of transition metal phthalocyanines (TM-Pc) with conductive carbon support, followed by controlled thermal treatment at specific temperatures (600 °C and 900 °C). An extensive analysis was conducted, employing various techniques, including X-ray Absorption Spectroscopy (XAS), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD), providing valuable insights into the structural characteristics of the synthesized nanoparticles. Importantly, an increase in the Fe-Pc weight percentage from 10% to 30% enhanced the ORR activity, although not proportionally. Furthermore, a comparative analysis between mono, bi, and tri-metallic samples subjected to different functionalization temperatures highlighted the superior electrocatalytic activity of electrocatalysts functionalized at 600 °C, particularly Fe 600 and Fe-Ni-Cu 600. These electrocatalysts featured E on values of 0.96 V vs. RHE and E 1/2 values of 0.9 V vs. RHE, with the added benefit of reduced anionic peroxide production. The potential of these Fe-based electrocatalysts to enhance ORR efficiency is underscored by this research, contributing to the development of more effective and sustainable electrocatalysts for energy conversion technologies.

Two-dimensional (2D) anatase titanium dioxide (TiO 2 ) is expected to exhibit different properties as compared to anatase nanocrystallites, due to its highly reactive exposed facets. However, access to 2D anatase TiO 2 is limited by the non-layered nature of the bulk crystal, which does not allow use of top-down chemical exfoliation. Large efforts have been dedicated to the growth of 2D anatase TiO 2 with high reactive facets by bottom-up approaches, which relies on the use of harmful chemical reagents. Here, we demonstrate a novel fluorine-free strategy based on topochemical conversion of 2D 1T-TiS 2 for the production of single crystalline 2D anatase TiO 2 , exposing the {001} facet on the top and bottom and {100} at the sides of the nanosheet. The exposure of these faces, with no additional defects or doping, gives rise to a significant activity enhancement in the hydrogen evolution reaction, as compared to commercially available Degussa P25 TiO 2 nanoparticles. Because of the strong potential of TiO 2 in many energy-based applications, our topochemical approach offers a low cost, green and mass scalable route for production of highly crystalline anatase TiO 2 with well controlled and highly reactive exposed facets., Competing Interests: Thee are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Self-stratifying microbial fuel cells with three different electrodes sizes and volumes were operated in supercapacitive mode. As the electrodes size increased, the equivalent series resistance decreased, and the overall power was enhanced (small: ESR = 7.2 Ω and P max  = 13 mW; large: ESR = 4.2 Ω and P max  = 22 mW). Power density referred to cathode geometric surface area and displacement volume of the electrolyte in the reactors. With regards to the electrode wet surface area, the large size electrodes (L-MFC) displayed the lowest power density (460 μW cm -2 ) whilst the small and medium size electrodes (S-MFC, M-MFC) showed higher densities (668 μW cm -2 and 633 μW cm -2 , respectively). With regard to the volumetric power densities the S-MFC, the M-MFC and the L-MFC had similar values (264 μW mL -1 , 265 μW mL -1 and 249 μW cm -1 , respectively). Power density normalised in terms of carbon weight utilised for fabricating MFC cathodes-electrodes showed high output for smaller electrode size MFC (5811 μW g -1 -C- and 3270 μW g -1 -C- for the S-MFC and L-MFC, respectively) due to the fact that electrodes were optimised for MFC operations and not supercapacitive discharges. Apparent capacitance was high at lower current pulses suggesting high faradaic contribution. The electrostatic contribution detected at high current pulses was quite low. The results obtained give rise to important possibilities of performance improvements by optimising the device design and the electrode fabrication., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s).)

Microbial fuel cells (MFCs) with paper separators and liquid containing elements were investigated in supercapacitive mode. MFCs (15 mL) in a supercapacitive configuration, consisted of plain wrapped carbon veil anode (negative) and conductive latex cathode (positive). The internal supercapacitor is discharged galvanostatically and is self-recharged as red-ox reactions occur on both electrodes. MFCs were discharged at different current pulses varying from 1 mA to 7 mA. The MFCs had an equivalent series resistance of 41.2 ± 3.5 Ω caused mainly by the cathode. A maximum power of 1.380 ± 0.083 mW (0.092 ± 0.006 mW mL -1 ) was measured. Durability tests were conducted over 24 h collecting 1000 discharge cycles (0.5 s) and self-recharges (85 s) at a current of 1 mA. Over time the anode potential dropped causing a decline in performance perhaps due to evaporation of liquid from the pyramidal structure. Resistance and apparent capacitance measured during the durability test remained approximately constant during the cycles., (© 2019 The Authors.)

