bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Two-Dimensional Layers: The Synthesis and Properties of Graphene and Beyond
Authors: Robinson Joshua A 
Published: February 2020

The isolation of graphene constituted a new paradigm in next generation electronic technologies. In this work, I will discuss recent works in graphene and beyond for novel device applications. This includes a focus on epitaxial graphene materials and device properties, as well as “beyond graphene” opportunities that could lead to new areas of research. Transition metal dichalcogenides (TMDs) and their heterostructures could have an even greater impact on next generation technologies. Molybdenum disulfide (MoS2) is currently a leading TMD for scientific exploration, but there are a variety of other suitable, less explored, TMDs and heterostructures that exhibit very attractive bandgaps, charge carrier effective masses, and mobilities for electronic applications. Transition-metal dichalcogenides (TMDs) in the form of MeX2 (where Me = a transition metal such as Mo, W, Ti, Nb, etc. and X = S, Se, or Te) also exhibit extreme flexibility, possession of tunable band gaps, modest electron mobilities, and wide variety of band-offsets. Additionally, monochalcogenides (i.e. GaSe) have the potential to provide routes toward alternative wide bandgap 2D materials suitable for high power and UV optoelectronics. Furthermore, synthesizing and heterogeneously combining these atomic layered materials to form van der Waals (vdW) solids, where each layer may be different from the previous, is a powerful way to develop novel nanoscale materials. This talk will elaborate on recent breakthroughs for direct growth of two-dimensional atomic heterostructures (MoS2, WSe2, and hBN) on a graphene template, discuss recent breakthroughs in the synthesis of 2D nitrides beyond hBN, and elucidate mechanisms for achieving selective area growth of 2D materials.
Use of Patterned Metal Anodes for Studying Hydrogen Electrochemical Oxidation Reaction in Proton-Conducting SOFCs
Authors: Sun Shichen , Awadallah Osama , Cheng Zhe 
Published: February 2020

Despite the great potential for proton-conducting solid oxide fuel cells (SOFCs) for clean power generation at intermediate temperature (e.g., 400-700 oC), there are significant knowledge gaps about fundamental aspects for such cells. In particular, very little is known about the kinetics and reaction mechanism for the hydrogen electrochemical oxidation reaction in proton-conducting SOFCs. Here, we will report the preliminary results of our study using patterned metal anode over acceptor-doped Ba(Ce,Zr)O3 proton-conducting electrolyte. The effects of various factors such as choice of anode metal (e.g., nickel versus copper), anodic bias voltage, gas atmosphere, temperature, and electrode geometry (e.g., triple phase boundary TPB length and electrode area) on the electrochemical behaviors of proton-conducting SOFC will be studied. The results will be correlated to previous studies for hydrogen electrode reaction in conventional oxide-ion conducting SOFCs, and the implications on the fundamental reaction mechanism for the hydrogen electrode reaction involving proton-conducting oxides will be discussed.
Transition Metal Chalcogenide Based Elelctrocatalysts for Facile Water Oxidation/Reduction
Authors: Swesi Abdurazag T , Masud Jahangir , Nath Manashi 
Published: February 2020

