bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sterically Protected N-Heterocyclic Polymers: Unlocking the Potential of Alkaline Anion Exchange Membrane-Based Electrochemical Devices
Authors: Peckham Timothy James , Gholamkhass Bobak , Britton Benjamin , Zhang Ben , Holdcroft Steven , Fortin Patrick 
Published: May 2020

There has been considerable interest in alkaline anion exchange membranes (AAEMs) for use in electrochemical applications such as water electrolyzers, reverse electrodialysis and fuel cells.1 However, development of AAEMs has long been hindered by the instability of commonly-used cationic groups (e.g., ammonium, phosphonium) under conditions of high pH and elevated temperature.
At Ionomr Innovations Inc, we have been developing AemionTM, derived from sterically protected, N-heterocyclic-based AEMs, which exhibits remarkably high stability under a variety of different conditions (e.g., pH, temperature). This includes results from both the ex-situ studies commonly found in literature as well as in-situ tests using electrochemical devices (e.g., AAEMFC, alkali water electrolysis) for which no equivalent durability has been found with other commercially available membranes. This presentation will cover some of work in both the ex-situ and in-situ characterization of these materials and progress in scaling them up to production levels.
1. J. R. Varcoe, R. C. T. Slade Fuel Cells 2005, 5, 187-200.
Effect of Solvent of Ionomer Dispersion on Porous Electrodes with Three Phase Boundary
Authors: Park Jong-Hyeok , Park Jin-Soo 
Published: May 2020

Electrichemically driven energy conversion devices requires anodic and cathodic reactions to complete their electrochemical cells. Recent energy conversion devices such as water electrolyzers or fuel cells is comprised of anodic and cathodic reactions in which gases, ions and electrons participate. In particular, the movement of proton or hydroxyl ions generated and consumed at two electrodes, i.e., anode and cathode, are essential to determine the reaction rates due to low mobility compared to electrons. Ions moved through ion conducting membranes should be transported inside electrodes to participate in anodic or cathodic reactions. Ion pathway is normally in liquid electrolyte. Regardless, the introduction of any aqueous phase in energy conversion devices causes many problems during fabrication, operation, maintenance, and so on. In addition, if gas penetration or gas evolution is one of phenomena taking place at electrodes, the electrodes should be porous. Thus, much efforts have been devoted to develop quasi-solid electrolytes such as gel polymer, ion conducting polymers, impregnation of ions in porous matrix and so on. Among the candidates, ion conducting polymers are quite often chosen as ion conducting media for energy conversion devices. The technique to introduce ion conducting polymers within electrodes for oxidation and reduction reactions is to solidify catalyst inks consisting of electrocatalyst, dispersion of ion exchangeable polymers, controlling solvents and additives by evaporation of all solvents in catalyst inks. Ion conducting polymers could be dispersed in various solvents. It causes different shapes of ion conducting polymers in solvents, for instance, cylindrical rods, a less-defined large particles, coils and so on. Such different types of ion conducting polymers form distinguished structure catalyst layers. In this study, the effect of solvents dispersing ion conducting polymers on the performance and durability of catalyst layers was investigated. Electrochemical characterization such as I-V polarization, cyclic voltammetry, impedance and so on and microscopic characterization such as SEM and TEM were carried out to evaluate the performance and durability of catalyst layers.
Acknowledgments
This research was supported by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT, & Future Planning(NRF-2019M3E6A1063677).
MnOx Modified Fiber-Shaped Co As an Efficient Catalyst for Hydrazine Electro-Oxidation
Authors: Norkus Eugenijus , Valuckytė Gitana , Zabielaitė Aušrinė , Balčiūnaitė Aldona , Šimkūnaitė Dijana , Vaičiūnienė Jūratė , Naruskevicius Leonas , Tamašauskaitė-Tamašiūnaitė Loreta 
Published: May 2020

