bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Microscopy Study of Structure and Defects in Li-Rich Layered Oxide
Authors: Shukla Alpesh Khushalchand , Ramasse Quentin , Darbal Amith , Das Partha Pratim , Mendoza Joan , Estrade Sonia , Ophus Colin , Duncan Hugues , Chen Guoying , Nicolopoulos Stavros , Yedra Lluis
Published: February 2020

Transformations in Li-rich layered oxides have been extensively studied recently for their potential application in Li-ion batteries. These materials have attracted a lot of interest due to the high capacity offered by them. However, the structure of these materials in their pristine state is not clearly understood. Several reports have assigned their structure to be trigonal (R-3m), monoclinic (c2/m), or a combination of both (composite). The present study discusses the structure of Li1.2(Ni0.13Mn0.54Co0.13) O2 prepared with two different morphologies: plates and needles, using the results obtained from aberration corrected (scanning) transmission electron microscopy, electron energy loss spectroscopy (EELS), convergent beam electron diffraction and precession electron diffraction tomography and question the validity of the the claims of them being “composite”. It was found that these materials consist of domains which correspond to variants of monoclinic structure. It will be shown how diffraction-based experiments on such materials can often lead to misleading conclusions, since analysis of diffraction-based techniques inevitably assign them as trigonal, although the present study shows that the three-fold symmetry observed in electron diffraction patterns result from the combination of the variants having monoclinic structure.

Furthermore, results from STEM and EELS experiments showed that the pristine materials have several defects consisting of differently ordered structure on their surface, and several Cobalt-rich line defects. These results prescribe that extreme care should be taken while interpreting the electron microscopy results obtained from cycled samples.
Bio-Electrochemical Treatment of Wastewater Organic Load: Comparison of Microbial Electrolysis, Microbial Fuel Cell and Microbial Electrochemical Snorkel Performances
Authors: Erable B , Blanchet E , Etcheverry L. , Desmond E , Bridier A , Bouchez T , Bergel A
Published: February 2020

The removal of the total organic load (COD) from urban wastewater was studied in different bio-electrochemical systems (BES): microbial electrolysis, microbial fuel cell (MFC), and microbial electrochemical snorkel (MES). Here is presented the concept of MES [1], a simplified design of a “short-circuited” MFC.

The MES cannot provide current but it is optimized for wastewater treatment. Technically, the MES concept can simply consist of a single piece of conductive material on which there are (i) one end colonised by an electro-active biofilm acting as a microbial anode (anaerobic zone), and (ii) one end covered with oxygen (bio- or not) electro-catalyst that ensures electron removal to the final electron acceptor and allows bacteria “snorkelling” to oxygen. Unlike MFCs, a MES does not divert energy to produce electricity but it ensures maximum efficiency for the oxidation of organic matter.

COD removal comparison with the different BES was made starting from optimized graphite based microbial anodes already working at steady state rate of oxidation. Optimization of microbial anodes consisted of immersing a microbial anode already colonized with electoactive microorganisms together with a second polarized clean electrode resulting in the formation of an electroactive biofilm on the clean electrode that became more effective than the initial one. This strategy multiplied the current provided by the second electrode by a factor ranging from 2 to 20 in respect to the initial one. Comparative analysis of microbial diversity on electrodes was performed by pyrosequencing technology. Then, the comparative study using microbial anodes in different BES for the treatment of urban wastewater validated the MES concept since the MES process ensured about 75% of wastewater COD removal in less than 24 hours as well as a “short-circuited” MFC.

In conclusion, the MES technology, which aims at maximizing the reaction rates by elimination of current generation, provided degradation performance far higher than the MFCs that operated at optimum power. This demonstration opens a new route for the design of extremely simple electro-microbial devices for wastewater treatment.

[1] B. Erable et al., 2011. Biofouling 27(3):319-326. doi: 10.1080/08927014.2011.564615.
Engineered, Modular Microbial Communities for Simultaneous Wastewater Decontamination and Energy Generation
Authors: Ista Linnea K , Atanassov Plamen , Hanson David T , El-Naggar Mohamed
Published: February 2020

We propose a strategy to produce biocatalytic wastewater cleaning materials that incorporate microorganisms simultaneously removing organic and inorganic contaminants while creating electricity (or hydrocarbon fuel) for energy generation in support of a sustainable and portable system.

Central to our work will be then encapsulation of dissimilatory metal reducing bacteria for energy generation on the anode of a microbial biofuel cell (MFC) . We have previously demonstrated both great stability and greater current densities produced Shewanella oneidensis when biofilms of this organism are immobilized on a carbon anode. 1While our published results indicate full operation for a week, one such device was active for a full 6 months in our laboratories, indicating the stability and functionality of such systems.

While DMRBs are able to remove a plethora of organic compounds, including pesticides, inorganic compounds, such as ammonia, phosphate and heavy metals must also be removed to produce clean water. Immobilized algae have recently been shown to effectively remove phosphorous and nitrogen from wastewater. 2 An advantage of an encapsulated system is demonstrated by the immunity of this system to population fluctuation, the presence of other solids, or competing bacteria that frequently plague phosphate removal in particular.3 Such a system could be combined with, for example, Shewanella oneidensis in a second module and Geobacter sp. in a third, and used to produce a self-regererating carbon neutral electrical system.

