bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Synthesis of Efficient Composite Catalyst Based on Fe-N-C Catalyst and Platium for Oxygen Reaction Reduction
Authors: Zhang Xuelin , Hou Chenjun , Zhang Yujun , Zhang Yufeng , Liu Xiaowei 
Published: February 2020

Globally, because of the consumption of fossil fuel, the proton exchange membrane fuel cells (PEMFC) have received great attention. Among them, direct methanol fuel cells(DMFC) have been applied into many fields, such as computers, global positioning systems(GPS) and portable devices. Platinum catalysts are considered as one of the most efficient catalysts for the oxygen reduction reaction(ORR),which is one of the most essential processes for the DMFC. However, the low methanol resistance limits the application of Platinum catalyst in DMFC. Fe-N-C catalyst has an excellent methanol selectivity and showes a good ORR activitity with great potential as a non-precious metal catalyst. However, the performance of Fe-N-C catalysts is impossible to exceed that of Pt-based catalysts, leading to the irreplacebility of Pt catalyst in DMFC.As a result, the composite catalyst made by Fe-N-C catalyst and Platnum catalyst was synthesized and expected to take advantage of the high methanol resistance of Fe-N-C catalyst and brilliant ORR activity of Platinum catalyst.
Herein, we reported a synthesis of an efficient composite catalyst based on Fe-N-C catalyst and Pt catalyst. The Fe-N-C catalyst was gained as described by Piotr Zelenay. Furthermore, 50mg Fe-N-C catalyst dissolved into 12ml isopropanol and 48ml ethanediol was fixed with 4.42ml H2PtCl2-ethanediol solution with a density of 20mg/ml and stirred for 3h. After making the pH of the solution 12 by 1M NaOH-ethanediol and N2 injection for 10 min, the solution was put into the microwave to heat until 130-150 degrees. After cooling to the room temperature, the pH was set as 3 by 1M HNO3. The FeNC-Pt catalyst was obtained after filtration and freeze drying.
For RDE tests on the FeNC-Pt catalyst, the ink was prepared by mixing 3mg catalyst dissolved into 2.1ml isopropanol and 29µl Nafion, which was stirred for 40min to achieve a good dispersion. 7µl ink was coated on the surface of RDE, making the loading of Pt 20µg cm-2. The linear sweep voltammetry(LSV) tests were conducted at the speed of 1600rpm in O2 and N2 saturated 0.1M HClO4 solution respectively. The half-wave potential of FeNC-Pt catalysts was about 20mV higher than Pt-C catalyst(0.86V vs 0.84V), which proved a more efficient performance of FeNC-Pt catalyst. The electrochemical areas(ECA) of the catalysts were gained by cyclic voltammetry(CV) tests, and the FeNC-Pt catalyst showed a larger ECA than the Pt-C catalyst. The methanol resistance test was conducted in N2-saturated 0.5M H2SO4-0.5M CH3OH solution, and the FeNC-Pt catalyst showed a better performance.

Figure 1
Fe-N-C with Ultra-Low Pt Content Electrocatalyst for the Oxygen Reduction: Investigation of the Electrocatalytic Activity and Stability
Authors: Vasconcellos Carlos S. , Aggio Ricardo B , Galiote Nelson Alexandre , Lima Fabio H. B. 
Published: February 2020

The high platinum loadings in the cathode is a critical obstacle for the commercialization of H2/air PEM fuel cells. Earth-abundant Fe-N-C electrocatalysts are under focus due to their high electrocatalytic, but this material suffers from poor stability due to the carbon corrosion by the undesired H2O2 species that are formed in parallel to H2O1. Herein, Fe-N-C was utilized as support for the deposition of ultra-low amounts of Pt nanoparticles2,3. The obtained results showed an oxygen reduction activity very similar to the state-of-the-art carbon-supported platinum (20 wt.%), and a considerable increase in the stability when compared to pure Fe-N-C. The main features that control the stability of the synthesized electrocatalyst is discussed in this study. The results from this investigation may contribute to further advance in the development of cost-effective and durable ORR electrocatalysts for PEM fuel cells.
References

M. Ferrandon, X. Wang, A. J. Kropf, D. J. Myers, G. Wu, C. M. Johnston, P. Zelenay, Electrochim. Acta 110 (2013) 282 – 291.