Transition metal chalcogenides has been a heartthrob of solid state chemists owing to the richness of properties they exhibit as well as their structure-property correlation. In addition to their viable optoelectronic properties, it has been recently observed that some of these transition metal chalcogenide (especially selenides) show high electrocatalytic activities for oxygen evolution/reduction reactions (OER/ORR respectively) and hydrogen evolution reaction (HER). Recently we have formulated some new transition metal chalcogenide based compositions which show an enhanced catalytic activity for OER based on their d-electron occupancy and structural parameters.1 Among these the Ni-based selenide thin films and nanostructures show much better catalyst activity along with lower onset potential for O2 evolution outperforming the state-of-the-art precious metal based catalysts. It was also observed that doping other transitional metals in the Nickel selenide matrix led to enhancing catalyst efficiency. The catalysts were synthesized mainly through electrodeposition on different substrates like Au-coated glass, Au-coated Si as well as glassy carbon (GC). The nanostructured catalysts were made through chemical vapor deposition (CVD) and solvothermal reaction. In a separate approach nanorod and nanotube arrays of these electrocatalysts were grown through electrodeposition on lithographically patterned nanoelectrodes. Nanostructuring typically led to much better efficiency with low catalyst volume, with the nanorod/nanotube pattern producing the highest activity with lowest electrode coverage with the active material. The catalytic activities for OER, ORR and HER were investigated through detailed electrochemical measurements including linear scale voltammetry, chronoamperometry, Tafel slope analysis as well as determination of Faradaic efficiency through rotating ring disk electrode studies. Interestingly some of these selenides showed bifunctional or trifunctional nature showing efficient catalytic activity for OER-HER and OER-HER-ORR processes, respectively. In this talk we will present a systematic study of the selenide based electrocatalysts including binary (NixSey, CoxSey) as well as ternary chalcogenides, Ni
xMy
Sen (M = Fe, Co, Mn, Al) and investigating their catalytic activities for OER, HER, and ORR reactions. We will also discuss the effect of d-electron counts, electronic structure and morphology on the catalytic efficiency.
References
Swesi, A.; Masud, J.; Nath, M. Energy Environ. Sci.
2015 doi: 10.1039/C5EE02463C.
Structure-Activity Relationships in Ni-Fe Oxyhydroxide Oxygen Evolution Electrocatalysts
Authors: Batchellor Adam S. , Burke Michaela S. , Enman Lisa J. , Boettcher Shannon Wachter 
Published: February 2020

The oxygen evolution reaction (OER) is kinetically slow and hence a significant efficiency loss in electricity-driven water electrolysis. Understanding the relationships between architecture, composition, and activity in high-performing catalyst systems are critical for the development of better catalysts.1

To reach the relevant operating conditions of industrial electrolyzers, high mass loadings are required even when current state of the art catalysts are employed. Several challenges arise when studying high loading films which complicate determination of intrinsic OER activity. For example, to accurately report turnover frequencies the number of metal centers participating in the OER must be known. Furthermore, diminished electronic and mass transport through a thick catalyst film could result in active sites located in different parts of the film generating oxygen at different rates. We compare several methods of determining the number of electrochemically active metal centers, and report the loading dependent behavior of Ni-Fe oxyhydroxide films, the fastest known water oxidation catalyst in alkaline media.2We find that commonly employed methods used to determine the electrochemically active surface area could result in errors of several orders of magnitude due to the potential dependent conductivity of many transition metal-based catalyst systems.
We discovered that the method of electrodeposition strongly affects the intrinsic Ni(Fe)OOH activity, as well as the practical electrode performance.3Pulse electrodeposited films increase in turnover frequency with loading, while continuously deposited films decrease in activity with loading. The improvements stemming from this pulsed deposition method are wide reaching, affecting both the architecture and the composition of the catalyst film. The role of these effects on intrinsic and geometric OER activities will be discussed in the context of the design principles for high-performance electrode architectures.
(1) Burke, M. S.; Enman, L. J.; Batchellor, A. S.; Zou, S.; Boettcher, S. W. Oxygen Evolution Reaction Electrocatalysis on Transition Metal Oxides and (Oxy)hydroxides: Activity Trends and Design Principles. Chem. Mater.
2015, 27, 7549-7558.
(2) Trotochaud, L.; Ranney, J. K.; Williams, K. N.; Boettcher, S. W. Solution-Cast Metal Oxide Thin Film Electrocatalysts for Oxygen Evolution. J. Am. Chem. Soc.
2012, 134, 17253-17261.
(3) Batchellor, A. S.; Boettcher, S. W. Pulse-Electrodeposited Ni–Fe (Oxy)hydroxide Oxygen Evolution Electrocatalysts with High Geometric and Intrinsic Activities at Large Mass Loadings. ACS Catalysis
2015, 5, 6680-6689.
Hydrogen Production Using Different Graphene/Au@TiO2 Composites Under Visible and Ultraviolet Light
Authors: Machín Abniel , Márquez Francisco 
Published: February 2020