Alternatively, the Geobacter module could be replaced by a module containing an acetate/methanogen syntrophic community to generate methane.

Other example modules include algae to remove heavy metals 4, Acinetobacter venetianus to remove oil spills 5, or pesticide remediating heterotrophs 6.

Research areas for this program will include metabolic activity of constituent organisms upon encapsulation, optimization of the transport characteristics of the encapsulating silica and the integration of electrodes or other energy collection modalities.

(1) Luckarift, H., Sizemore, S., Roy, J., Lau, C., Gupta, G., Atanassov, P., Johnson, G. Chem.Comm.
2010, 46, 6048.

(2) Shi, J.; Padola, B.; Melkonian, M. Bioresource Tech
2014
154, 260.

(3) Tu, Y.; Schuler, A. J. Environ Sci Technol
2013, 47, 3816.

(4) Montiero, C. M.; Castro, P. M. L.; Makcata, F. X. Biotechnol Prog
2012, 28, 299.

(5) Luckarift, H. R.; Sizemore, S. R.; Farrington, K. E.; Fulmer, P. A.; Biffinger, J. C.; Nadeau, L. J.; Johnson, G. R. Biotechnol Prog
2011, 27, 1580.

(6) Nunez, O. C.; Lopes, A. R.; Manaia, C. M. Appl Microbiol Biotechnol
2013, 97, 10275.
Growth and Features of TiO2 Nanotubes Surfaces on Industrial Titanium by Anodizing in Organic Medium
Authors: Zamudio-Torres Ildefonso , Perez-Bueno José Jesús , Meas-Vong Yunny
Published: February 2020

This work shows the growth of TiO2 nanotube by anodizing of surfaces metallic titanium and its features as surface. The material used was titanium industrial plates (99 %). The baths were constituted by 98% v/v of ethylene glycol, 2.5 ppm of O2 (water as a source), 1,700 ppm of F-, and a pH of 6.6. The concentrations of O2 were oscillating between 2.3 and 1.9 ppm, and the conductivities in the cell were about 480 μS/cm. The potential was set using a ramp of 6 V/min and a final value of 60 V for 2 h. Along the experiment, constant dripping of water was used.

In a first step, a layer of early oxide was formed. Then, anions migrate through the oxide layer to the Ti/TiO2 interface and reacted with Ti as shown in reaction (1) and (2). Meantime, the applied electric field ejects Ti4+ cations from the Ti/TiO2 interface and made that Ti4+ move towards the TiO2/electrolyte interface. The chemical dissolution occurred at the interface of TiO2/electrolyte, where TiO2 was dissolved by F− with the help of H+ and the field assisted dissolution occurs at the Ti/TiO2 interface as indicated by reactions (3) and (4) [1].

2H2O → O2+ 4e− + 4H+

(1)

Ti + O2→ TiO2

(2)

TiO2+ 6F− + 4H+ → [TiF6]2− + 2H2O
(3)

Ti4+ + 6F−→ [TiF6]2−

(4)

These surfaces showed to be superhydrophilic. Studies about its surface energy, and corrosion resistance were realized, the roughness factor was determined by optical profilometer and cyclic voltammetry. The electroactive surface areas were determined by this technique too.

[1] T. Xu, J. Lin, J. Chen, and X. Chen, “The effect of pre-pattern on the morphology and growth speed of TiO2 nanotube,” Appl. Surf. Sci., vol. 258, no. 1, pp. 76–80, 2011.
Assessment of Cytocompatibility and Magnetic Properties of Nanostructured Silicon Loaded with Superparamagnetic Iron Oxide Nanoparticles
Authors: Granitzer Petra , Rumpf Klemens , Tian Yuan , Coffer Jeffery , Akkaraju Giri , Poelt Peter , Reissner Michael
Published: February 2020

The aim of this work is to create a biocompatible superparamagnetic nanocomposite applicable as vehicle for magnetically guided drug delivery. Therefore Fe3O4-nanoparticles have been infiltrated or chemically grown within nanostructured silicon. Both materials, the nanostructured silicon as well as the iron oxide nanoparticles, offer low toxicity and investigations concerning the cell-viability have been carried out. The magnetic properties of the system have been optimized concerning the blocking temperature TB and the magnetic moment M which means that TB has to be far below room temperature and M should be as high as possible, whereas these both properties are counteracting. TB indicates the transition between superparamagnetic behavior and blocked state of the composite. Due to the fact that TB is not only dependent on the particle size (diameters between 4 and 10 nm have been investigated) but also on the magnetic interactions between the particles there are two main routes to fabricate such a composite with desired TB - first a modification of the pore-loading with a concomitant variation of the distance between the particles within one pore and second a variation of the porous silicon morphology influencing the distance between particles within adjacent pores. To ensure that there is no remanence after the external field has been switched off, magnetic coupling between the particles has to be kept sufficiently low. A particle-size/distance and template dependent assessment of the magnetic properties and the cytotoxicity of the nanocomposite will be presented. Furthermore the differences between infiltrated Fe3O4-nanoparticles and chemically grown particles inside the pores will be figured out.
NiO-SDC Mixed Ionic Electronic Conducting Anode for Low Temperature Thin Film SOFCs
Authors: Cho Gu Young , Cha Suk Won , Lee Yoon Ho , Park Taehyun , Noh Seungtak
Published: February 2020

Solid oxide fuel cells (SOFCs) are promising candidates for next generation energy conversion devices due to its fuel flexibility, high efficiency, high energy density, and no CO poisoning. However, high operation temperature which is required due to poor ionic conductivity of oxide electrolyte of typical SOFCs disturbs the commercialization.

