Papers by Kateryna Artyushkova
Journal of the Electrochemical Society
ChemSusChem
Iron(II) phthalocyanine (FePc) deposited onto two different carbonaceous supports was synthesized... more 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.
The Journal of Physical Chemistry C
Angewandte Chemie (International ed. in English), Jan 24, 2017
Ceria (CeO2 ) supports are unique in their ability to trap ionic platinum (Pt), providing excepti... more Ceria (CeO2 ) supports are unique in their ability to trap ionic platinum (Pt), providing exceptional stability for isolated single atoms of Pt. The reactivity and stability of single-atom Pt species was explored for the industrially important light alkane dehydrogenation reaction. The single-atom Pt/CeO2 catalysts are stable during propane dehydrogenation, but are not selective for propylene. DFT calculations show strong adsorption of the olefin produced, leading to further unwanted reactions. In contrast, when tin (Sn) is added to CeO2 , the single-atom Pt catalyst undergoes an activation phase where it transforms into Pt-Sn clusters under reaction conditions. Formation of small Pt-Sn clusters allows the catalyst to achieve high selectivity towards propylene because of facile desorption of the product. The CeO2 -supported Pt-Sn clusters are very stable, even during extended reaction at 680 °C. Coke formation is almost completely suppressed by adding water vapor to the feed. Furthe...
Applied catalysis. B, Environmental, Jan 15, 2017
Different iron-based cathode catalysts have been studied for oxygen reduction reaction (ORR) in n... more Different iron-based cathode catalysts have been studied for oxygen reduction reaction (ORR) in neutral media and then applied into microbial fuel cells (MFC). The catalysts have been synthesized using sacrificial support method (SSM) using eight different organic precursors named Niclosamide, Ricobendazole, Guanosine, Succinylsulfathiazole, Sulfacetamide, Quinine, Sulfadiazine and Pyrazinamide. Linear Sweep Voltammetry (LSV) curves were obtained for the catalysts using a O2 saturated in 0.1 M potassium phosphate buffer and 0.1 M KCl solution and a Rotating Ring Disk Electrode (RRDE) setup in order to study the ORR characteristics. Additionally, we analyze the peroxide yield obtained for each catalyst which helps us determine the reaction kinetics. Those catalysts have been mixed with activated carbon (AC), carbon black (CB) and PTFE and pressed on a metallic mesh forming a pellet-like gas diffusion electrode (GDE). Results showed that Fe-Ricobendazole, Fe-Niclosamide and Fe-Pyrazin...
Electrochimica Acta, 2017
The oxygen reduction reaction (ORR) is one of the major factors that is limiting the overall perf... more The oxygen reduction reaction (ORR) is one of the major factors that is limiting the overall performance output of microbial fuel cells (MFC). In this study, Platinum Group Metal-free (PGM-free) ORR catalysts based on Fe, Co, Ni, Mn and the same precursor (Aminoantipyrine, AAPyr) were synthesized using identical sacrificial support method (SSM). The catalysts were investigated for their electrochemical performance, and then integrated into an air-breathing cathode to be tested in "clean" environment and in a working microbial fuel cell (MFC). Their performances were also compared to activated carbon (AC) based cathode under similar conditions. Results showed that the addition of Mn, Fe, Co and Ni to AAPyr increased the performances compared to AC. Fe-AAPyr showed the highest open circuit potential (OCP) that was 0.307 ± 0.001 V (vs. Ag/AgCl) and the highest electrocatalytic activity at pH 7.5. On the contrary, AC had an OCP of 0.203 ± 0.002 V (vs. Ag/AgCl) and had the lowest electrochemical activity. In MFC, Fe-AAPyr also had the highest output of 251 ± 2.3 μWcm(-2), followed by Co-AAPyr with 196 ± 1.5 μWcm(-2), Ni-AAPyr with 171 ± 3.6 μWcm(-2), Mn-AAPyr with 160 ± 2.8 μWcm(-2) and AC 129 ± 4.2 μWcm(-2). The best performing catalyst (Fe-AAPyr) was then tested in MFC with increasing solution conductivity from 12.4 mScm(-1) to 63.1 mScm(-1). A maximum power density of 482 ± 5 μWcm(-2) was obtained with increasing solution conductivity, which is one of the highest values reported in the field.