A. K. Mechler, N. R. Sahraie, V. Armel, A. Zitolo, M. T. Sougrati, J. N. Schwammlein, D. J. Jones, and F. Jaouen, J. Electrochem. Soc. 165 (13) (2018) F1084 - F1091.

L. Chong, J. Wen, J. Kubal, F. G. Sen, J. Zou, J. Greeley, M. Chan, H. Barkholtz, W. Ding, D-J. Liu, Science 362 (2018) 1276–1281.

Acknowledgements
Authors gratefully acknowledge financial support from FAPESP (2013/16930-7, and 2016/13323-0), CNPq (306469/20162), and Capes.
On the Mechanism of Synergistic ORR in Pt@PGM-Free Catalyst
Authors: Liu Di-Jia , Chong Lina 
Published: February 2020

Maximizing the platinum utilization represents a critical research area in the commercial PEM fuel cell development. This is particularly true at the fuel cell cathode where to promote sluggish oxygen reduction reaction (ORR) requires three to four times more Pt in the catalyst than its counterpart in anode. In the electrode, Pt should be highly dispersed to be fully accessible by the reactants. This becomes more important at the high fuel cell current density domain where a large influx of O2 must be converted. By simply dispersing platinum to smaller nanoparticles (NPs) has its limitation. Past studies indicate that the ideal NPs should have dimension in between 4 nm to 6 nm to balance the needs between high Pt exposure and low dissolution rate. At ultralow cathode loading of 0.03 mgPt/cm2 to 0.06 mgPt/cm2 in the PEM fuel cell, such size requirement adds a significant constraint to the available number of NPs for the effective oxygen conversion.
At Argonne National Laboratory, we recently developed a new type of ORR catalyst by integrating ultralow loading of Pt (~3 wt.%) over PGM-free catalytically active support derived from the zeolitic imidazolate frameworks. [1] The new catalyst not only demonstrated excellent platinum mass activity and polarization current density in PEM fuel cell test at the cathodic Pt loading < 0.04 mg/cm2, but also showed very good durability during multiple fuel cell voltage cycling in the accelerated stress test (AST). Various characterization tools including XPS, XRD, XAS, TEM have identified the new catalyst containing highly strained Pt-Co core-shell NPs over hig-density and uniformly distributed Co/N/C and Co@graphene PGM-free active support. DFT calculation found two ORR catalytic routes over Pt and PGM-free active site with a crossover path at the formation of hydrogen peroxide, leading to synergistic catalysis.
In this presentation, I will discuss the synergistic catalysis from the catalyst design perspective, supported by our recent experimental observation. I will also share our thoughts on the new research direction of this approach.

Acknowledgement: This work is supported by U. S. Department of Energy, Fuel Cell Technologies Office through Office of Energy Efficiency and Renewable Energy. The works performed at Argonne National Laboratory’s Center for Nanoscale Materials, an U.S. Department of Energy Office of Science User Facility, is supported by Office of Science, U.S. Department of Energy under Contract DE-AC02-06CH11357.
[1] L. Chong, J. Wen, J. Kubal, F. G. Sen, J. Zou, J. Greeley, M. Chan, H. Barkholtz, W. Ding, and D.-J. Liu, “Ultralow-loading Platinum-Cobalt Fuel Cell Catalysts Derived from Imidazolate Frameworks,” Science 362, 1276 (2018).
Development of Combined Small-Angle X-Ray Scattering and Fluorescence Yield X-Ray Absorption Spectroscopy Measurement Systems for Characterization of Structural and Chemical Information of Pt Alloy Nanoparticle Catalyst
Authors: Watanabe Takeshi , Hiraoka Yuji , Suda Kohei , Kawamoto Teppei , Yano Hiroshi , Inukai Junji , Hirosawa Ichiro 
Published: February 2020