In this study, MnOx modified fiber-shaped Co nanocomposites have been fabricated via electrochemical deposition with the aim to use them as electrocatalysts in direct hydrazine fuel cells (DHFCs). The electrocatalytic activity of the MnOx modified fiber-shaped Co nanocomposites towards the electro-oxidation of hydrazine in an alkaline medium has been investigated using cyclic voltammetry and chrono-techniques. Scanning Electron Microscopy, X-ray diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy have been used for the characterization of the surface morphology, structure and composition of the prepared catalysts.
It was found that the MnOx modified fiber-shaped Co nanocomposites have significantly higher catalytic activity towards the electro-oxidation of hydrazine as compared to that of the bare fiber-shaped Co. Moreover, modification of the fiber-shaped Co coating with MnOx leads to the rather pronounced shift in the hydrazine electro-oxidation potential to more negative potential region and is followed by a tremendous increase in the direct hydrazine oxidation rate as compared to that of the unmodified fiber-shaped Co coating. MnOx modified fiber-shaped Co nanocomposites seems to be an efficient anode catalyst for DHFCs.
Study on the Effect of Surface Area on the Oxygen Reduction Reaction Performance of Perovskite Catalyst for Lithium-Oxygen Batteries
Authors: Kim Ji Youn , Choi Yu Song , Ahn Tae-Young , Yu Hye-Ryeon , Cho Jang-Hyeon 
Published: May 2020

Lithium oxygen batteries have been recognized as one of the next-generation power sources, capable of supplying power for a long time even in an independent extreme environment. In spite of the theoretical advantage, Li-O2 batteries face technical and economic challenges that must be addressed to promote them as commercially variable technologies for future energy system. Above all, battery performance largely depends on the activities of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) of the cathode during discharge and charge, respectively. The undesirable overpotential caused by sluggish reaction kinetics associated with the ORR and OER greatly limit the current performance of Li-O2 batteries, which must be improved by efficient catalyzing the reactions. Among the numerous catalysts, perovskite oxides have attention for candidate electro catalyst for Li-O2 batteries due to their high electronic/ionic conductivity, high electrochemical stability, and catalytic activity. Especially, La0.6Sr0.4Co0.2Fe0.8O3(LSCF) is considered as a typical catalyst for Li-O2 batteries, which can provide high oxygen surface exchange coefficient for fast kinetics at the gas/electrode interface. The surface area is significantly related on the ORR and OER performance, which influences on the active area for reactions. In this study, we have tried to utilize a simple high energy ball milling process to investigate the electrochemical properties of LSCF catalyst. Through the BET analysis, it was confirmed that the specific area significantly was increased after ball milling due to the reduced particle size, obtaining the optimized milling time with the higher ORR performance. The electrochemical activities have been measured with rotating disk electrode (RRDE) method. Well-ball milled LSCF catalyst has resulted in the enlargement of specific surface area and increased defective sites, which improve the catalytic activity.
To investigate the influence of LSCF oxides on the ORR process, the performance of composite electrode with LSCF catalyst in LITFSI in ether solvents has been compared with a carbon based cathode (carbon nano tube(CM130)). From the discharge results, the composite electrode showed the superior performance as well as higher specific capacitance (more than 1.6 times) than carbon based electrode dye to the altered transport and reaction kinetics due to LSCF. In this study, we have proposed the processes of obtaining a catalyst with optimal electrochemical properties through a relatively simple process and applied it to electrode for lithium oxygen batteries.
Electrospun Platinum Group Metal Free Catalyst Powder/Nafion/PEO Cathodes for Hydrogen/Air Fuel Cells
Authors: Yarar Kaplan Begüm , Kang Narae , Pintauro Peter N. , Zulevi Barr , Serov Alexey 
Published: May 2020

In recent years, there has been considerable research on platimum-group-metal-free (PGM-free) catalysts as the cathode material for proton-exchange membrane (PEM) fuel cells [1]. Although the oxygen reduction activity of these type of catalysts is lower than Pt or Pt-based alloys, a higher loading of these inexpensive catalysts may be a good way to balance sluggish oxygen reduction kinetics. One serious draw back of all PGM-free catalysts is their poor durability in a fuel cell. Pintauro and coworkers have shown the the durability issue can be solved using a cathode binder of Nafion® and poly(vinylidene fluoride), but the fuel cell power output was low [2]. In the present study, PGM-free cathode fabrication and performance are presented using particle/polymer electrospinning. Nanofiber mat cathodes with a catalyst loading of 1.0, 2.0, and 3.0 mg/cm2 were prepared using an iron based Fe-N-C catalyst (Pajarito Powder, NPC-2000), Nafion ionomer and poly (ethylene oxide) (PEO) as a carrier polymer for elelctrospinning. An SEM of one catalyst/Nafion fiber is shown in Figure 1. After removing PEO from a fiber mat by soaking in hot water, the nanofiber-based cathodes were incorporated into H2/air fuel cell membrane-electrode assemblies (MEAs) and their performance (power output and durability) was compared to that of conventional sprayed-cathode MEAs (with neat Nafion binder). The effects of fiber composition, thickness and the choice of solvent for electrospinning on fuel cell performance were also examined. The maximum power density of a PGM-free nanofiber-cathode MEA, was found to be 252 mW/cm2 at 80°C for H2 and air at 2 atm backpressure.