Various thin film techniques for fabrication of electrodes and electrolyte are applied to lower the operation temperature of SOFCs. Pulsed laser deposition (PLD), sputter, chemical vapor deposition (CVD), and atomic layer deposition (ALD) are used to prepare thin film electrodes or electrolyte.

Typical low temperature SOFCs use platinum (Pt) as an electrode material due to high electrical conductivity and superior catalytic activity of Pt for both hydrogen oxidation reactions and oxygen reduction reactions. Despite of these strong points, high cost, thermal degradation due to agglomeration, mismatch of thermal expansion coefficient and limited triple phase boundaries (TPB) are still remained.

Mixed ionic electronic conducting (MIEC) anode materials such as NiO-YSZ, NiO-GDC, and NiO-SDC are usually used at typcial SOFCs due to high density of triple phase boundaries. These MIEC materials can relieve the thermal degradation and thermal stress. Cost is also reduced compared with Pt. Therefore, we applied the MIEC anode for low temperature thin film SOFCs.

In this study, we prepared anodic alumina oxide (AAO) based low temperature thin film SOFCs. NiO-SDC anode was fabricated via radio frequency sputtering method using NiO-SDC oxide target. The reactive RF sputtering process is conducted to prepare yttria-stabilized zirconia (YSZ) electrolyte on a NiO-SDC anode by using Y-Zr alloy target and Ar-O2 mixing gas. After electrolyte deposition, porous Pt cathode was deposited on the electrolyte by direct current sputtering method. Open circuit voltage (OCV), performance, and electrochemical impedance spectroscopy (EIS) were measured at 500C.
Development of Bicontinuous Carbon Foam/ Metal Sulfide Composites As Free-Standing Electrodes for Lithium Ion Storage
Authors: Ma Yue , Asfaw Habtom Desta , Edstrom Kristina
Published: February 2020

We designed and fabricated a series of bicontinuous carbon foam/metal sulfide composite with hierarchical porosities as a high performance free-standing anode electrode for lithium ion batteries. The synthetic method involves the scalable nanocasting process of layered structured MxS (M=Fe, Sn, Cu) using the high internal phase emulsion polymer (polyHIPE) as the structural support as well as the electronic conducting network. The as-developed C/MxS SnO2 electrode is highlighted by several innovative design concepts: firstly, macroporous carbon foam derived from the pyrolysis of polyHIPE could serve as the structural support as well as the sulfur source for the MxS synthesis; secondly, the C/ MxS bicontinuous network not only provides facile electronic transport and electrolyte percolation, but remove the necessity of usage of binder, carbon additive and massy metal current collector; thirdly, the off-stoichiometric zero valent metal particles is designed to provide the dual functionalities of electrically wiring the electroactive materials as well as the catalytic effect for graphitization of carbon. The electrochemical measurements of these C/ MxS electrodes were therefore conducted to demonstrate the high specific capacity (500 ~ 700 mA h g-1) and excellent rate capability up to 4 A g-1, which presents the best cycling performance among metal sulfide-based free-standing electrodes to date (C/FeS) and thus the superior structural design of electrodes. Finally, the storage mechanism of metal sulfides was investigated through the in-situ characterization techniques and Mössbauer spectroscopy.
Operando Electron Magnetic Measurements in Li-Ion Batteries
Authors: Gershinsky Gregory , Monconduit Laure , Zitoun David
Published: February 2020

One of the challenges in the development of batteries consists in the investigation of new electrode materials and comprehension of the mechanism of lithium uptake. Herein, we report on the first in operando measurements of electron magnetism on a battery during cycling. We have succeeded in designing a non magnetic cell and have investigated the lithiation mechanism of FeSb2, a high energy density anode material. The stepwise increase of the magnetic moment reveals an increase of amorphous Fe nanoparticle size, while Sb undergoes a reversible alloying with Li.1

In operando electron magnetism brings macroscopic and quantitative data on the amorphous Fe nanostructures formed during cycling. The investigation of real time characterization techniques enables the collection of information at the nanoscale, required to elucidate electrochemical mechanism. Since most of the electrode materials are based on 3d transition metals with high electron magnetic moment, we believe in-situ electron magnetic measurements will bring valuable information on conversion or alloying mechanism to forecast more efficient electrodes.

[1] G. Gershinsky, E. Bar, L. Monconduit, D. Zitoun Energy and Environmental Sciences
2014, C4EE00490F
Dependence of the Lithiation/Delithiation Potentials of Silicon Microwire Anodes on Their State of Charge and Sizes
Authors: Nöhren Sandra , Quiroga-González Enrique , Föll Helmut
Published: February 2020

Silicon microwires are a good alternative to graphite as active material in anodes for Li ion batteries. Besides a high gravimetric capacity of 4200 mAh/g, self-standing Si microwire anodes exhibit large cycle life (> 100) with a coulomb efficiency of 96 % without suffering of irreversible losses [1, 2]. It has been observed that for obtaining this exceptional performance it is necessary to charge the anodes within specific voltage limits depending on the dimensions of the Si microwires [1].