ChemSusChem, 2017
Catalytic activity toward the oxygen reduction reaction (ORR) of platinum group metal-free (PGM-f... more Catalytic activity toward the oxygen reduction reaction (ORR) of platinum group metal-free (PGM-free) electrocatalysts integrated with an enzyme (bilirubin oxidase, BOx) in neutral media was studied. The effects of chemical and morphological characteristics of PGM-free materials on the enzyme enhancement of the overall ORR kinetics was investigated. The surface chemistry of the PGM-free catalyst was studied using X-ray Photoelectron Spectroscopy. Catalyst surface morphology was characterized using two independent methods: length-scale specific image analysis and nitrogen adsorption. Good agreement of macroscopic and microscopic morphological properties was found. Enhancement of ORR activity by the enzyme is influenced by chemistry and surface morphology of the catalyst itself. Catalysts with a higher nitrogen content, specifically pyridinic moieties, showed the greatest enhancement. Furthermore, catalysts with a higher fraction of surface roughness in the range of 3-5 nm exhibited greater performance enhancement than catalysts lacking features of this size.
Environmental science & technology, Jan 7, 2016
We investigated the reaction of manganese oxide [MnOx(s)] with phenol, aniline, and triclosan in ... more We investigated the reaction of manganese oxide [MnOx(s)] with phenol, aniline, and triclosan in batch experiments using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and aqueous chemistry measurements. Analyses of XPS high-resolution spectra suggest that the Mn(III) content increased 8-10% and the content of Mn(II) increased 12-15% in the surface of reacted MnOx(s) compared to the control, indicating that the oxidation of organic compounds causes the reduction of MnOx(s). Fitting of C 1s XPS spectra suggests an increase in the number of aromatic and aliphatic bonds for MnOx(s) reacted with organic compounds. The presence of 2.7% Cl in the MnOx(s) surface after reaction with triclosan was detected by XPS survey scans, while no Cl was detected in MnOx-phenol, MnOx-aniline, and MnOx-control. Raman spectra confirm the increased intensity of carbon features in MnOx(s) samples that reacted with organic compounds compared to unreacted MnOx(s). These spectroscopy results indi...
ChemSusChem, 2016
Catalytic oxidation of alcohols often requires the presence of expensive transition metals. Herei... more Catalytic oxidation of alcohols often requires the presence of expensive transition metals. Herein, it is shown that earth-abundant Fe atoms dispersed throughout a nitrogen-containing carbon matrix catalyze the oxidation of benzyl alcohol and 5-hydroxymethylfurfural by O2 in the aqueous phase. The activity of the catalyst can be regenerated by a mild treatment in H2 . An observed kinetic isotope effect indicates that β-H elimination from the alcohol is the kinetically relevant step in the mechanism, which can be accelerated by substituting Fe with Cu. Dispersed Cr, Co, and Ni also convert alcohols, demonstrating the general utility of metal-nitrogen-carbon materials for alcohol oxidation catalysis. Oxidation of aliphatic alcohols is substantially slower than that of aromatic alcohols, but addition of 2,2,6,6-tetramethyl-1-piperidinyloxy as a co-catalyst with Fe can significantly improve the reaction rate.
Environmental science & technology, Nov 1, 2016
We applied spectroscopy, microscopy, diffraction, and aqueous chemistry methods to investigate th... more We applied spectroscopy, microscopy, diffraction, and aqueous chemistry methods to investigate the persistence of metals in water and sediments from the Animas River 13 days after the Gold King Mine spill (August 5, 2015). The Upper Animas River watershed, located in San Juan Colorado, is heavily mineralized and impacted by acid mine drainage, with low pH water and elevated metal concentrations in sediments (108.4 ± 1.8 mg kg(-1) Pb, 32.4 ± 0.5 mg kg(-1) Cu, 729.6 ± 5.7 mg kg(-1) Zn, and 51 314.6 ± 295.4 mg kg(-1) Fe). Phosphate and nitrogen species were detected in water and sediment samples from Farmington, New Mexico, an intensive agricultural area downstream from the Animas River, while metal concentrations were low compared to those observed upstream. Solid-phase analyses of sediments suggest that Pb, Cu, and Zn are associated with metal-bearing jarosite and other minerals (e.g., clays, Fe-(oxy)hydroxides). The solubility of jarosite at near-neutral pH and biogeochemical proces...
Biointerphases, 2016
The structure and activity of electrochemically active biofilms (EABs) are usually investigated o... more The structure and activity of electrochemically active biofilms (EABs) are usually investigated on flat electrodes. However, real world applications such as wastewater treatment and bioelectrosynthesis require tridimensional electrodes to increase surface area and facilitate EAB attachment. The structure and activity of thick EABs grown on high surface area electrodes are difficult to characterize with electrochemical and microscopy methods. Here, the authors adopt a stacked electrode configuration to simulate the high surface and the tridimensional structure of an electrode for large-scale EAB applications. Each layer of the stacked electrode is independently characterized using confocal laser scanning microscopy (CLSM) and digital image processing. Shewanella oneidensis MR-1 biofilm on stacked carbon veil electrodes is grown under constant oxidative potentials (0, +200, and +400 mV versus Ag/AgCl) until a stable current output is obtained. The textural, aerial, and volumetric parameters extracted from CLSM images allow tracking of the evolution of morphological properties within the stacked electrodes. The electrode layers facing the bulk liquid show higher biovolumes compared with the inner layer of the stack. The electrochemical performance of S. oneidensis MR-1 is directly linked to the overall biofilm volume as well as connectivity between cell clusters.