References:

1) Thompson, S.T.; Papageorgopoulos, D. Nat Catal
2, 558-561 (2019).
2) Slack, J.; Halevi, B.; McCool, G.; Li, J.; Pavlicek, R.; Wycisk, R.; Mukerjee, S.; Pintauro P. ChemElectroChem
5, 1537–1542 (2018)

Figure 1
Studies of Conditioning Protocols for Polymer Electrolyte Membrane Fuel Cells
Authors: Balogun Emmanuel 
Published: May 2020

For optimal performance, there is a need to condition the fuel cell when it is being used for the first time. This process of conditioning is referred to as initial conditioning, activation or break-in procedure. The goal behind the initial conditioning is to increase the performance of the fuel cell until it gets to its peak value for optimized operation. Although, the exact mechanism. During this conditioning process, the polymer membrane and the polymer in the catalyst layer network are hydrated; contaminants are removed from the catalyst, and the number of catalyst’s active sites increases, and finally, the fuel cells attain an optimized and stable performance at the end of this step. However, the whole process of conditioning is known to be very time consuming, with many state-of-the-art conditioning protocols taking in excess of tens of hours to attain peak performance. Thus, this further increases the operating cost of the PEMFC as considerable amount of gas is expended for this process.
In this report, a new conditioning protocol that entails a series of oxidative starving at the cathode is introduced to accelerate the conditioning process. Unlike prior conditioning protocol, this protocol focuses not just on the hydration of the membrane electrode assembly but on reclaiming dried and blocked catalyst sites on the cathode electrode. The performance after conditioning shows that this new protocol gives a 10% and 11% increase in output power in comparison with the standardized United States Department of Energy and European Union conditioning protocol. Also the new conditioning protocol was able to reach its peak performance in 30minutes in comparison to the United States Department of Energy and European Union conditioning protocol that takes over 5 hours and 11 hours respectively.
(Invited) Photoelectrochemical Solar Fuel Production Using Organic Semiconductors
Authors: Sivula Kevin 
Published: May 2020

Pi-conjugated carbon-based semiconductors are well-established as high-performance and easily-processed materials for inexpensive and scalable solar energy conversion in organic photovoltaic (OPV) devices, but their promise in the economic conversion of solar energy into chemical energy (solar fuels) has only recently been recognized. In this presentation, I will discuss the main approaches for employing organic semiconductor-based devices towards solar H2 generation via water splitting and review the state-of-the-art.[1] OPV-biased water electrolysis has advanced significantly, now exceeding 6% solar-to-hydrogen conversion efficiency. However, the direct water splitting by an organic semiconductor in a photoelectrochemical cell, which has attractive advantages, remains limited by the intrinsic stability of organic semiconductors when placed in direct junction with aqueous electrolyte. I will further present experimental insights into the operational stability of donor:acceptor bulk heterojunction photocathodes and photoanodes[2] with an organic/water interface. Using sacrificial redox couples and various electrochemical analysis including impedance spectroscopy we identify and quantify the key factors that govern long-term photoactivity (>12 h). These insights can be extended to overall water splitting with appropriate catalyst overlayer design. Overall our advances with organic semiconductor photoelectrodes open a new path for economically feasible solar fuel production.
[1] L. Yao, A. Rahmanudin, N. Guijarro, K. Sivula, Adv. Energy Mater.
2018, 1802585.
[2] P. Bornoz, M. S. Prévot, X. Yu, N. Guijarro, K. Sivula, J. Am. Chem. Soc.
2015, 137, 15338.
(Invited) Insights on Scale-up of BiVO4-Based Photoelectrochemical Water Splitting Devices
Authors: van de Krol Roel , Abdi Fatwa Firdaus 
Published: May 2020