Four peaks have been found in voltammetry measurements which indicate that two lithiation and two delithiation events occur in the Li-Si system. In a previous study on Si mWs, a dependency of the lithiation and delithiation peaks during voltammetry studies on the dimensions of the Si microwires was observed [3]. In the present work the dependency of the lithiation/delithiation susceptibility of the anodes on their state of charge (SOC) has been studied. Si microwire anodes were charged to 0 %, 25%, 50 % and 75 % of their maximum capacity and analyzed by cyclic voltammetry. Single-crystalline Si wires with a lengths of 36, 46, 60, and 75 µm and widths of 1.2, 1.4, 1.6, and 1.8 µm were used for the study. For the test, paste electrodes composed of Si mWs, carbon black and CMC, coated on Cu foil were prepared. The current amplitude as well as the potential of the voltammetric peaks (lithiation/delithiation potentials) show a shift depending on the pre-lithiation levels. During the full-lithiation event, the current amplitude as well as the potential increase steadily when increasing the SOC, independently of the length of the wires (see Fig. 1a). The same effect is observed for wires of different thicknesses. The delithiation events are also affected by the SOC. They mainly decrease in potential when increasing the SOC, but at SOCs larger higher than 50 % the tendency is not so clear. According to the results, it can be inferred that the lithiation and delithiation are facilitated when increasing the SOC, probably until the pre-charge limit of 50 %.

[1] E. Quiroga-González, J. Carstensen, H. Föll, Electrochim. Acta, 101 (2013) 93.

[2] E. Quiroga-González, J. Carstensen, H. Föll, Materials, 6 (2013) 626.

[3] S. Nöhren, E. Quiroga-González, H. Föll, Size dependency study of Si mircowire anodes by cyclic voltammetry,

Kraftwerk Batterie 2013, Feb. 25-26, 2013, Aachen, Germany.
Invited Talk: Development of Nonaqueous Redox Flow Battery Technologies
Authors: Wang Wei , Vijayakumar Murugesan , Wei Xiaoliang , Cosimbescu Lelia , Xu Wu , Liu Tianbiao , Sprenkle Vincent
Published: February 2020

Nonaqueous redox flow batteries are generally considered to have higher energy densities than their aqueous counterparts because of their wider voltage windows. However, their performance has lagged far behind their inherent capability due to the combined limitations of redox chemistry, solubility of redox species, and cell design. Here we report a high-performance nonaqueous lithium–organic redox flow battery with a structure-modified ferrocene cathode. The ionic-liquid derivatization of ferrocene increases the solubility by more than 20 times in the supporting electrolyte (0.85 M as opposed to 0.04 M for pristine ferrocene). This improvement is confirmed by solvation chemistry studies through nuclear magnetic resonance analysis and density functional theory calculation. When coupled with a lithium-graphite hybrid anode, the flow battery exhibits a cell voltage of 3.49 V and energy efficiency over 75% (Figure 1). The method of material modification proved to be a viable way to prepare high-performance electrolyte for nonaqueous redox flow batteries.

Development on the total-organic redox flow battery will also be presented.

Acknowledgements

The authors would like to acknowledge financial support primarily from the U.S. Department of Energy’s (DOE’s) Office of Electricity Delivery and Energy Reliability (OE) (under Contract No. 57558) and the support from Laboratory-Directed Research and Development Program (LDRD) of the Pacific Northwest National Laboratory (PNNL). The NMR characterization was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, and was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is a multi-program national laboratory operated by Battelle for DOE under Contract DE-AC05-76RL01830.
3D-Nanostructures-Path to High Capacity Lithium Batteries
Authors: Prochazka Jan
Published: February 2020

Thin film technology (2D) producing lithium ion accumulators has nearly been optimized. The capacity limits are given by the thickness of the components, especialy the foils and separators.

It has been demonstrated that a significant increase of lithium battery capacity is achievable by nanostructured morphologies of the electrodes and extending of the electrode thickness from micrometers (2D) to millimeters (3D).

The HE3DA®batteries based on several millimeters thick electrodes is ideal for high capacity micro batteries and large energy storage modules.
Optimizing Electrolyte Formulations for Better Lithium-Ion Batteries
Authors: Abu-Lebdeh Yaser
Published: February 2020

In this presentation different electrolyte formulations that can improve the performance of current Li-ion batteries will be discussed. One is based on the idea of mixing ionic liquids with carbonate solvents in order to combine the advantages of the two and achieve thermally stable and nonflammable electrolyte mixtures with good cycling performance.

Another is based on aliphatic dinitriles solvents, NC-(CH2)n-CN, n = 3-8, that show good thermal and electrochemical stability (6-8 V). The variation in physical properties, crystallographic structure and battery performance of the different dinitrile-based electrolytes will be discussed.

Also, the use of these electrolyte formulations for high voltage batteries with the 4.7 V cathode material LiNi0.5Mn1.5O4 will be discussed in details.

