Papers by Plamen Atanassov
This chapter describes a spray-based method to manufacture electrocatalyst powders for fuel cell ... more This chapter describes a spray-based method to manufacture electrocatalyst powders for fuel cell and related applications. The attributes of this process are compared to traditional solution precipitation/impregnation methods as well as non-powder-based electrocatalyst production methods. The spray-based process described here results in formation of unique spherical, micron-sized aggregates consisting of sub-micron electrocatalyst particles where the nanometer sized active phases (Pt, PtRu, metal alloys, metal oxides, composite and anchored molecular compounds) are highly dispersed on the surface of carbon supports. The advantages of this method to manufacture electrocatalyst powders are described in terms of process economics and performance.
Bioelectrochemistry (Amsterdam, Netherlands), Jan 14, 2015
Pyrroloquinoline quinone dependent soluble glucose dehydrogenase (PQQ-sGDH) enzymatic MWCNT elect... more Pyrroloquinoline quinone dependent soluble glucose dehydrogenase (PQQ-sGDH) enzymatic MWCNT electrodes were p roduced using 1-pyrenecarboxylic acid (PCA) activated through carbodiimide functionalization and 1-Pyrenebutyric acid N-hydroxysuccinimide ester (PBSE) as tethering agents. At 600mV potential, the current density generated by the activated-PCA tethered PQQ-sGDH anode was significantly greater than the current density generated by the untethered PQQ-sGDH and PBSE tethered anodes, and performance was nearly identical to the performance of a covalently bound PQQ-sGDH anode. A technique for covalently bonding heme-b (hemin), a natural quinohemoprotein porphyrin redox cofactor, to carbon nanotubes modified with arylamine groups is reported. The resulting performance of the covalently bound hemin PQQ-sGDH anode is considerably higher than that of any other PQQ-sGDH anodes tested.
Journal of the American Chemical Society, Jan 24, 2015
In this study, the influence of two quinones (1,2- and 1,4-benzoquinone) on the operation and mec... more In this study, the influence of two quinones (1,2- and 1,4-benzoquinone) on the operation and mechanism of electron transfer in PQQ-dependent glucose dehydrogenase (PQQ-sGDH) anodes has been determined. Benzoquinones were experimentally explored as mediators present in the electrolyte. The electrochemical performance of the PQQ-sGDH anodes with and without the mediators was examined and for the first time molecular docking simulations were used to gain a fundamental understanding to explain the role of the mediator molecules in the design and operation of the enzymatic electrodes. It was proposed that the higher performance of the PQQ-sGDH anodes in the presence of 1,2- and 1,4-benzoquinones introduced in the solution is due to the shorter distance between these molecules and PQQ in the enzymatic molecule. It was also hypothesized that when 1,4-benzoquinone is adsorbed on a carbon support, it would play the dual role of a mediator and an orienting agent. At the same time, when 1,2-b...
Physical Chemistry Chemical Physics, 2014
The last decade of research has made significant strides toward practical applications of Microbi... more The last decade of research has made significant strides toward practical applications of Microbial Fuel Cells (MFCs); however, design improvements and operational optimization cannot be realized without equally considering engineering designs and biological interfacial reactions. In this study, the main factors contributing to MFCs' overall performance and their influence on MFC reproducibility are discussed. Two statistical approaches were used to create a map of MFC components and their expanded uncertainties, principal component analysis (PCA) and uncertainty of measurement results (UMR). PCA was used to identify the major factors influencing MFCs and to determine their ascendency over MFC operational characteristics statistically. UMR was applied to evaluate the factors' uncertainties and estimate their level of contribution to the final irreproducibility. In order to simplify the presentation and concentrate on the MFC components, only results from Shewanella spp. were included; however, a similar analysis could be applied for any DMRB or microbial community. The performed PCA/UMR analyses suggest that better reproducibility of MFC performance can be achieved through improved design parameters. This approach is exactly opposite to the MFC optimization and scale up approach, which should start with improving the bacteria-electrode interactions and applying these findings to well-designed systems.
