bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Validation of the Transmission Line Model Via Impedance Spectroscopy of an Ordered Array on Porous Carbon Electrode
Authors: Sharma Trishank , Díaz-Real Jesús Adrián , Zahiri Beniamin , Mérida Walter 
Published: February 2020

In this paper, the interface of a porous substrate with an arranged and well-defined geometry is investigated for the impedance response with different electrolytes by using the well known electrochemical technique of Electrochemical Impedance Spectroscopy (EIS). Based on De Levie's Transmission Line Model (TLM) for porous electrodes a modification has been done in the model by incorporating the CPE behavior to reflect the non-ideal behaviour for real electrodes at low frequencies. The geometry used to validate the proposed model was fabricated from a smooth Glassy carbon electrode (GCE) surface to correlate the EIS response to that obtained by the model. The desired array was obtained by using laser micromachining tool on a glassy carbon substrate with a goal to study the influence of different electrolytes, varying electrolyte concentrations, the morphological features of pore- depth and radii of pore as well as different pore shapes.
The outcomes of the experiments carried out on the in-house setup are compared with the MATLAB simulated results of the impedance. The transition from resistive to capacitive behavior is found to be shifted to lower frequency side and TLM behavior at high frequencies is more apparent as the concentration is increased. For the same concentration, different electrolytes are found to behave differently due to varying conductivity and ion sizes. In all the experiments carried out the impedance response showed CPE (constant phase element) behavior at the low frequency end while for high frequencies the nature/appearance of TLM behavior is found to be dependent on the pore depth to radius ratio. In addition the concept of time constant is also dealt with which exhibits differences for different geometries of the pores on glassy carbon. The results suggest that the GC electrode engaged here could provide a tractable model for studying electrochemical impedance behavior of porous electrodes without using any surface area analysis or pore volume analysis technique.

Keywords: Transmission Line Model, Glassy carbon, EIS, MATLAB
(Invited) Fabrication and Operation Under the Same Conditions: Oxygen Reduction on Cathodically Deposited Manganese Oxide
Authors: Pugolovkin Leonid V. , Levin Eduard E. , Savinova Elena R. , Tsirlina Galina A. 
Published: February 2020

We present the data on the oxygen reduction (ORR) and oxygen evolution (OER) in an alkaline solution for manganese oxide electrocatalysts fabricated by means of cathodic electrocrystallization. The catalysts are deposited from a permanganate alkaline bath, and later operate in the same 1 M NaOH medium. The effect of the deposition potential is addressed. The goal of the study is to obtain carbon-free oxide electrocatalysts with satisfactory activitiy and stability.
A qualitative difference of the electrochemical behavior is observed for oxides deposited at low (potentials above ~0.75 V RHE, region 1) and at higher overvoltage (potentials below ~0.75 V (RHE) region 2). Current efficiency is close to 40% in region 1, and increases up to 60% in region 2. All the samples consist of delta-MnO2 (birnessite), but their microstructure is essentially different for electrodeposition from regions 1 and 2. For the deposits fabricated in region 2 the birnessite structure is slightly distorted, while for the deposits prepared in region 1 a complete disordering along the layer stacking direction is observed.
The voltammograms of oxides in supporting electrolyte solution undergo fast evolution under potential cycling, accompanied by a decrease of the total charge. Stabilized voltammograms for the samples fabricated in region 2 are featureless and demonstrate a pronounced Ohmic contribution, while for the samples deposited in region 1 a reversible redox behavior is observed, with broad current peaks and formal potential of ~ 0.85 V RHE. The total charge is proportional to the oxide loading in the interval under study (~ 10 – 90 mkg/cm2). Both types of samples do not exhibit reductive degradation at potentials above 0.7 V (RHE).
ORR activities are estimated from the rotating disc electrode data in an O2-saturated solution. For oxides fabricated in region 1 the kinetic currents at 0.85 V RHE approach 40-50 A/g (for intermediate loadings), making them promising binder-free ORR catalysts. The ORR activity of oxides electrodeposited at higher overvoltages is an order of magnitude lower corroborating the influence of structure on the electrocatalytic activity. Even though the OER activities of electrodeposited oxides at 1.63 V RHE do not exceed 3 A/g, their remarkable stabilities both in the ORR and in the OER potential interval allows one to hope that these materials may be of interest as a component of hybrid bi-functional catalytic compositions together with other oxides more active in the OER.
The authors are grateful to Yu.A. Velikodnyi and A.Ye. Baranchikov for their help with structural characterization of the samples. The work is supported by EraNetRus program, project (#270 NANO-Morf).
An Investigation of the Adverse Effect of TiO2 on Pt-Catalyst for the Oxygen Reduction Reaction
Authors: Miller Todd , Mukerjee Sanjeev , Jia Qingying 
Published: February 2020