Journal of the Electrochemical Society, 2014
In the past few decades of research, a significant progress has been achieved in the synthesis, p... more In the past few decades of research, a significant progress has been achieved in the synthesis, performance improvement, and understanding of the oxygen reduction reaction (ORR) mechanism on non-precious metal electrocatalysts. 1, 2 Among many attempted catalyst formulations, Co-N4 and Fe-N4 macrocycles (eg, porphyrins, phthalocyanines, Schiff bases and related derivatives), pyrolyzed at 500-1000 C in an inert atmosphere, have generally shown the highest catalytic activity in acid media. The activity is usually ...
Environmental science. Processes & impacts, Jan 26, 2016
The reactivity of metals associated with ash from wood collected from the Valles Caldera National... more The reactivity of metals associated with ash from wood collected from the Valles Caldera National Preserve, Jemez Mountains, New Mexico, was assessed through a series of laboratory experiments. Microscopy, spectroscopy, diffraction, and aqueous chemistry measurements were integrated to determine the chemical composition of wood ash and its effect on water chemistry. Climate change has caused dramatic impacts and stresses that have resulted in large-scale increases in wildfire activity in semi-arid areas of the world. Metals and other constituents associated with wildfire ash can be transported by storm event runoff and negatively affect the water quality in streams and rivers. Differences among ash from six tree species based on total concentrations of metals such as Ca, Al, Mg, Fe, and Mn were identified using non-metric multidimensional analysis. Metal-bearing carbonate and oxide phases were quantified by X-ray diffraction analyses and X-ray spectroscopy analyses. These metal-bear...
Meeting Abstracts, Aug 5, 2014
ABSTRACT Mechanism of the oxygen reduction reaction (ORR) is of particular importance to the desi... more ABSTRACT Mechanism of the oxygen reduction reaction (ORR) is of particular importance to the design and implementation of novel, non-platinum group metal (non-PGM) catalysts for various types of low temperature fuel cells. This paper will focus on the examples derived from the class of nano-structured materials composed of a transition metal, nitrogen and carbon, and often abbreviated as M-N-C.1 The synthesis of those materials usually involves pyrolysis, a high-temperature treatment in inert atmosphere, that leads to reactive decomposition of the catalysts precursor and forming of the active material. UNM has been developing an original method of catalyst synthesis that is based on templating of mono-dispersed of hierarchically structured silica particles: the sacrificial support method (SSM). This method allows producing catalysts with an open-frame morphology at the meso-scale and at the same time eliminates the “formal” support, thus the entire catalyst is the “active material”.2 During the pyrolysis the support ensures the catalyst dispersion and is responsible for the resulting high-surface area. After the pyrolysis, silica (the sacrificial support) is removed by dissolving in KOH or HF, resulting in self-supported M-N-C catalyst. We have demonstrated catalysts made by SSM derived from porphyrins2-5, heteroamines6,8 and polymers.7 We have studied these catalysts intensely by XPS2 and EXAFS/XANES4 and have made suggestions on the ORR mechanism.5,8 Exceptionally active catalysts were developed based on the SSM and derived from Fe salt and N-containing amines that do not form a complex with Fe in the precursor form. 9 Understanding of the nature of active sites in non-PGM catalysts is difficult due to high heterogeneity of such materials. SSM provides a unique opportunity to study the structure and reactivity of M-N-C catalysts as there is no “support effect” and the activity exceeds the state-of-the-art in non-PGM. All the M-N-C catalysts display plurality of active sites that have reactivity in ORR. Some of these sites support oxygen reduction to peroxide, some are active in peroxide reduction to water, some are active in both reactions and some may support a 4e- reduction of oxygen to water (see Fig. 1). In the actual catalyst a plurality of such moieties is presents and they all contribute to the integral activity. Transition metal appears to be required for the reduction of O2 to H2O(4 e- stoichiometry), yet there is no agreement on the mechanism (2 x 2 e- or 4 e-) and the number of active sites required for ORR completion. With the development of the understanding of which moieties participate in building particular active sites, the design paradigm for M-N-C shifts from the concept of placing as many low-active sites on the surface of the catalyst, to achieving the synthesis of extremely active site type(s), which are typically displayed at vey low surface concentrations. Achieving a