Background: In this work, a small-scale ceramic microbial fuel cell (MFC) with a novel type of metal-carbon-derived electrocatalyst containing iron and nicarbazin (Fe-NCB) was developed, to enhance electricity generation from neat human urine. Substrate oxidation at the anode provides energy for the separation of ions and recovery from urine without any chemical or external power additions., Results: The catalyst was shown to be effective in clear electrolyte synthesis of high pH, compared with a range of carbon-based metal-free materials. Polarisation curves of tested MFCs showed up to 53% improvement (44.8 W m -3 ) in performance with the use of Fe-NCB catalyst.Catholyte production rate and pH directly increased with power performance while the conductivity decreased showing visually clear extracted liquid in the best-performing MFCs., Conclusions: Iron based catalyst Fe-NCB was shown to be a suitable electrocatalyst for the air-breathing cathode, improving power production from urine-fed MFCs. The results suggest electrochemical treatment through electro-osmotic drag while the electricity is produced and not consumed. Electro-osmotic production of clear catholyte is shown to extract water from urine against osmotic pressure. Recovering valuable resources from urine would help to transform energy intensive treatments to resource production, and will create opportunities for new technology development. © 2018 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

In recent years, the microbial fuel cell (MFC) technology has drawn the attention of the scientific community due to its ability to produce clean energy and treat different types of waste at the same time. Often, expensive catalysts are required to facilitate the oxygen reduction reaction (ORR) and this hinders their large-scale commercialisation. In this work, a novel iron-based catalyst (Fe-STR) synthesised from iron salt and streptomycin as a nitrogen-rich organic precursor was chemically, morphologically and electrochemically studied. The kinetics of Fe-STR with and without being doped with carbon nanotubes (CNT) was initially screened through rotating disk electrode (RDE) analysis. Then, the catalysts were integrated into air-breathing cathodes and placed into ceramic-type MFCs continuously fed with human urine. The half-wave potential showed the following trend Fe-STR > Fe-STR-CNT ≫ AC, indicating better kinetics towards ORR in the case of Fe-STR. In terms of MFC performance, the results showed that cathodes containing Fe-based catalyst outperformed AC-based cathodes after 3 months of operation. The long-term test reported that Fe-STR-based cathodes allow MFCs to reach a stable power output of 104.5 ± 0.0 μW cm -2 , 74% higher than AC-based cathodes (60.4 ± 3.9 μW cm -2 ). To the best of the Authors' knowledge, this power performance is the highest recorded from ceramic-type MFCs fed with human urine.

The scalability of bioelectrochemical systems is a key parameter for their practical implementation in the real-world. Up until now, only urine-fed self-stratifying microbial fuel cells (SSM-MFCs) have been shown to be scalable in width and length with limited power density losses. For practical reasons, the present work focuses on the scalability of SSM-MFCs in the one dimension that has not yet been investigated, namely height. Three different height conditions were considered (1 cm, 2 cm and 3 cm tall electrodes). The normalised power density of the 2 cm and 3 cm conditions were similar either during the durability test under a hydraulic retention time of ≈39 h (i.e. 15.74 ± 0.99 μW.cm -3 ) and during the polarisation experiments (i.e. 27.79 ± 0.92 μW.cm -3 ). Conversely, the 1 cm condition had lower power densities of 11.23 ± 0.07 μW.cm -3 and 17.73 ± 3.94 μW.cm -3 both during the durability test and the polarisation experiment, respectively. These results confirm that SSM-MFCs can be scaled in all 3 dimensions with minimal power density losses, with a minimum height threshold for the electrode comprised between 1 cm and 2 cm., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