Northeastern University Center for Renewable Energy Technology (NUCRET), 317 Egan Center, Northeastern University, 360 Huntington Avenue, Boston, MA 02115
Metal oxides have long been used to protect carbon supports from corrosion on the anode side of a fuel cell during fuel starvation, when the metal oxides serve as a catalyst for water hydrolysis it protects the carbon supports from corrosion. Titanium dioxide (TiO2) is commonly used on the anode, and known to be effective at protecting the carbon from corrosion. However, we recently found that mechanically mixing Pt/C with some TiO2 as the anode catalyst of a PEMFC leads to a significant drop of the cell performance at a very early stage of operation. Subsequent efforts to understand the phenomenon led to the finding that the even a small amount of TiO2 seriously poison the Pt/C catalyst for the oxygen reduction reaction (ORR) by reducing the half wave potential by more than 150 mV (Figure 1), whereas the HOR rate was not significantly affected. By combing ex situ and in situ characterizations and detailed electrochemical testing, we provide solid experimental evidence for the unexpected TiOx–induced poisoning effect, which largely accounts for the activity loss. The new findings of the interactions between the Pt/C and the metal oxide help to pursue metal oxides that are better at protecting the carbon from corrosion while minimizing the poisoning effects.
Acknowledgement:
The authors gratefully acknowledge the financial support of Automotive Fuel Cell Corporation (AFCC), Canada and Ford Motor Co., Detroit, MI (under a URIP program). The authors also acknowledge instrumental support from Thermo Fisher Corp., and access to synchrotron based facility for x-ray absorption spectroscopy at National Synchrotron Light Source-II (NSLS-II) situated in Brookhaven National Laboratory (BNL), Upton, NY, under grant # DE-SC0012704

Figure 1
The Structural Effect of Pd-H Catalysts on Synthesizing Temperature for Direct Alkaline Formate Fuel Cell
Authors: Hong Sujik , Hwang Hongsun , Lee Jae Kwang , Lee Jaeyoung 
Published: February 2020

Direct liquid fuel cells (DLFCs) have been received much attention due to its safety, transportation, storage and utilization. Among them, the formate (HCOO-) as a fuel have more attracted due to its faster oxidation kinetics compared with formic acid (HCOOH) in optimal pH and higher theoretical voltage compared with the methanol and the ethanol.[1-3] Furthermore, the HCOO- has being predominant form in alkaline media and there has been no poisoning effect on palladium (Pd) catalyst on the oxidation of HCOO- such as carbon monoxide which is the inevitable species as the oxidation of formic acid and HCOO- on platinum (Pt). In the point of view of mechanistic study, decreasing the chemisorption strength of the adsorbed hydrogen (Hads) plays a key role in determining the enhanced catalytic activity of the oxidation of HCOO- on Pd, since the desorption of Hads is rate-determining step (RDS) of the oxidation of HCOO- on Pd so that it blocks an active site of the adsorption of HCOO-.[4] By alloying Pd and other transition metal such as copper (Cu) or gold (Au), the adsorption strength on Pd has been weakened through the d-band of Pd has been more filled due to the electron transfer from other transition metal to Pd.[5] In addition, the adsorption strength on Pd can be also weakened by the electronic effect that the d-band of Pd is more filled by electrons of heteroatoms such as hydrogen (H) and boron (B) entered to Pd lattice.[4,6]
In previous study [4], we had synthesized Pd-H catalyst on the carbon powder via sodium borohydride as a reducing agent and observed enhanced catalytic activity of the oxidation of HCOO- despite of the large particle size compared with that of commercial Pd/C. Because the morphology is also deeply related to the catalytic activity, we have investigated the correlation between structural changes such as dispersity or particle size and catalytic activity of the oxidation of HCOO- by controlling synthesizing temperature. In this study, we have synthesized Pd-H catalyst using a characteristic of lattice on the carbon powder of in accordance with temperatures and comparing their surface, particle size, crystal structure and catalytic activity of the oxidation of HCOO- using electrochemical method and physicochemical analysis.
Refrerences