single-site mechanism is possible when selectivity to O2 reduction and H2O2 reduction on both sites are similar. This, however does not automatically result in a “direct” 4 e- ORR mechanism. Such transition to 4 e- ORR on a single site can be achieved when H2O2 intermediate is converted to H2Ofaster than it is formed, implying design of a low selectivity site with high activity for H2O2 reduction. This paper will discuss both kinetics of ORR in alkaline and in acid media as well as the attribution of the active sites to different defects in graphene as active sites chemical structures. Acknowledgments: This work is supported by DOE-EERE Fuel Cell Technology Program: “Development of Novel Non Pt Group Metal Electrocatalysts for PEMFC” (S. Mukerjee, PI). References: * F. Jaouen et al., Energy Environ. Sci., 4 (2011) 114 * K. Artyushkova et al., Topics in Catalysis, 46 (2007) 263 * S. Pylypenko et al., Electrochimica Acta 53 (2008) 7875 * J.M. Ziegelbauer et al., J. Phys. Chem. C 112 (2008) 8839 * T.S. Olson et al., J. Electrochem. Soc. 157 (2010) B54 * A. Serov et al., Electrochem. Comm. 22 (2012) 53 * A. Serov et al., Appl. Catalysis B 127 (2012) 300 * M.H. Robson et al., Electrochim. Acta, 90 (2013) 656 * A. Serov et al., Adv. Energy Mat., (2014) DOI: 10.1002/aenm.201301735
ChemSusChem, Aug 4, 2016
Direct methanol fuel cells (DMFCs) offer great advantages for the supply of power with high effic... more Direct methanol fuel cells (DMFCs) offer great advantages for the supply of power with high efficiency and large energy density. The search for a cost-effective, active, stable and methanol-tolerant catalyst for the oxygen reduction reaction (ORR) is still a great challenge. In this work, platinum group metal-free (PGM-free) catalysts based on Fe-N-C are investigated in acidic medium. Post-treatment of the catalyst improves the ORR activity compared with previously published PGM-free formulations and shows an excellent tolerance to the presence of methanol. The feasibility for application in DMFC under a wide range of operating conditions is demonstrated, with a maximum power density of approximately 50 mW cm(-2) and a negligible methanol crossover effect on the performance. A review of the most recent PGM-free cathode formulations for DMFC indicates that this formulation leads to the highest performance at a low membrane-electrode assembly (MEA) cost. Moreover, a 100 h durability t...
ACS Applied Materials & Interfaces, 2016
Atomic layer deposition (ALD) is unsurpassed in its ability to create thin conformal coatings ove... more Atomic layer deposition (ALD) is unsurpassed in its ability to create thin conformal coatings over very rough and/or porous materials. Yet although the coating thickness on flat surfaces can be measured by ellipsometry, characterization of these coatings on rough surfaces is difficult. Here, two techniques are demonstrated to provide such characterization of ALD-coated TiO2 over mesoporous SnO2 aerogel films on glass substrates, and insights are gained as to the ALD process. First, X-ray photoelectron spectroscopy (XPS) is used to determine the coating thickness over the aerogel, and the results (0.04 nm/cycle) agree well with ellipsometry on flat surfaces up to a coating thickness limit of about 6 nm. Second, quantitative analysis of SEM images of the aerogel cross section is used to determine porosity and roughness, from which coating thickness can be inferred. The analysis reveals increasing porosity from the aerogel/air interface to the aerogel/substrate interface, indicating a thicker ALD coating near the air side, which is consistent with tortuous diffusion through the pores limiting access of ALD precursors to deeper parts of the film. SEM-derived porosity is generally useful in a thin film because bulk methods like nitrogen physisorption or mercury porosimetry are impractical for use with thin-film samples. Therefore, in this study SEM was also used to characterize quantitatively the morphologogical changes in SnO2 aerogel thin films due to doping with Sb. This study can be used as a methodology to understand morphological changes in different types of porous and/or rough materials.
Abstract: A method of preparing MNC catalysts utilizing a sacrificial support approach and inexpe... more Abstract: A method of preparing MNC catalysts utilizing a sacrificial support approach and inexpensive and readily available polymer precursors as the source of nitrogen and carbon is disclosed. Exemplary polymer precursors include non-porphyrin precursors with no initial catalytic activity. Examples of suitable non-catalytic non-porphyrin precursors include, but are not necessarily limited to low molecular weight precursors that form complexes with iron such as 4-aminoantipirine, phenylenediamine, hydroxysuccinimide, ethanolamine, and ...
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Papers by Kateryna Artyushkova