Bioelectrochemistry (Amsterdam, Netherlands), Jan 6, 2015
Self-assembled monolayers (SAMs) modified gold anodes are used in single chamber microbial fuel c... more Self-assembled monolayers (SAMs) modified gold anodes are used in single chamber microbial fuel cells for organic removal and electricity generation. Hydrophilic (N(CH3)3(+), OH, COOH) and hydrophobic (CH3) SAMs are examined for their effect on bacterial attachment, current and power output. The different substratum chemistry affects the community composition of the electrochemically active biofilm formed and thus the current and power output. Of the four SAM-modified anodes tested, N(CH3)3(+) results in the shortest start up time (15days), highest current achieved (225μAcm(-2)) and highest MFC power density (40μWcm(-2)), followed by COOH (150μAcm(-2) and 37μWcm(-2)) and OH (83μAcm(-2) and 27μWcm(-2)) SAMs. Hydrophobic SAM decreases electrochemically active bacteria attachment and anode performance in comparison to hydrophilic SAMs (CH3 modified anodes 7μAcm(-2) anodic current and 1.2μWcm(-2) MFC's power density). A consortium of Clostridia and δ-Proteobacteria is found on all t...
Journal of The Electrochemical Society, 2010
... Christopher A. Apblett, David Ingersoll, Sarang Sarangapani, Michael Kelly, Plamen Atanassov.... more ... Christopher A. Apblett, David Ingersoll, Sarang Sarangapani, Michael Kelly, Plamen Atanassov. Abstract. ... Commun., 8, 1204 (2006). C.Rice, RIMasel, P.Waszczuk, A.Wieckowski, and T.Barnard, J. Power Sources, 111, 83 (2002). ...
Journal of Power Sources, 2006
The construction and performance of a small-scale fuel cell using traditional catalysts and membr... more The construction and performance of a small-scale fuel cell using traditional catalysts and membrane separators is discussed. Cell active area was 1cm×1cm, with a total unit cell volume of 0.3cm3 each. Under well-hydrated conditions running under hydrogen and oxygen, these cells demonstrated over 600mWcm−2 at 80°C. Design of flow fields and the requirements for water management showed that flow channels
Langmuir : the ACS journal of surfaces and colloids, Jan 16, 2015
The discrete wavelet transform (DWT) has found significant utility in process monitoring, filteri... more The discrete wavelet transform (DWT) has found significant utility in process monitoring, filtering, and feature isolation of SEM, AFM, and optical images. Current use of the DWT for surface analysis assumes initial knowledge of the sizes of the features of interest in order to effectively isolate and analyze surface components. Current methods do not adequately address complex, heterogeneous surfaces in which features across multiple size ranges are of interest. Further, in situations where structure-to-property relationships are desired, the identification of features relevant for the function of the material is necessary. In this work, the DWT is examined as a tool for quantitative, length-scale specific surface metrology without prior knowledge of relevant features or length-scales. A new method is explored for determination of the best wavelet basis to minimize variation in roughness and skewness measurements with respect to change in position and orientation of surface feature...
ECS Journal of Solid State Science and Technology, 2013
ABSTRACT This research aims to overcome kinetics, ohmic and mass transport limitations by improvi... more ABSTRACT This research aims to overcome kinetics, ohmic and mass transport limitations by improving the nanoarchitectured design of the catalytic layer and the mass transport system in order to improve the current output and stability of the bioanode.Carbon nanostructured material, the multiwalled carbon nanotube (MWNTs) paper (buckeye paper (BEP)), and the polymeric structure of chitosan-carbon nanotubes (CNTs) mixture are integrated in the design. Integration of these nanostructured materials with various enzymes-alcohol, lactate and glucose dehydrogenases (ADH, LDH and GDH respectively)-was performed and analyzed. Polymethylene green (PMG) is used as a catalyst toward the oxidation of NADH to NAD+. The GDH-based anodic interface showed the best performance in the static electrolytic cell as well as in the quasi-2D flow-fan cell. Michaelis-Menten analysis on the GDH-based bioanode showed an IMax = 3.382 ± 0.180 mA.cm−2 and KM = 17.5 ± 3.1 mM compared to IMax = 226.6 ± 10.1 μA.cm−2 and KM = 16.0 ± 2.5mM for ADH and, IMax = 53.4 ± 5.1 μA.cm−2 and KM = 6.6 ± 3.3 mM for LDH respectively (electrolytic cell). Stability studies showed the GDH- bioanode conserved ∼80% of its initial performance at 15 days and ∼65% at 30 days of dry storage at 4◦C.