With the STH efficiencies of metal oxide-based PV-PEC water splitting devices now approaching 10%, the next step is to move beyond laboratory experiments and demonstrate large area devices. We demonstrate an unbiased 50 cm2 PV-PEC water splitting device with an STH efficiency of 2.1%. While this is the highest reported value for a large-area BiVO4-based water splitting device, it is still a factor of ~3 below the 6.3% efficiency we achieve for the corresponding small-area device [1]. This illustrates that straightforward scale-up of spray-deposited BiVO4 photoanodes from <1 to 50 cm2 leads to significant efficiency losses. We studied the influences of variation in materials quality over larger areas, substrate conductivity, electrolyte conductivity, and cell geometry. At relatively modest photocurrent densities (2 - 3 mA/cm2), the total voltage losses amount to ca. 600 mV for our 50 cm2 device. The ohmic losses in the transparent conducting substrate (F-doped SnO2) represent only ~10% of the total losses. A much larger loss mechanism is due to mass transport limitations of the ionic species in the electrolyte. Specifically, we show that lateral diffusion in the direction parallel to the electrode surface plays a more important role that one would intuitively expect. We further quantified the different loss mechanisms using a combination of finite element analysis modeling (COMSOL Multiphysics®) and in-situ quantitative analysis of the fluid dynamics and pH of the electrolyte using particle image velocimetry and fluorescence techniques (Figure 1). This feedback mechanism between simulation and experiment allows a more accurate model construction and validation. Based on these insights, electrochemical engineering strategies to overcome the losses associated with scale-up are offered, which would limit the voltage loss for large-area devices to less than 50 mV.
References:
[1] I.Y. Ahmet, Y. Ma, J.W. Jang, T. Henschel, B. Stannowski, T. Lopes, A. Vilanova, A. Mendes, F.F. Abdi, R. van de Krol, “Demonstration of a 50 cm2 BiVO4 Tandem Photoelectrochemical-Photovoltaic Water Splitting Device”, Sust. Energy Fuels 3, 2366-2379 (2019).

Figure 1
(Invited) Virtual Analysis of Gas-Diffusion-Electrode CO2 Electrolyzers
Authors: Weng Lien-Chun , Bui Justin C. , Romiluyi Oyinkansola , Bell Alexis T. , Weber Adam Z. 
Published: May 2020

The electrochemical reduction of CO2 (CO2R) to value-added products is an attractive technology for tackling the rising atmospheric CO2 levels and storing intermittent renewable energy into chemical bonds. Fundamental understanding of CO2R has progressed significantly in recent years and is critical in the development of CO2R to liquid-fuel electrolyzers, where gas-diffusion electrodes (GDEs) have been shown to be key enabling architectures. Various designs have been proposed and studied in the literature to enhance overall selectivity, rates, and maximize the conversion of CO2, the latter of which is only now being recognized as a critical issue. In this respect, there is a need to explore the governing phenomena inherent in these architectures to enable optimization. Mathematical modeling is ideally suited to tackle and explore these multiphysics interactions and provide virtual design analysis.
In this talk, we discuss modeling methodologies and physics inherent in these devices and present our recent modeling of GDEs for CO2 reduction. We specifically examine the impacts of multiphase flow and related phenomena on overall cell performance. We then explore the performance and limitations of various cell designs guided by simulation results and examine potential methods for improving water management and tuning catalyst selectivity including the use of different anion-exchange and bipolar membranes. Finally, we discuss the disparities in local environments between aqueous and GDE devices and propose strategies to reduce the gap in knowledge between the two systems.
Acknowledgements
This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.
Probing the Boundary Layer of Electrochemical CO2 Reduction with Electrochemical Mass Spectroscopy
Authors: Tackett Brian M. , Moffat Thomas P 
Published: May 2020