The understanding of the structural and the chemical properties of Pt catalysts in polymer electrolyte fuel cells (PEFCs) is necessary to improve the activity for the durability of the catalysts. The small-angle X-ray scattering (SAXS) and the X-ray absorption spectroscopy (XAS) measurements are widely used to investigate the properties of Pt catalysts. Recently, Povia et al developed a powerful tool by combining the SAXS and XAS measurements for the characterization of the Pt nanoparticle catalysts [1]. However, this technique is difficult to investigate the chemical states of the low-concentrated catalysts. In this study, we developed the combined SAXS and the fluorescence-yield (FY) XAS measurement systems to investigate the structural and the chemical properties of low-concentrated catalysts.
The combined SAXS-FYXAS measurement system was developed at BL19B2 in SPring-8. For the XAS measurements, the Pt LⅢ edge was used. The ionization chamber and a single-element Ge solid state detector were used to obtain the FYXAS spectra. For the SAXS measurements, the X-ray energy was set to 11.5 keV and 11.55 keV, which are below and near to the Pt LⅢ absorption edge, respectively. The scattered X-ray was detected using an area detector (PILATUS 2M). The PtCo alloy nanoparticle for the oxygen reduction reaction was used as the sample in this experiment.
As the result, we could demonstrate the combined SAXS-FYXAS measurement systems. We will discuss the degradation mechanism of the PtCo alloy nanoparticle catalyst from both SAXS and FYXAS data.
[1] M. Povia et al. ACS. Catal., 8, 7000 (2018).
Effect of Hydrogen Sulphide Contamination on Platinum Catalyst Degradation in Polymer Electrolyte Membrane Fuel Cells
Authors: Dushina Anastasia , Wagner Peter , Dyck Alexander 
Published: February 2020

Platinum catalysts are widely used as electrocatalysts in polymer electrolyte membrane fuel cells (PEMFC). However, there are many factors that may lead to their degradation in PEMFC and one of them are impurities, which can penetrate the cell together with the feeding gases and then poison the catalyst [1]. Sulfur contaminants are strong undesirable poisons for the fuel cell even though they are usually present at very low levels (up to 5 ppm) in both fuel and air streams [2]. Hydrogen sulfide can adsorb onto platinum and affect the catalyst performance causing the loss of mass activity [3].
In this work the influence of H2S contamination on commercially available Pt catalyst with carbon support was studied by means of rotating ring-disk electrode experiments in perchloric acid. Accelerated stress testing (AST) was performed in terms of potential cycling up to 10.000 cycles in the absence of contaminants and in the presence of H2S for comparison. Cyclic voltammetry technique in terms of hydrogen under potential deposition (HUPD) and CO stripping was employed in order to determine the electrochemical surface area (ECSA). Oxygen reduction reaction (ORR) was used to identify kinetic parameters including kinetic limited current, Tafel slopes, mass and specific activity of the catalyst before and after degradation.
After AST the platinum degradation was observed in the presence of the contaminant as well as in the absence of H2S. Highly reproducible measurements showed that derived from HUPD and CO methods ECSA in the presence of poisoning species was slightly higher in comparison to the ECSA obtained in the absence of contamination. In contrast, the calculated catalyst activity after stress test in the presence of contaminations dropped more significantly compared to the test without poisoning species. This fact may be attributed to the sulfur adsorption on the catalyst layer leading to morphology changes [3]. Moreover, the increased Tafel slopes after AST may be an indication of the changes of the ORR mechanism from a four electron reaction to a two electron process reaction.
[1] R. Borup, Chemical Reviews 107 (2007) 3904–3951.
[2] Fuel Cell Handbook, US Department of Energy (2008).
[3] R. Mohtadi et al., Electrochemical and Solid-State Letters 6 (2003) A272–A274.

Figure 1
Biocarbon from Sewage Sludge As Anode Catalyst for the Production of Bioelectricity in an MFC
Authors: García-Mayagoitia S. , Fernández-Luqueño F. , Morales-Acosta Diana , López-Valdez Fernando , Alonso-Lemus Ivonne Liliana , Escobar-Morales Beatriz , de la Torre Saenz Luis , Rodríguez-Varela F.J. 
Published: February 2020