A self-stratified microbial fuel cell fed with human urine with a total internal volume of 0.55 ml was investigated as an internal supercapacitor, for the first time. The internal self-stratification allowed the development of two zones within the cell volume. The oxidation reaction occurred on the bottom electrode (anode) and the reduction reaction on the top electrode (cathode). The electrodes were discharged galvanostatically at different currents and the two electrodes were able to recover their initial voltage value due to their red-ox reactions. Anode and cathode apparent capacitance was increased after introducing high surface area activated carbon embedded within the electrodes. Peak power produced was 1.20 ± 0.04 mW (2.19 ± 0.06 mW ml -1 ) for a pulse time of 0.01 s that decreased to 0.65 ± 0.02 mW (1.18 ± 0.04 mW ml -1 ) for longer pulse periods (5 s). Durability tests were conducted over 44 h with ≈2600 discharge/recharge cycles. In this relatively long-term test, the equivalent series resistance increased only by 10% and the apparent capacitance decreased by 18%.

In this work, benzimidazole (BZIM) and aminobenzimidazole (ABZIM) were used as organic-rich in nitrogen precursors during the synthesis of iron-nitrogen-carbon (Fe-N-C) based catalysts by sacrificial support method (SSM) technique. The catalysts obtained, denoted Fe-ABZIM and Fe-BZIM, were characterized morphologically and chemically through SEM, TEM, and XPS. Moreover, these catalysts were initially tested in rotating ring disk electrode (RRDE) configuration, resulting in similar high electrocatalytic activity toward oxygen reduction reaction (ORR) having low hydrogen peroxide generated (<3%). The ORR performance was significantly higher compared to activated carbon (AC) that was the control. The catalysts were then integrated into air-breathing (AB) and gas diffusion layer (GDL) cathode electrode and tested in operating microbial fuel cells (MFCs). The presence of Fe-N-C catalysts boosted the power output compared to AC cathode MFC. The AB-type cathode outperformed the GDL type cathode probably because of reduced catalyst layer flooding. The highest performance obtained in this work was 162 ± 3 μWcm -2 . Fe-ABZIM and Fe-BZIM had similar performance when incorporated to the same type of cathode configuration. Long-term operations show a decrease up to 50% of the performance in two months operations. Despite the power output decrease, the Fe-BZIM/Fe-ABZIM catalysts gave a significant advantage in fuel cell performance compared to the bare AC., Competing Interests: The authors declare no competing financial interest.

Iron(II) phthalocyanine (FePc) deposited onto two different carbonaceous supports was synthesized through an unconventional pyrolysis-free method. The obtained materials were studied in the oxygen reduction reaction (ORR) in neutral media through incorporation in an air-breathing cathode structure and tested in an operating microbial fuel cell (MFC) configuration. Rotating ring disk electrode (RRDE) analysis revealed high performances of the Fe-based catalysts compared with that of activated carbon (AC). The FePc supported on Black-Pearl carbon black [Fe-BP(N)] exhibits the highest performance in terms of its more positive onset potential, positive shift of the half-wave potential, and higher limiting current as well as the highest power density in the operating MFC of (243±7) μW cm -2 , which was 33 % higher than that of FePc supported on nitrogen-doped carbon nanotubes (Fe-CNT(N); 182±5 μW cm -2 ). The power density generated by Fe-BP(N) was 92 % higher than that of the MFC utilizing AC; therefore, the utilization of platinum group metal-free catalysts can boost the performances of MFCs significantly., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the past 10-15 years, the microbial fuel cell (MFC) technology has captured the attention of the scientific community for the possibility of transforming organic waste directly into electricity through microbially catalyzed anodic, and microbial/enzymatic/abiotic cathodic electrochemical reactions. In this review, several aspects of the technology are considered. Firstly, a brief history of abiotic to biological fuel cells and subsequently, microbial fuel cells is presented. Secondly, the development of the concept of microbial fuel cell into a wider range of derivative technologies, called bioelectrochemical systems, is described introducing briefly microbial electrolysis cells, microbial desalination cells and microbial electrosynthesis cells. The focus is then shifted to electroactive biofilms and electron transfer mechanisms involved with solid electrodes. Carbonaceous and metallic anode materials are then introduced, followed by an explanation of the electro catalysis of the oxygen reduction reaction and its behavior in neutral media, from recent studies. Cathode catalysts based on carbonaceous, platinum-group metal and platinum-group-metal-free materials are presented, along with membrane materials with a view to future directions. Finally, microbial fuel cell practical implementation, through the utilization of energy output for practical applications, is described.