[1] Y. Abu-Lebdeh and I. Davidson, J. Electrochem. Soc. 2009, 156 A60; J. Power Sources 2009, 189 576

[2] H. Duncan, N. Salem, Y. Abu-Lebdeh, J. Electrochem. Soc.2013, 160 A838
Digging into Electrolyte Interactions—Challenging the Conventional Wisdom
Authors: Henderson Wesley , Seo Daniel M. , Han Sang-Don , Allen Joshua L. , Yun Sung-Hyun , Daubert James S. , Borodin Oleg
Published: February 2020

The utilization of electrolytes for lithium batteries is linked with a significant body of conventional wisdom about electrolytes based largely upon assumptions—unfortunately, many of these assumptions are inaccurate. The misconstrual of the analysis of experimental data often leads to highly erroneous interpretations of electrolyte interactions. The resulting poor understanding of the molecular- and mesoscale-level solution structure of electrolytes is highly restrictive for the tailoring of new electrolyte formulations for advanced battery chemistries.

This talk will discuss the utility (or lack thereof) of solvent polarization parameters (e.g., dielectric constant (ε), Gutmann donor number (DN), etc.) for determining the strength of solvation interactions with Li+ cations, the challenges associated with using Raman spectroscopy to obtain accurate Li+cation solvation numbers and determine the solvate species present in solution, how the strength of the ionic association interactions is uncorrelated with salt solubility and how Walden plots are poorly suited for characterizing the ionic association characteristics of electrolytes. The invaluable information which may be gleaned from the fusion of experimental and computational (Fig. 1) methods will be emphasized to provide a rigorous discourse on both the phase behavior and properties of dilute electrolytes, as well as highly concentrated (> 5M ) electrolytes.

Figure 1. Snapshot of a MD simulation of a (AN)n-LiBF4mixture (n = 10 or 1.7M): (top) original MD simulation box and (bottom) same MD simulation box with the uncoordinated acetonitrile (AN) molecules colored gray and the solvates grown across the periodic boundaries (Li-purple, B-tan, F-light green).

ACKNOWLEDGEMENT

The authors wish to express their gratitude to the U.S. Department of Energy (DOE) Office of Basic Energy Science-Division of Materials Sciences and Engineering and the Vehicle Technologies Program which supported the experimental research under awards DE-SC0002169 and DE-AC02-05-CH11231.
A New Family of Anion-Binding-Agent (ABA) Based Stable Salts for Li and Li-Ion Batteries
Authors: Nagasubramanian Ganesan , Orendorff Christopher J. , Fenton Kyle R
Published: February 2020

Introduction:

Thermal instability of LiPF6 at elevated temperatures is well known. Thus there is an imminent need to develop thermally stable salt to replace LiPF6. A variety of new salts have been studied in Li-ion batteries without much success. One of the salts we are currently evaluating is LiF. This is a low molecular weight salt that has high voltage and thermal stability. However, it doesn’t dissolve in common battery solvents. This limitation can be solved with the addition of anion binding agents (ABAs). For example, Mehta and Fujinami1 proposed boroxine (tri coordinate boron ring) which is a Lewis Acid, to solubilize salt in common battery electrolyte. This compound traps the anion of the salt and frees up the Li+ for conduction. A similar idea was developed by McBreen etal
2-4 where they synthesized boron containing additives to dissolve LiF in organic solvents. However, most of the ABAs investigated are heavy with molecular weight exceeding 500 g/mole. Bulky ABAs impede access of the anion of the salt to the binding site (boron center) thus leading to poor dissolution of the salt5, 6.

Inspired by McBreen’s approach we launched a program and developed lower molecular weight (~250 g/mole) ABAs. We quickly learned that the as prepared ABAs do have DMSO solvent bound to the boron (this is designated as impure ABA). We purified the impure ABA by reacting with LiF in acetone which yielded a pure ABA+LiF salt. The purified salt gave a clear solution whereas the impure ABA+LiF salt gave a cloudy solution in EC:EMC (Photo-1).

We have prepared a variety of ABAs and tested them for electrochemical performance. Most of them could solubilize LiF only poorly and showed very low conductivity. However, two of the ABAs are promising and the results on one of them will be described here.

Electrochemical Performance:

Figure 2 compares conductivity for the pure and impure Oxalic-ABA+LiF in EC:EMC

We have prepared a variety of ABAs and tested them for electrochemical performance. Most of them could solubilize LiF only poorly and showed very low conductivity. However, two of the ABAs are promising and the results on one of them will be described here.

Electrochemical Performance:

Figure 2 compares conductivity for the pure and impure Oxalic-ABA+LiF in EC:EMC solvent blend at different temperatures. The pure ABA shows higher conductivity than the impure.

Electrochemical measurements and cell building was performed with the purified salt. This showed stability up to 4.5V vs. Li+/Li but unstable close to Li voltage, which was eliminated by adding low concentration of LiPF6 to the solution.