Over the last few years, the use of novel anode carbon catalysts from biomass as raw materials in Microbial Fuel Cells (MFC) has been increasingly investigated due to their catalytic properties and low cost compared to noble metals such as Pt. Nevertheless, it is acknowledged that the use of a catalyst in an MFC is not sufficient to generate bioenergy. A biofilm of electroactive bacteria must be grown on the catalyst surface, forming a bioanode. The combination of catalyst and biofilm oxidizes organic matter contained in substrate, promotes the electron transfer kinetics and thus enhances the generation of bioelectricity.
In this work, a biosolid from waste water sewage sludge from the food industry has been pyrolyzed and activated with KOH in N2 atmosphere in order to obtain a biocarbon. The biocarbon has been further functionalized with methanol in different concentrations (0.15, 0.5 and 1.0 M) aiming to enhance its biocompatibility with electroactive Bacillus subtilis (B. subtilis), used as microorganism. With these components, bioanodes have been fabricated using gas diffusion carbon cloths on which a catalytic layer containing the biocarbon have been painted using the brush method, followed by the growth of a biofilm of B. subtilis for 6 days in broth media.
The biocarbon was physicochemically characterized by XRD, SEM-EDS and FESEM. XRD patterns indicate that the material is amorphous in nature with a broad (002) peak attributed to graphitic structures. Some reflections attributed to crystalline phases are also observed. EDS analysis shows the presence of C, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti and Fe in the biocarbon. On this matter, the biosolid shows a composition of 72.0, 18.96, 2.96 and 0.22 (wt. %) of C, O, Si and K, respectively. The biocarbon has a reduction in C content (29.23 wt. %), with an increase in O (23.54 wt. %) and K (17.29 wt. %), attributed to the activation with KOH.
Moreover, the biocarbon shows biocompatibility with B. subtilis as indicated by morphology analysis by FESEM. The biocarbon + B. subtilis bioanodes have been characterized in a half-cell with pharmaceutical waste water (PWW, pH= 6.1) as the electrolyte. The cyclic voltammograms (CVs) show their biocatalytic activity, generating a high current density from the PWW compared with the electrodes without biofilm.
The results indicate that biocarbons from waste water sewage sludge are promising catalysts for MFC anode applications, due to their biocompatibility with bacteria and because their chemical composition may enhance the microbial metabolism mechanism, enhancing the performance of the bioelectrochemical device.
A Non-Negligible Interface Effect for Alkaline Hydrogen Oxidation Reaction
Authors: Zhao Tonghui , Gong Mingxing , Wang Deli 
Published: February 2020

In alkaline medium, the slow kinetics of the anodic hydrogen oxidation reaction (HOR) hinders the development of alkaline membrane fuel cells (AMFCs). Therefore, it is of great significance to explore the mechanism of HOR from establishing the "structure-activity relationship" and researching the main factor influencing the activity of the catalyst. Generally accepted viewpoint is the hydrogen binding energy (HBE) theory, a main descriptor of the catalytic activity, and regulation of the binding energy usually could be achieved by controlling the lattice strain. In our research, by taking advantage of the difference in the atomic radius of the 3d transition metals, a trimetal model (Pd3M@Pt (M=Fe, Co, Cu) core-shell structure) is constructed to study the HOR through the tuning of stress shrink degrees. By step-by-step electrochemical monitoring method and surface-controlled technology, the phase changes in the cycle were regulated and analyzed. Interestingly, it shows that the low-valence M(OH)x species formed in the electrochemical cycle obviously influenced the HOR activity rather than the HBE change caused by lattice shrink, mainly ascribed to strengthen the adsorption of OHad species and accelerate the Volmer step (Had+OH-→H2O+e-+*, rate-determined step, RDS). Meanwhile, It's worth noting the mass activity (MA) and specific activity (SA) of Pd3Co@Pt are significantly improved compared with Pt/C, close to 4 and 2 times. This Pd3M@Pt core-shell structure also improves the utilization of Pt and facilitates the design of efficient HOR catalyst.
Figure 1. a) Schematic diagram of the mechanism exploration for HOR with the model of Pd3M@Pt (M=Fe, Co, Cu); b) CV curves of four core-shell structure catalysts

Keywords: Hydrogen Oxidation Reaction, Pd3M@Pt core-shell structure, low-valence M(OH)x species, interface effect

References:

Strmcnik D, Uchimura M, Wang C, et al. Nat. Chem., 2013, 5(4): 300.

Lu S, Zhuang Z. J. Am. Chem. Soc., 2017, 139(14): 5156-5163.

Li J, Ghoshal S, Bates M K, et al. Angew. Chem. Int. Edit., 2017, 56(49): 15594-15598.