J. Joo et al., ACS catalysis, 2015, 5, 6848.

S. Uhm et al., Angewandte Chemie, 2008, 120, 10317.

S. Uhm et al., Physical Chemistry Chemical Physics, 2009, 11, 9326.

M. Choun et al., Catalysis Today, 2017, 295, 26.

O. Yepez et al., International Journal of Hydrogen Energy, 2002, 27, 99.

C.W.A. Chan et al., Nature Communication, 2014, 5, 5787.

Figure 1
(Invited) Developing Electrocatalysts for Ethanol Oxidation Reaction in Alkaline Media
Authors: Cai Wen-Bin 
Published: February 2020

The ethanol oxidation reaction (EOR) has drawn increasing interest in electrocatalysis and fuel cells by considering that ethanol as a biomass fuel has advantages of low toxicity, renewability, and a high theoretical energy density compared to methanol. Alternatively, the ethanol electroreforming is a low energy cost technology that may produce valuable chemicals in the anode and clean hydrogen in the cathode at low temperature and atmospheric pressure. In both of the above energy conversion and storage technologies, the efficient oxidation of the ethanol in the anode by means of electrocatalysis is essential and the efficiency is largely determined by the chosen catalysts. Notably, in alkaline media both Pt and Pd show enhanced EOR activities.
The mechanistic investigation as well as the rational design of electrocatalysts are challenging yet essential for the desired complete oxidation to CO2, in considering that EOR is a complex multiple-electron process involving various intermediates and products. This talk starts with discussion on the mechanistic understanding of EOR on Pt and Pd surfaces using selected publications as examples. Consensuses from the mechanistic studies are that sufficient active surface sites to facilitate the cleavage of the C–C bond and the adsorption of water or its residue are critical for obtaining a higher electro-oxidation activity. I will then show by cases how this understanding has been applied to achieve improved performance on Pt- and Pd-based catalysts for EOR in alkaline media through optimizing electronic and bifunctional effects, as well as by tuning their surface composition and structure.

Acknowledgements
：Financial support from the NSFC (grant No. 21733004 and 21473039）and the 973 Program (No. 2015CB932303) of MOST is highly appreciated
References
[1] Y. Wang, S.Z. Zou, and W. B. Cai, Catalysts, 5, 1507 (2015).
[2] Y. Y. Yang, J. Ren, Q. X. Li, Z. Y. Zhou, S. G. Sun and W. B. Cai, ACS Catal., 4, 798(2014).
[3] H. Wang, K. Jiang, Q.L. Chen, Z.X. Xie, W.B. Cai, Chem. Commun., 52, 374(2016).
[4] T. T. Zhao, H. Wang, X. Han, K. Jiang, H. X. Lin, Z. X. Xie and W. B. Cai, J. Mater. Chem. A, 4, 15845 (2016).
[5] W. J. Huang, X. Y. Ma, H. Wang, R. F. Feng, J. G. Zhou, P. N. Duchesne, P. Zhang, F. J. Chen, N. Han, F.P. Zhao, J.H. Zhou, W.B. Cai and Y.G. Li, Adv. Mater. 29 (2017). DOI: 10.1002/adma.201703057.
[6] X.Y. Ma, Y.F. Chen, Q.X. Li, W.F. Lin, W.B. Cai, to be submitted.
Metal Ion Cycling of Cu Foil for Selective C-C Coupling in Electrochemical CO2 Reduction
Authors: Jiang Kun , Sandberg Robert , Chan Karen , Wang Haotian 
Published: February 2020

Electrocatalytic CO2 reduction to higher value hydrocarbons beyond C1 products is desirable for applications in energy storage, transportation, and the chemical industry. Cu catalysts have shown the potential to catalyze C-C coupling for C2+ products, but still suffer from low selectivity in water.1 Here we use density functional theory to determine the energetics of the initial C-C coupling steps on different Cu facets in CO2 reduction, and suggest that the Cu(100) and stepped (211) facets favor C2+ product formation over Cu(111). To demonstrate this we report the tuning of facet exposure on Cu foil through the metal ion battery cycling method. Compared to the polished Cu foil, our 100-cycled Cu nanocube catalyst with (100) facets exposed presents a 6-fold improvement in C2+ to C1 product ratio, with a highest C2+ Faradaic efficiency of over 60 % and H2 below 20 %, and a corresponding C2+ current of more than 40 mA/cm2.2