In order to avoid serious environmental and economic damages from energy use, humans must stop using fossil fuels altogether, as soon as possible. One possible strategy to cut the dependence of fossil fuels and, at the same time create a new economic force, is to develop a hydrogen based energy economy. A potentially viable way forward is to produce H2 from water by combining solar energy and heterogeneous photocatalysts. For these reasons the objectives of this investigation were: 1) synthesize a high surface area TiO2 nanowires (NWs) catalyst in the rutile phase, 2) incorporate different amount of gold nanoparticles into the as-synthesized catalyst and into the commercial form of TiO2 (P-25) using a chemical reduction method, 3) incorporate graphene to the Au@TiO2 composites, 4) produce hydrogen via water splitting using visible and ultraviolet light. The hypotheses of the study were: a) The catalyst with the higher surface area will produce the highest amount of hydrogen, b) The gold nanoparticles will enhance the hydrogen production and will allow the use of visible light due to the surface plasmon resonance of the gold nanoparticles, c) The incorporation of graphene will enhance the hydrogen production since it will reduce the electron/hole recombination in all the Au@TiO2 composites. Interestingly, the incorporation of gold nanoparticles into the titania surface enhanced the surface area in both P25 and TiO2 NWs. The hydrogen production obtained by using Au@P25 catalysts was measured to be 800 μmolg-1h-1 under irradiation at 400 nm and 1,436 μmolg-1h-1 using Au@TiO2 NWs at the same wavelength. The incorporation of graphene enhanced the hydrogen production in both P25 and TiO2 NWs. A maximum hydrogen production of 978 μmolg-1h-1 and 1,689 μmolg-1h-1 was obtained for P25 and TiO2 NWs, respectively, after the incorporation of graphene. All the hypotheses were correct and all the objectives achieved. The characterization of the synthetized compounds were performed with: 1) X-ray diffraction (XRD), 2) Field emission Scanning Electron Microscopy (FESEM), 3) Brunauer, Emmett and Teller (BET), 4) Gas Chromatographer with a Thermal Conductive detector (GC-TCD) and 5) Ultra Violet Visible spectroscopy (UV-VIS). Future works will be focused on producing hydrogen via water splitting by incorporating gold nanoparticles and graphene on synthesized zinc oxide nanowires and nanoparticles. The results with the zinc oxide composites will be compared with those obtained by the TiO2 composites. The contribution of this investigation relies in finding new and clean ways to produce hydrogen via water splitting.
Abrupt Mechanistic Variation of Hydrogen Evolution Reaction on Metal Electrode Surfaces in the Potential-pH Space
Authors: Haghighat Shima , Dawlaty Jahan 
Published: February 2020

Understanding the mechanisms of multi-electron and multi-proton electrochemical reactions, particularly in the context of renewable electrochemical energy conversion, is an outstanding challenge. The electrocatalytic hydrogen evolution (2H+ + 2e-...> H2) is the half reaction of water splitting and is heavily studied. However, the kinetic variation of this reaction under various pH conditions has not been fully understood.
In this work, we studied hydrogen evolution reaction on different electrodes (Pt, Cu, FeS2, Ni, and Ti) over a wide range of neutral (pH=6.5) to acidic (pH=1.5) solutions. Despite variations in the properties of these electrodes, we observe a discontinuous change in the onset potential as a function of current in the pH range of 2.5 to 3.5 in all the electrodes. We also represent two fundamental kinetic parameters, empirical electron transfer coefficient α and the reaction order with respect to proton ρ, as a function of pH and potential. An important observation is that α is constant (α≈0.2) at pH values higher than the discontinuous jump, while at lower pH values alpha increases with decreasing pH. The maximum value of alpha varies for different electrodes and is increasing from Ti < Ni< Cu < FeS2 < Pt. The proton reaction order is non-zero in the acidic side, whereas it is zero in the neutral limit and this trend is common for all the electrodes.
To our knowledge, for the first time, we are presenting the kinetic parameters in two-dimensional plots as a function of both pH and potential. This representation allows us to clearly see global trends in the kinetics of the reaction. We will propose possible explanations for such common behavior based on a kinetic model that accounts for both concerted and step-wise electron and proton transfer. We hope that this study sheds light on the fundamentals of electron-proton transfer during hydrogen evolution.