Figure 1
Understanding the Mass Transfer and Diffusion Effects of Carbon-Dioxide Absorption with Reaction in an Anion Exchange Membrane
Authors: Divekar Ashutosh G , Antunes Christopher M , Yang-Neyerlin Ami C. , Pivovar Bryan S. , Herring Andrew M. 
Published: February 2020

Anion exchange membranes for fuel cell are a promising technology for stationary applications. The technology still needs to overcome certain challenges before they can be applied to vehicular applications. These challenges include enhancing the durability of the cell performance and a solution to carbon-dioxide poisoning problem. This work will focus on the carbon-dioxide issue. In the past couple of years, a lot of emphasis has been placed on understanding the effect of carbon-dioxide on the material or electrochemical characteristics of the membrane.1-3 We have investigated the effect of carbon-dioxide on ionic concentrations, conductivity and the morphological characteristics of the membrane. We have also studied the equilibrium carbonate-bicarbonate concentration at different temperatures.2 However, we haven’t investigated the physical quantities of carbon-dioxide absorption like mass-transfer coefficient and diffusivity of the CO2 through the membrane. Researchers have tried to assume classical mass transfer absorption models in their simulation works however no one has attempted to experimentally investigate these crucial properties.4 Therefore, this work will discuss absorption phenomenon from a chemical engineering point to shed more light on the CO2 problem. Here we have used CO2 sensors to track the absorption of CO2 at different conditions. We have also conducted segmented cell tests to spatially understand the spatial effects of CO2 absorption on current density and voltage in-situ fuel cell test. The data will be fit to models to better predict the CO2 absorption with chemical reaction.5, 6 Ultimately this would be very useful to modelers so they can incorporate these absorption models and come up with better ways to operate the fuel cell using ambient air(400 ppm CO2).
References:

H. Yanagi and K. Fukuta, ECS Transactions, 2008, 16, 257-262.

A. G. Divekar, B. S. Pivovar and A. M. Herring, ECS Transactions, 2018, 86, 643-648.

A. G. Divekar, A. M. Park, Z. R. Owczarczyk, S. Seifert, B. S. Pivovar and A. M. Herring, ECS Transactions, 2017, 80, 1005-1011.

J. A. Wrubel, A. A. Peracchio, B. N. Cassenti, T. D. Myles, K. N. Grew and W. K. S. Chiu, Journal of The Electrochemical Society, 2017, 164, F1063-F1073.

V. A. Juvekar and M. M. Sharma, Chemical Engineering Science, 1973, 28, 825-837.

P. Danckwerts, Gas-liquid reactions, McGraw-Hill Book Co., 1970.
(Invited) Characterizing Performance Losses over Time in an Alkaline Exchange Membrane-Electrode Assembly By Electrochemical Impedance Spectroscopy
Authors: Amel Alina , Ashdot Aviv , Page Miles , Tal-Gutelmacher Ervin 
Published: February 2020

Anion exchange membrane fuel cells (AEMFC) are getting more and more attention in the last decade, due to their great potential as low cost electrochemical energy conversion systems. In the last years, great advancement were made in the performance of anion exchange membrane fuel cells.
With recent advances especially beginning-of-life power density showing that direct competition with proton exchange membrane fuel cell technology is indeed feasible, the durability of the alkaline Membrane-Electrode Assemblies (MEAs), which had been largely set aside in the community, comes into focus as perhaps the definitive remaining challenge of the technology .
In order to understand AEMFC performance losses, most of the characterization methods presented in the literature use ex-situ tools for post-mortem characterization, which are very effective especially in selecting material components (durability of membranes and membrane/ionomer chemistry, choice of Gas Diffusion Layers, mechanical stability of catalyst particles and catalyst layer morphologies, delamination, etc. However, the need for in-operando methods to follow performance losses in real time, and in real fuel cell hardware, can be satisfied using in-situ electrochemical impedance spectroscopy (EIS).
In this study we will present EIS measurements coupled with polarization curves collected during stability tests, while modifying operation parameters specially chosen to interrogate selected limitations, and study their evolution with time in fuel cell durability tests.
We focus especially on the influence of two features of the AEMFC: Mass transport loss modes, of which three are available: hydrogen, oxygen and – uniquely to the alkaline polymer electrolyte system – water, which is a reactant in the AEMFC cathode. Second, we examine the role of PtRu, by now a widely used alkaline HOR electrocatalyst that demonstrates high activity, but in some cases can be subject to activity loss via partial surface oxidation. This work demonstrates the opportunity to use EIS as a real time characterization tool towards improved understanding of AEMFC stability challenges.