References:
(1) Hori, Y., Takahashi, I., Koga, O. & Hoshi, N. J. Mol. Catal. A Chem.
199, 39-47 (2003).
(2) Jiang, K., Sandberg, R.B., Akey, A.J., Liu, X., Bell, D.C., Nørskov, J.K., Chan, K. & Wang, H. Nat. Catal. in press (2018).
On-Chip Enzymatic Microbiofuel Cell-Powered Integrated Circuits
Authors: Mano Nicolas 
Published: February 2020

In situ energy harvesting is a major limitation for the development of implantable biomedical digital devices. Considerable efforts have been made to improve Glucose/O2 Enzymatic Biofuel Cells (EBFCs), able to generate electrical power in the physiological environment, in order to match the demands of biomedical electronics [1]. A key advance was the development of redox hydrogels. They permit efficient connection of high amounts of oxidoreductases to electrodes, leading to easily miniaturizable BFCs with power densities in the range of 100 μW.cm-2 suitable for application [2]. However, their open circuit potentials still fall below the requirements of conventional electronics. On the other hand, the power and voltage demands have decreased thanks to tremendous progress in low-power electronics [3], rendering devices compatible with the performance of EBFCs.
Here we demonstrate that common data processing functions such as binary counting can be powered by a glucose/O2 micro-EBFC directly integrated on an Application Specific Integrated Circuit (ASIC) at the die level. An EBFC based on Glucose Oxidase and Bilirubin Oxidase hydrogels immobilized on 400 μm diameter electrodes was designed on the Si chip of the 4-bit ripple-counter. The system could be continuously powered during several hours from a single 50 μL droplet of aerated 5mM glucose solution.
1] S. Cosnier, A. Le Goff, M. Holzinger, Electrochem. Comm., 2014, 38, 19-23.
[2] N. Mano, F. Mao, A. Heller, JACS, 2003, 125, 6588-6594.
[3] A. Chandrakasan, N. Verma, D.C. Daly, Annual Rev. Biomed. Eng., 2008, 10, 247-274.
(Invited) First-Principles Design of Mixed Proton-Electron Conductors for Solid-Oxide Fuel Cell Electrodes
Authors: Pavone Michele 
Published: February 2020

Electrolyzer and fuel cells based on proton-conducting solid oxides (PC-SOEC/FC) are gaining ground in the energy conversion scenario, thanks to fast proton diffusion rates at convenient operating temperatures. However, current performances are curbed by severe limitations of common electrodes [1]. Within this context, here we outline the latest work of our group on the rational design of innovative electrode materials for PC-SOEC/FC applications. With first-principles methods we aimed at providing unbiased explanations and predictions of materials properties and functions, so to assess new design principles based on quantum mechanics.
The desired electrode materials for PC-SOEC/FCs should pair mixed proton/electron conductive (MPEC) features to good catalytic activity. We followed two design strategies: induction of proton conduction to mixed ion-electron conductors to obtain triple conducting oxides [2] or induction of electronic conduction on well-known proton conductor materials [3]. To this end, in bulk solids we evaluated oxygen vacancy formation and water uptake enthalpies, and we characterized the minimum-energy path for proton migration and the corresponding barrier heights. Then, we investigated the catalysis associated to the four proton-coupled electron transfer processes for the oxygen evolution reaction (OER) and reverse oxygen reduction reaction (ORR) at the electrode surfaces. Our calculations revealed the structural and electronic features than are needed for an effective bifunctionality towards the OER and ORR.
Our findings can trigger the targeted experimental synthesis and testing of new single-phase electrodes and can enable the deployment of reversible proton-conducting SOEC/FC devices. Moreover, our analysis can be exploited for the rational design of bifunctional electrocatalytic systems with similar key characteristics.
[1] L. Bi, S. Boulfrad, and E. Traversa, Chem. Soc. Rev. 43 (2014) 8255.
[2] A. B. Muñoz-García and M. Pavone, Chem. Mater. 28 (2016) 490
[3] A. B. Muñoz-García, M. Tuccillo, and M. Pavone, J. Mater. Chem. A 5 (2017) 11825
The Ionic and Water Transport Properties Studies of Univalent Ion Exchanged Perfluorosulfonate Membrane
Authors: Peng Jing , Goenaga Gabriel A. , Zawodzinski Thomas A 
Published: February 2020