Figure 1
Hematite Nanostructures for High Efficient Solar Water Splitting
Authors: Sun Xuhui , Deng Jiujun , Zhong Jun 
Published: February 2020

Hematite has emerged as a good photocatalyst for efficient solar water splitting due to its favorable optical band gap (2.1–2.2 eV), extraordinary chemical stability in oxidative environment, abundance, and low cost. According to theoretical prediction, the solar-to-hydrogen efficiency of hematite can be 16.8% and the water splitting photocurrent can be 12.6 mA cm-2. However, the practical performance of hematite for solar water splitting is far from the ideal case which has been limited by several factors such as poor conductivity, short lifetime of the excited-state carrier (10-12s), poor oxygen evolution reaction (OER) kinetics, short hole diffusion length (2–4 nm), and improper band position for unassisted water splitting. In our recent work, enormous efforts have been focused on improving the performance of hematite nanostructure photoelectrode. Different methods such as morphology control, elemental doping, and improvement of the charge transport of hematite have been developed to improve the performance of hematite photoelectrode in solar water splitting. We present the preparation of Ti-doped and H2-treated hematite nanostructures. The H2-treated hematite photoelectrode showed a high photocurrent of 2.28 mA/cm2 at 1.23 V vs. RHE, which was over 2.5 times than that for pristine hematite. Moreover, when compared to hematite photoelectrode with oxygen vacancies but treated by controlling the oxygen content in the sintering process, a cathodic shift of the onset potential was observed by about 120 mV (from 0.99 to 0.87 V vs. RHE). The cathodic shift of the onset potential was attributed to the surface effect of H2-treatment. The Ti-doped hematite nanostructures with optimized oxygen vacancies achieved a remarkable maximum photocurrent value of of 4.56 mA/cm2at 1.6 V vs. RHE. Moreover, Ti-doping can expand the applicative partial oxygen pressure to a wide range compared to that for undoped hematite. The expansion of partial oxygen pressure range might be useful for the practical application. The coupling of extrinsic Ti-doping and intrinsic oxygen vacancies stands for an effective strategy to design oxide-based photoanodes for efficient solar water oxidation.

Reference:

J. Deng, X. Lv, J. Liu, H. Zhang, K. Nie, C. Hong, J. Wang, X. H. Sun, J. Zhong, S. T. Lee, ACS Nano, 9, 5348 (2015).

M. Li, J. J. Deng, A. W. Pu, P. P. Zhang, H. Zhang, J. Gao, Y. Y. Hao, J. Zhong and X. H. Sun, "Hydrogen-Treated Hematite Nanostructures with Low Onset Potential for Highly Efficient Solar Water Oxidation", Journal of Materials Chemistry A, 2, 6727 (2014)

A.W. Pu, J.J. Deng, M. Li, J. Gao, H. Zhang, Y.Y. Hao, J. Zhong and X.H. Sun, “Coupling Ti-doping and Oxygen Vacancies in Hematite Nanostructures for Solar Water Oxidation with High Efficiency”, Journal of Materials Chemistry A, 2, 2491(2013)

J.J. Deng, X.X. Lv, J. Gao, A.W. Pu, M. Li, X.H. Sun and J. Zhong “Facile synthesis of carbon-coated hematite nanostructures for solar water splitting”, Energy & Environmental Science, 6, 1965 (2013).
The ARPA-E CHARGES Program: How to Get Paid for Grid Storage, and the Duty Cycles Needed to Prove Your Technology
Authors: Albertus Paul S. , Heffner Reid R. 
Published: February 2020

The Advanced Research Projects Agency-Energy (ARPA-E) has invested a significant amount of funding in novel, electrochemical-based electrical energy storage technologies for stationary applications. However, widespread adoption of new storage technologies has been hindered by a lack of proven economic benefit, performance, and long term reliability. This presentation will focus on the economic modeling of the value of grid energy storage conducted in the Cycling Hardware to Analyze and Ready Grid-Scale Electricity Storage (CHARGES) program, including the revenue that can be captured under both existing and potential future utility rate structures and markets for applications such as day ahead, real time, demand charge reduction, ancillary services, and others. In addition to the revenue that can be captured by participation in single applications, the revenue available by stacking applications will also be assessed. The CHARGES program has also sought to translate the operation of a battery to maximize revenue into duty cycles that researchers can run on the electrochemical technologies they are developing, to move beyond the typical constant-current cycling to duty cycles linked to economic valuation in an actual grid context. At the end of this presentation, battery developers should have a clear understanding of value-driven performance requirements that allow for evaluation of their technology early in the development cycle.
Determination of Mass and Charge Transport of La2Ni0.95Al0.05O4.025+
d
at Isothermal Condition
Authors: Im Ha-Ni , Jeon Sang-Yun , Yoo Young-Sung , Song Sun-Ju 
Published: February 2020