Research into the aqueous electrochemical reduction of CO2 to fuels and commodity chemicals has grown quickly in conjunction with increasing concerns of greenhouse gas emissions and wider availability of “clean” electrons coming from solar and wind power. Reduction of CO2 to valuable multi-carbon products, such as ethylene or ethanol, has been observed on copper-based electrocatalysts, but many fundamental questions remain about such processes. Specifically, the nature of the active site under reaction conditions is unclear, due to possibilities for surface copper rearrangement,1 subsurface reactant species,2,3 and changes in local pH,4 among others. Here we attempt to deconvolute these process to gain a more fundamental understanding of this electrocatalytic reaction. We utilize a newly designed thin layer electrochemical mass spectrometer with 100% collection efficiency at fast time-scales5,6 to probe the product species in the boundary layer during electrochemical reduction of CO2 on copper-based electrocatalysts. We employ a range of electrode sizes to enable product sensitivity at low overpotentials and at high current densities. We combine these measurements with an analysis of pH at the surface to better understand the local pH changes as a function of reaction potential. These insights into boundary layer phenomena should guide future design of both selective catalysts and efficient device configuration for CO2 electroreduction.
References
1. C. M. Gunathunge et al., J. Phys. Chem. C, 121, 12337–12344 (2017) https://pubs.acs.org/doi/10.1021/acs.jpcc.7b03910.
2. M. Favaro, H. Xiao, T. Cheng, W. A. Goddard, and E. J. Crumlin, Proc. Natl. Acad. Sci. U. S. A., 114, 6706–6711 (2017).
3. T. M. T. Huynh and P. Broekmann, ChemElectroChem, 1, 1271–1274 (2014) http://doi.wiley.com/10.1002/celc.201402147.
4. N. Gupta, M. Gattrell, and B. MacDougall, J. Appl. Electrochem., 36, 161–172 (2006) https://doi.org/10.1007/s10800-005-9058-y.
5. D. B. Trimarco et al., Electrochim. Acta, 268, 520–530 (2018) https://www.sciencedirect.com/science/article/pii/S0013468618303438.
6. D. B. Trimarco, T. Pedersen, O. Hansen, I. Chorkendorff, and P. C. K. Vesborg, Rev. Sci. Instrum., 86, 075006 (2015) http://aip.scitation.org/doi/10.1063/1.4923453.
Fully Blossomed WO3/BiVO4 Structure Obtained Via Patterned Fto for Highly Efficient Water Splitting
Authors: Ju Sucheol , Lee Heon 
Published: May 2020

Photoelectrochemical (PEC) water splitting is an eco-friendly energy generation process that gives rise to a hydrogen source as a result of the redox reaction of water, using the energy of absorbed light. Because of the process involved, the overall efficiency is expressed as a product of the light absorption efficiency (ηabs), the charge separation efficiency (ηsep) and the charge transfer efficiency (ηtrans). PEC water splitting is difficult to commercialize because of its low efficiency and difficulty in applying to a large area. In order to alleviate these problems, considerable amount of research has gone into pattern to increase the efficiency of PEC itself and on the PEC-PSC tandem cell, which is the combination of a perovskite solar cell and PEC. However, until now, studies on applying pattern engineering to PEC have been restricted to the use of Au or Pt as electrodes. In this case, despite of gaining the advantage of the effect of pattern, it also has the disadvantages of being unsuitable of PEC-PSC tandem cell (due to the opacity of Au and Pt) and being impractical for application to the field of energy research (due to Au and Pt being very expensive).
In the work presented in the submitted manuscript, we have studied the increase in PEC efficiency by forming a patterned FTO. The patterned FTO, formed by direct printing, is transparent and cheaper than Au and Pt, making it a suitable electrode for applications in energy research as well as in a PEC-PSC tandem cell. It also has the desired effect of pattern. In the case of Au or Pt electrode, hydrothermal synthesis is of limited use as Au and Pt are detached due to the oxidation of Cr used as an adhesion layer. However, due to the high stability of FTO, hydrothermal synthesis is possible in our case.
we fabricated a flat Fluorine-doped SnO2 (FTO) electrode and a micro cone structured FTO electrode. We then fabricated a WO3 nanoflakes (NF)/BiVO4 photoanode on top of each of these two types of FTOs. The photocurrent density of WO3/BiVO4 on micro cone patterned FTO reached 1.50 mA/cm2 at 1.23 VRHE, which is 34 % higher than the that of WO3/BiVO4 on flat FTO(1.12 mA/cm2). When measured with 0.5 M Na2SO3, the photocurrent densities of FB-WO3/BiVO4 and B-WO3/BiVO4 were found to be 2.48 and 1.80 mA/cm2, respectively, at 1.23 VRHE. These results show the same trend as the (J – V) curve.
Our study was successful in increasing PEC efficiency by patterning transparent and cheap electrode materials (FTO), suitable for applications in PEC-PSC tandem cells, using direct printing. The significant advance demonstrated here indicates that it is possible to fabricate high efficiency PEC-PSC tandem cell using the FTO architecture, and to facilitate large-area PEC commercialization by using processes suitable for large-scale productions (namely direct printing, spray pyrolysis, and hydrothermal reaction).

Figure 1