Perfluorosulfonic acid (PFSA) polymer membranes have been widely studied in the context of their applications as ion exchange medium/solid electrolytes in proton exchange membrane (PEM) fuel cells and other redox applications since 1970s(1). Water management plays a significant role in the performance of polymer membrane electrolytes, especially in fuel cells, because the ionic conductance dramatically decreases at low relative humidity, while excess water may flood the flow channels and hinder the transport of reagents such as gases (2). The conductivity and water diffusion coefficient of membranes therefore are always of concern because of their function in electrochemical devices.
In this work, Li+, Na+, NH4
+ and TEA+ form PFSA membranes were prepared based on H-form 3M PFSA membrane. The water uptake, density and conductivity of these membranes were investigated at various hydration levels. It’s found that the hydrophilicity of cations determines the water uptake of membranes with different cations, showing a series of water uptake in the order of: H+ > Li+ > Na+ > NH4
+ > TEA+. As expected, H+ form membranes show the highest conductivity among all membrane forms due to the smallest charge carrier size and proton hopping transport mechanism. This mechanism may also contribute for NH4
+ transport, resulting in a comparably high conductivity of NH4
+ form membranes even though the latter take up much less water. Pulsed field gradient (PFG) Nuclear Magnetic Resonance (NMR) was exploited to observe the diffusion coefficient of water in the membranes. It was observed that hydrophilicity of cations and the hydrogen bonding interactions affect the water transport in the membranes. Based on density measurements, a partial molar volume analysis is carried out in this study. This parameter provides insight into the water and polymer interactions in various univalent PFSA membranes.
Acknowledgement.
We gretefully acknowledge the support of this work by the Office of Naval Research. We also appreciate the assistance of 3M company in providing 3M PFSA membrane samples.

References:

K. A. Mauritz and R. B. Moore, Chemical Reviews, 104, 4535 (2004).

T. A. Zawodzinski, C. Derouin, S. Radzinski, R. J. Sherman, V. T. Smith, T. E. Springer and S. Gottesfeld, J Electrochem Soc, 140, 1041 (1993).

Figure 1
Biomass Activated Carbon for Solid Supercapacitors
Authors: Lian Keryn , Genovese Matthew , Wu Haoran , Virya Alvin , Li Jak 
Published: February 2020

Biomass activated carbon (AC), produced from the pyrolysis of biomass waste feedstock (wood, agricultural residues, etc.) has been studied as low cost Electrochemical Double Layer Capacitor (EDLC) electrodes. Their parent biomass materials also lead biomass ACs with different natural porous templates which can be further tuned or modified via chemical activation techniques. We have investigated several waste biomass ACs ranging from corn cobs, pine cones, to chitosan and found that, while all inherited porous structures from nature, they displayed quite different surface chemical compositions and pore structures. For example, the surfaces area of these biomass AC were in around 570 m2/g, 2400 m2/g and 3300 m2/g, respectively. These differences, especially in surface area, morphology and pore size distribution, have direct impact on the electrochemical performance of these biomass ACs in both liquid and solid electrolytes. Among the three biomass materials, chitosan-based carbon has demonstrated a high level of hierarchical meso-pore structure and the highest specific energy density.
Solid-state supercapacitors, enabled by polymer electrolytes, are ideal solutions for future energy storage applications that require high performance, safe operation, light-weight, thin and flexible form factors. We have developed a series of aqueous-based polymer electrolytes that are proton-conducting, hydroxide ion-conducting or neutral salt ion-conducting to match various cell chemistries. Many electrolytes exhibited ionic conductivities >10-2mS/cm and maintained stable performance under ambient conditions (i.e. room temperature and 45% relative humidity).
In this talk, we will present the development of solid EDLC devices leveraging biomass ACs and aqueous based polymer electrolytes. The performance of solid EDLC devices using chitosan AC carbon and polymer electrolyte containing Li2SO4 will be compared with their liquid counterpart (Fig. 1) as well as with the commercial baselines.

Figure 1