Figure 3 shows formation of an 18650 cell containing carbon anode, NMC (523) cathode in EC:EMC(3:7 w%)-ABA+LiF_10mM LiPF6. The reversible capacity is ~ 1.03Ahrs.
Synthesis and Characterization of Poly (ethylene glycol) Methacrylate with Sulfobetaine Pendants and Its Application as the Polymer Electrolyte
Authors: Cardoso Judith , Guzman Gregorio , Nava Dora , González I.
Published: February 2020

In the design of a lithium-ion battery, it is important the electrolyte and the polymer support. Some polyampholytes, in which both cation and anion are fixed in the polymer main chain, have showed to have a low glass transition temperature and be able to solve any kind of salts [1]. In this work, the synthesis of a methacrylate polymer, with sulphobetaine and eight etoxy residues in the side chain (PMBS-8 see Figure 1, structure 4)) was carried out to investigate the feasibility of its use as a polymer electrolyte in lithium batteries. FTIR, and 1H NMR demonstrate that the synthesis method achieves 90% functionalization. XRD spectra shows that PMBS-8 is able to dissolve LiPF6 in 1:1 (PMBS-8/ LiPF6) molar ratio. In order to improve charge transport properties and mechanical, it has been proposed the addition of non-flammable, non-volatile, room temperature ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, PYR11TFSI).

The parent polymer, is used to prepare electrolytes: polymer (PMBS-8) /LiPF6 and PMBS-8/LiPF6 / Ionic liquid (PYR11TFSI) as plasticizer. The resulting electrolyte polymers show mechanical properties akin to elastic solids. The glass transition temperature is closed at 14 °C for all specimens, and PMBS-8 is thermally stable up to 195 °C which is important since thermally stable polymers along a wide temperature range are sought for this kind of application. The conductivity of these materials which was dried carefully, varies with temperature, following an Arrhenius-like relationship. The maximum conductivity has been found to be 4.3×10−
4 S cm−
1 at room temperature for electrolyte (PMBS-8/LiPF6/PYR11TFSI).

References.

[1] J. Cardoso, G. Vazquez, I. González J. Phys Chem C, 2010, 114, 14261.
Plasmon-Enhanced Photocatalysis on TiO2-Passivated Gallium Phosphide
Authors: Cronin Stephen B.
Published: February 2020

Integrating plasmon resonant nanostructures with photocatalytic semiconductors shows great promise for highly efficient photocatalytic processes1-4. However, the electrochemical instability of most III-V semiconductors severely limits their applicability in photocatlaysis. In this work, we passivate p-type GaP with a thin layer of n-type TiO2 using atomic layer deposition. The TiO2 passivation layer prevents corrosion of the GaP, as evidenced by atomic force microscopy and photoelectrochemical measurements. In addition, the TiO2 passivation layer provides an enhancement in photoconversion efficiency through the formation of a charge separating pn-region. Plasmonic Au nanoparticles deposited on top of the TiO2-passivated GaP further increases the photoconversion efficiency through local field enhancement. These two enhancement mechanisms are separated by systematically varying the thickness of the TiO2 layer. Because of the tradeoff between the quickly decaying plasmonic fields and the formation of the pn-charge separation region, an optimum performance is achieved for a TiO2 thickness of 0.5nm. Finite difference time domain (FDTD) simulations of the electric field profiles in this photocatalytic heterostructure corroborate these results. The effects of plasmonic enhancement are distinguished from the natural catalytic properties of Au by evaluating similar photocatalytic TiO2/GaP structures with catalytic, non-plasmonic metals (i.e., Pt) instead of Au. This general approach of passivating narrower band gap semiconductors enables a wider range of materials to be considered for plasmon-enhanced photocatalysis for high efficiency water splitting.

1 Qiu, J., G. Zeng, P. Pavaskar, Z. Li and S.B. Cronin, Plasmon-Enhanced Water Splitting on TiO2-Passivated GaP Photocatalysts. Physical Chemistry Chemical Physics, 16, 3115 (2014).

2 Hung, W.H., M. Aykol, D. Valley, W.B. Hou and S.B. Cronin, Plasmon Resonant Enhancement of Carbon Monoxide Catalysis. Nano Letters, 10, 1314-1318 (2010).

3 Hou, W., Z. Liu, P. Pavaskar, W.H. Hung and S.B. Cronin, Plasmonic Enhancement of Photocatalytic Decomposition of Methyl Orange under Visible Light. J. Catal., 277, 149 (2011).

4 Liu, Z., W. Hou, P. Pavaskar, M. Aykol and S. Cronin, Plasmon Resonant Enhancement of Photocatalytic Water Splitting Under Visible Illumination. Nano Letters, 11, 1111 (2011).
Plasmon Induced Resonant Energy Transfer and Hot Electron Injection in Plasmon Enhanced Photocatalysis
Authors: Cushing Scott Kevin , Li Jiangtian , Bristow Alan D. , Wu Nick
Published: February 2020

Localized surface plasmon resonance (LSPR) is ideal for improving solar energy harvesting because of the strong, tunable absorption and scattering cross sections. The energy stored in the collective electron oscillations can be transferred to a semiconductor, allowing photoconversion at wavelengths near and above the band edge of the semiconductor. In this presentation we will investigate the mechanisms and optimization of plasmon enhanced photocatalysis using a combined transient absorption and action spectrum/IPCE analysis. Specifically, by controlling the spectral overlap, energy band alignment, and thickness of insulating barriers in metal@semiconductor nanostructures the two possible energy transfer pathways, hot electron injection and plasmon induced resonant energy transfer, are mapped out as well as the corresponding charge relaxation dynamics. A connection is made between the initial plasmonic energy transfer measured on ultrafast time scales to the resulting enhancement in photocatalysis, guiding the efficient design of plasmon enhanced photocatalysts.
Plasmonic Solar Fuels Based on Nanostructured Oxide Photocatalysts
Authors: KIM Dong Ha , Jang Yoon Hee , Kochuveedu Saji Thomas , Quan Li Na
Published: February 2020