Mixed oxide-ion and electron conducting ceramic material La2NiO4+
d (LNO) have been reported to exhibit impressive oxide ion and p-type electronic conductivity, and high catalytic activity which makes them an excellent component of some electrochemical devices such as fuel cell cathode, oxygen permeation membrane and sensors. The structure of hyper-stoichiometric LNO is consists of alternating LaNiO3 perovskite and LaO rock salt layers. The oxygen excess in LNO is associated with the incorporation of interstitial oxygen into the rock salt layers and holes are simultaneously created in the perovskite layers to maintain the charge neutrality of the system. Given the oxygen activity difference across an oxide, its electrochemistry is determined by its ambipolar conductivity or the product of its oxide ionic conductivity and electronic transference number or vice versa. The partial ionic and electronic conductivities which govern the mass transport in an electric field are thus the most important properties of an electrochemical device material to characterize and understand. However, there are very few reports on the study of transport properties of mixed conducting oxide material. In this work we have analyzed the partial conductivity of La2Ni0.95Al0.05O4.025+
d
in relation with the thermoelectric power and calculate diffusion coefficient and surface exchange coefficient in order to analyze the oxygen exchange kinetics of La2Ni0.95Al0.05O4.025+
d.
Evaluation and Comparison of the Electric Field in the Physicochemical Properties of a Vertisol Type Soil and Sodium Bentonite
Authors: Pérez Maribel , Rodríguez José Miguel , Gómez César , Bustos Erika 
Published: February 2020

Soil electro-remediation is a technique that allows the removal of organic and inorganic compounds [1-4]. Changes in the soil matrix during application of the electric field affects desorption and/or absorption, and even the mobilization process of pollutants [5].
Changes caused by the potential gradient in a model soil (sodium bentonite) and the results of pH and contaminant transport of a model designed in Visual Basic were compared to evaluate the process of electro-migration which was simulated through the transport number.
When we compared the behavior of the model soil with a Vertisol soil, the parameters evaluated throughout the cell were: pH, electrical conductivity and z potential. The behavior between the model soil and the Versitol type soil pH is similar in the area near the anode where there is a decrease in pH attributed to the generation of H+ and the cathode pH was slightly increased by the presence of –OH (Figure 1).
However, the behaviors of the electrical conductivity and z potential are not similar due to the presence of organic matter, microorganisms and the diversity of ions contained in the Versitol type soil. The observed changes in these parameters promote the removal of pollutants. In the case of Vertisol type soil the observed changes in the soil matrix are minimal, which is an advantage of electro-remediation in comparison of another treatments of soil, as biological and chemical procedures.

References.

[1] K. R. Reddy, Technical challenges to in-situ remediation of polluted sites. Geotech. Geol. Eng., 28(3), 211-221 (2010).
[2] M. Pérez-Corona, A. Corona, E. D. Beltrán, J. Cárdenas and E. Bustos, Evaluation of IrO2 – Ta2O5|Ti electrodes during the electroremediation of hydrocarbon – contaminated soil. Sustain. Environ. Res., 23 (4), 279 – 284 (2013).
[3] A. Medel, D. Patiño, E. Méndez, Y. Meas, L. Godínez, J. Manríquez, F. Rodríguez, A. Rodríguez and E. Bustos, Novel electrokinetic remediation system – boron doped diamond (EKR-BDD) process for the destruction of polyaromatic hydrocarbons (PAHs) in liquid phase. Environ. Engin. Manag. J., 14 (4) 879 – 886 (2015).
[4] I. Robles, M. J. Lozano, S. Solís, G. Hernández, M. V. Paz, M. G. Olvera and E. Bustos, Electrokinetic treatment of mercury – polluted soil facilitated by ethylenediaminetetraacetic acid coupled with a reactor with a permeable reactive barrier of iron to recover mercury (II) from wáter. Electrochimica Acta 181, 68 – 72 (2015).
[5] I. Robles, E. Bustos and J. Lakatos, Comparison of the sorption behavior of mercury (II) on inorganic, organic and biomass substrates in the presence of different counter-ions. Sustain. Environ. Res., 25 (5), 255- 260 (2015).

Figure 1