Methods in molecular biology (Clifton, N.J.), 2013
Conductive materials functionalized with redox enzymes provide bioelectronic architectures with a... more Conductive materials functionalized with redox enzymes provide bioelectronic architectures with application to biological fuel cells and biosensors. Effective electron transfer between the enzyme (biocatalyst) and the conductive materials is imperative for function. Various nanostructured carbon materials are common electrode choices for these applications as both the materials' inherent conductivity and physical integrity aids optimal performance. The following chapter presents a method for the use of carbon nanotube buckypaper as a conductive architecture suitable for biocatalyst functionalization. In order to securely attach the biocatalyst to the carbon nanotube surface, the conductive buckypaper is modified with the heterobifunctional cross-linker, 1-pyrenebutanoic acid, succinimidyl ester. The technique effectively tethers the enzyme to the carbon nanotube which enhances bioelectrocatalysis, preserves the conductive nature of the carbon surface, and facilities direct elect...
Advanced Energy Materials, 2011
ABSTRACT Novel unsupported Pd-In catalysts with varied Pd:In ratio were synthesized by the sacrif... more ABSTRACT Novel unsupported Pd-In catalysts with varied Pd:In ratio were synthesized by the sacrificial support method (SSM). Catalysts were characterized by XRD, SEM, TEM and BET techniques. The electrochemical activity for the oxidation reactions of methanol, ethanol, ethylene glycol, and glycerol was evaluated in alkaline media. High surface area in the range of 40 m2 g− 1 was determined for all catalysts. The observed mass activity of PdIn3 for the oxidation of ethylene glycol and glycerol was significantly higher of any reported in the literature, making this material a state-of-the-art catalyst.
Electrochimica Acta, 2014
Reducing inhibition of interfacial electron transfer and the resulting impact on catalytic curren... more Reducing inhibition of interfacial electron transfer and the resulting impact on catalytic current of bilirubin oxidase (BOx) bio-cathodes is explored. Polymer coated multi-wall carbon nanotubes (MWNTs) were modified with "tethering" and "orienting" agents in order to provide stable immobilization and efficient enzyme orientation. 1pyrenebutanoic acid, succinimidyl ester (PBSE) was used as a cross-linker. BOx natural substrate, bilirubin, along with its artificial analogues, were explored as orienting agents. It was established that bilirubin/PBSE modified BOx cathodes showed approximately 0.4 and 3.2 times increase in current density compared to cathodes modified separately with either PBSE or bilirubin, respectively. In subsequent experiments the incorporation of PBSE and 2,5dimethyl-1-phenyl-1H-pyrrole-3-carbaldehyde, a functional analogue of bilirubin, into the MWNT matrix resulted in further increase in the generated current density of 2 -2.5 times compared to the hybrid bilirubin/PBSE modified cathode and 20 times higher in comparison with the unmodified BOx cathode. This significant enhancement of the cathode's performance is due to the concomitant covalent attachment and proper orientation of BOx leading to improved enzyme/electrode interactions.
Described in this work is an electrochemical evaluation of novel alkaline ionomers employed as ca... more Described in this work is an electrochemical evaluation of novel alkaline ionomers employed as catalyst binder for non-platinum group metal electrocatalysts based on cyanamide precursor. Electrochemical evaluation of the nonplatinum group metal (non-PGM) catalyst bound with the featured alkaline ionomer classes over a range of conditions gives insight into how they behave, as well as provide information on how the varying functionalities enhance or inhibit the rate of oxygen reduction. We are showing that the polymer backbone structure has a larger influence on facilitating favorable reaction kinetics than ionomer to catalysts ratio. The poly(sulfone)-derived ionomers result in a worse activity than electrocatalysts with Nafion® and poly(phenylene)-derived ionomers. They also exhibited more peroxide desorption and greater limitation in the mass transport regime. The poly(phenylene)-derived polymers performed in line with the benchmark ionomer, Nafion®. The poly(phenylene)derived ionomers show promise as fruitful line of research in establishing an anion-conducting ionomer for alkaline electrolyte fuel cells.
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Papers by Plamen Atanassov