Solar energy can be directly converted to electrical energy via photovoltaic devices. Photocatalysis provides an alternative route to the conversion of solar energy that can be stored in chemical fuels through photoelectrochemical cells or particulate photocatalytic systems. While a number of strategies were developed to overcome the deficiencies of existing semiconductors, incorporation of plasmonic nanostructures with semiconductors has gained increasing attention as a promising paradigm to improve the solar energy conversion efficiency. In this presentation, we introduce diverse approaches for the fabrication of nanostructured semiconductors integrated with plasmonic structures that can be exploited to exhibit enhanced photo-conversion efficiencies.

First, a surface plasmon (SP) induced visible light active photocatalyst system composed of silica-titania core-shell (SiO2@TiO2) nanostructures decorated with Au nanoparticles (Au NPs) was developed. The influence of size and distribution of Au NPs on photocatalysis, its fabrication methods and exploration of the mechanism of visible light activity were investigated. A favorable architecture of SiO2 beads with a thin layer of TiO2 was decorated with Au NP arrays having different size and areal density. Surface modification of SiO2@TiO2 leads to a viable and homogenous loading of Au NPs on the surface of TiO2, which renders visible light-induced photocatalytic activity on the whole TiO2 surface. An optimized system employing Au NP arrays with 15 nm size and 700/µm2 density showed best catalytic efficiency, due to a synergistic effect of the firm contact between Au NPs and TiO2 and efficiently coupled SPR excitation. A brief mechanism relating the electron transfer from surface plasmon stimulated Au NPs to the conduction band of TiO2 is proposed. The same system was further tailor-modified to exhibit far-field scattering effect, to lead to maximized performance toward solar water splitting.

Next, we focus on our design principle for the plasmon-enhanced oxide-based photocatalytic systems based on inverse opal structures and demonstrate the SP coupling effect on the efficiency of water splitting. Inverse opals of representative semiconductor oxide photocatalysts were fabricated by well-known colloid templating, and the surface was decorated with Au NPs. The effect of size and areal density of Au NP arrays were explored in terms of oxidation reactions and plasmon-enhancement effect was supported by FDTD analysis. An advance strategy to improve the efficiency of solar fuel generation includes the combined block-copolymer-based self-assembly, leading to hierarchically organized inverse opals with tailored surface area and nano-textured surface morphology. Further, we show that carbon-doped analogue inverse opal structures could be readily obtained by direct carbonization of block copolymer templates, based on which simultaneous carbon-doping and plasmon-enhancement effect are synergistically realized.
Plasmon-Induced Water Splitting System
Authors: Misawa Hiroaki
Published: February 2020

We have successfully developed a plasmon-assisted water splitting system that operates under irradiation by visible light; the system is based on the use of two sides of the same strontium titanate (SrTiO3) single crystal substrate. The water splitting system contains two solution chambers to separate hydrogen (H2) and oxygen (O2), respectively. To promote water splitting, a chemical bias was applied by pH values regulations of those chambers. The quantity of H2 evolved from the surface of platinum, which was used as a reduction co-catalyst, was twice of O2 evolved from an Au nanostructured surface. Thus, the stoichiometric evolution of H2 and O2 was clearly demonstrated. The hydrogen evolution action spectrum closely corresponds to the localized surface plasmon resonance spectrum, indicating that the plasmon-assisted charge separation at the Au/SrTiO3 interface promotes water oxidation and the subsequent reduction of a proton on the backside of the SrTiO3 substrate. We have elucidated furthermore that the chemical bias is dramatically reduced by plasmonic effects, which indicate the possibility of constructing an artificial photosynthesis system with low energy consumption.
Plasmon-Enhanced Nanoparticles in Photoelectrochemical Water Splitting
Authors: Liu Ru-Shi , Hu Shu-Fen
Published: February 2020

We report a near-infrared-driven photoelectrochemical water splitting using ZnO nanorod-array decorated with CdTe quantum dots and plasmon-enhanced upconversion nanoparticles. The plasmon enhanced the intensity of the upconversion emission, which improved the photocurrent and the gas evolution rate of the photoelectrochemical reaction greatly. We will demonstrate a process of utilizing NIR to drive the photoelectrochemical water splitting reaction. The Au-UCNs can significantly enhance the upconversion emission intensity by plasmonic effect (Fig. 1). Thus, the enhancement of photocurrent and gas evolution was achieved. The results offer a convincing demonstration that energy can be converted from NIR to chemical fuel. We believe that our strategy is fundamental to the design of solar energy devices and should become an accepted technique for solar energy utilization at the NIR and IR regions. We also etched the p-type silicon wafer to fabricate microwire array as photocathode for the artificial photosynthetic water splitting under solar irradiation. After the decoration of siliver nanoparticles, the photocurrent of silicon microwire array can be increased up to ~38 mA/cm2 under applying -1.0 V bias (Fig. 2).
Enhanced Photoelectrochemical Water Oxidation via TiO2-Coated Fluorine-Doped Tin Oxide Nanoparticle
Authors: Cordova Isvar A. , Peng Qing , Ferrall Isa L. , Rieth Adam , Hoertz Paul G. , Glass Jeffrey T.
Published: February 2020

The direct generation of hydrogen fuel from solar energy is considered to be the “holy grail” of hydrogen production. Photoelectrochemical water-splitting devices offer an opportunity to reach this goal if their efficiencies are improved. TiO2 is an attractive semiconductor anode material for PEC water-splitting electrodes because of its functionality, long-term stability in corrosive environments, nontoxicity, and low cost. Despite the extensive efforts devoted to optimizing the TiO2-based photoelectrodes, their solar-to-fuel conversion efficiencies still fall well short of their theoretical values. In this study, we report on the enhancement observed when thin TiO2 films are uniformly synthesized by atomic layer deposition (ALD) over a conductive scaffold composed of fluorine-doped tin oxide nanoparticles (nanoFTO). The conductive network of nanoFTO facilitates the efficient transport and collection of photogenerated electrons, while their intrinsic porosity increases the interfacial surface area with the electrolyte. Moreover, the decoupling of carrier diffusion and optical penetration length have the synergistic effects of maximizing photon absorption while also minimizing the diffusion length required for the photogenerated hole to reach the electrolyte/TiO2 interface. Using an effective nanoFTO scaffold thickness of 2 µm, nanostructured TiO2 samples can achieve a photocurrent density enhancement of more than 425% over TiO2 films coated over conventional planar FTO scaffolds while operating at ~60 mW/cm2 under AM 1.5 G simulated sunlight. In summary, by noting the effects of air annealing treatments on the electrochemical impedance spectroscopy (EIS) response and the incident photon to current efficiency (IPCE) spectra, we will shed light on the nature of this photoelectrochemical enhancement. These findings contribute to our understanding of the effects of nanostructuring TiO2 materials on conductive nanoparticle networks, and can aid in the development of more viable PEC water-splitting devices.
Photoelectrochemical Water Oxidation and CO2 Reduction for Artificial Photosynthesis
Authors: Park Hyunwoong
Published: February 2020

A light harvesting semiconductor electrode is a key component in photoelectrochemical (PEC) fuel generation and carbon dioxide conversion. There are several n-type and p-type semiconductors available but most of them suffer from low photoconversion efficiency, short service lifetime, and limited operation condition. There are several ways to improve the PEC performance, among which the surface modification of photoelectrode should be the simplest and most viable strategy. This study presents a few experimental results that the PEC performances of photoanodes and photocathodes are significantly improved by surface modifications including doping of elements (e.g., Li-doped TiO2 nanotube arrays, metal-doped hematite and BiVO4) and loading of catalysts (e.g., metal-deposited p-Si nanowires arrays).
Porous Coodination Networks for Artificial Photosynthesis
Authors: Ahrenholtz Spencer R , Maza William A , Morris Amanda J
Published: February 2020

Photosynthetic systems consist of light harvesting arrays and redox mediators that can funnel the electrochemical potential stored in a molecular excited state to catalytic centers to drive the oxidation of water and the reduction of CO2 to sugars. Many artificial approaches to this chemistry have been reported. Herein, we investigate porous coordination networks (PCNs) as both light harvesters and high surface area catalysts as photosynthetic mimics. PCNs combine the synthetic diversity possible with molecular catalysts and the ease of recovery of heterogeneous catalysis. Theoretically, the high surface area of PCNs can be exploited to produce a higher catalytic rate per geometric area than those realized by other approaches. Additionally, the incorporation of molecular chromophores into networks has been show to lead to enhanced luminescence quenching. We report the effects of network incorporation on homo-resonance energy transfer between molecular chromophores incorporated into a water stable PCN. Additionally, the mechanism of electron transport through PCNs is discussed. Lastly, PCNs capable of driving water oxidation and CO2/H+ reduction are presented.
Controlling the Selectivity of the CO2 Electrochemical Reduction through Anion Effects
Authors: Varela Ana Sofia , Reske Rulle , Strasser Peter
Published: February 2020

Despite over two decades of research on the CO2 electrochemical reduction the selectivity and the energy efficiency of this reaction still need to be improved. A better understanding of the factors that influence this reaction is crucial in the designing new and more efficient catalyst.

Recently, Salazar-Villalpando and co-workers have suggested that the presence of halides in the solution can facilitate the reduction of CO2 on copper. This conclusion, however, is based only the reduction currents and the reaction products were not analyzed.

In the present work we have performed CO2 electrolysis, in KHCO3 in the presence of halides (Cl-, Br-, I-). Interestingly, we observed that besides the positive effect that the presence of halides has in the reduction activity, there is also a clear effect on the selectivity of the reaction.

On copper, the efficiency towards hydrocarbons is enhancedby the presence of bromide and iodine. Remarkably, the ratio between methane and ethylene depends on which halide is in solution. In the presence of Cl- and I- both methane and ethylene are formed. By contrast, when bromide is added to the electrolyte ethylene formation is the completely suppressed and methane is the predominant product from the CO2 electrochemical reduction.

These results indicate that halides affect differently the reaction paths for methane and ethylene. Understanding this difference could be key in the overall understanding on the reaction mechanism to C2 products which is still on debate.