bluuebunny/crossref_metadata_2025 huggingface dataset:
High Field Modulated Field Effect Transistors Coated By Ion Selective Membrane for Cadmium Ion Detection in Water
Authors: Hsieh Ching-Yen , Wang Shin-Li , Chen Yi-Ting , Wang Yu-Lin
Published: February 2020

Cadmium is one among the most hazardous heavy metals. Heavy metal cannot be metabolized or digested by human body, therefore, heavy metal accumulates in our body through time. Cadmium in human body causes lung cancer, osteomalacia and even proteinuria. Mostly cadmium ions get in to human body by ingestion, so detecting cadmium ion in drinking water, tap water and liquid form of food is very important. However, traditional laboratory detection methods of cadmium ion are complex and time consuming and requires heavy and expensive machinery. Though the electrochemical ion selective electrode is easy to use, its poor stability and larger detection limit are huge disadvantages. In this research, we devised a small size, high sensitivity, low detection limit, short response time and easy to fabricate cadmium ion selective membrane field effect transistor (ISMFET). This device is easy to use and can measure the cadmium concentration in water quickly with the combination of ion-selective membrane and field effect transistor. The sensing mechanism depends on electrical double layer (EDL) gating coupled with high electric field to enhance the sensitivity of ISHEMT beyond the limit of ideal Nernst sensitivity. World Health Orgnization (WHO) suggests that cadmium ion in drinking water should be lower than 3 ppb, equal to 2.68 10-8 M. This device can detect cadmium ion concentration form 10-7 M to 10-11 M, covering the wide dynamic range according to WHO’s suggestion. Such high sensitivity and low detection limits devices are highly desirable for consumers who intend to regularly monitor the water quality, for food and environmental safety. In contrast, testing cadmium ion in water by ICP-MS takes several hours and the instrument occupies larger space. To improve the yield and sensitivity of our sensor, we are studying on different condition of ISM. With this cadmium, ISMFET, we can determine the cadmium concentration in water in 15 minutes and even higher sensitivity and lower detection limit, in comparison with conventional laboratory based techniques. Not only Cadmium, but also other heavy metals, for example lead and mercury, can use similar methodology to get better detection time and detection limit. This design makes quality monitoring of water we consume in daily life become much easier and convenient.
(Invited) Standardization of Triboelectric Nanogenerators: Progress and Perspectives
Authors: Zi Yunlong
Published: February 2020

The rapid development of the Internet of Things (IoT) and the increasing energy crisis call for a new type of energy sources. Triboelectric nanogenerators (TENGs), which can convert mechanical energies to be electricity, develop quickly in recent years and catch more and more people’s eyes in the world. Meanwhile the importance of the standardization for TENG has been emphasized, and developing the standardized theoretical models and experimental methods to evaluate the performance quantitatively becomes more and more important for the commercialization and industrialization of the TENG technology. This presentation will systematically review the origin of the V-Q plot based standardized characterization methods and the figure-of-merits (FOM) based the standard for quantitatively charactering the energy output. This presentation will also discuss several essential factors, including the input energy, environmental factors, and life-time assessment, to be potentially involved in standards for TENGs in future. The standardization of TENG will be great helpful to understand and improve this emerging energy harvester towards further applications. We believe the standardization of TENG will greatly facilitate the commercialization and industrialization of TENGs in future.
(Invited) Controlled Homo-Epitaxial Growth of Hybrid Halide Perovskites
Authors: Xu Sheng
Published: February 2020

Organic–inorganic hybrid perovskites have demonstrated tremendous potential for the next-generation electronic and optoelectronic devices due to their remarkable carrier dynamics. Current studies are focusing on polycrystals, since controlled growth of high quality single crystals is extremely challenging. In this presentation, I will discuss the first chemical epitaxial growth of single crystal hybrid halide perovskites with controlled locations, morphologies, and orientations, using combined strategies of advanced microfabrication, homoepitaxy, and low temperature solution method. The growth is found to follow a layer-by-layer model. A light emitting diode array, with each perovskite crystal as a single pixel, with enhanced quantum efficiencies than its polycrystalline counterparts is demonstrated. This approach opens up broad opportunities for hybrid halide perovskite materials based high performance electronic and optoelectronic devices.
(Invited) what Limits the Intrinsic Carrier Mobility of Two Dimensional Metal Dichalcogenides?
Authors: Liu Yuanyue
Published: February 2020

Two-dimensional (2D) metal dichalcogenides (MX2) are the most common type of 2D semiconductors and have shown great potential for a wide range of chemical and physical applications. However, they are limited by a low electron/hole mobility, which has been recognized as one of the major challenges impeding their further developments, and urges efforts to understand the mobility-limiting factors and discovery of higher-mobility alternatives. Here using density functional perturbation theory and Wannier interpolation of the electron–phonon matrix to study a wide range of MX2, we find that the intrinsic carrier mobility, in contrast to common belief, neither correlates with the effective mass nor can be assessed by the widely used deformation potential theory; instead it is limited by the longitudinal optical (LO) phonon scattering for most MX2, while for MoS2 and WS2, the mobility is limited by the longitudinal acoustic (LA) phonon scattering. Furthermore, we find that the LO scattering strength is strongly correlated with the magnitude of the Born effective charge, suggesting that the carrier transport is greatly affected by the electric polarization change induced by the atomic vibration. This finding enables us to use the Born effective charge to rapidly screen the 2D MX2 database for high-mobility semiconductor candidates. Our work reveals the underlying factors governing the intrinsic carrier mobility of 2D MX2, and offers a practical descriptor for discovering high-mobility candidates.

Ref: L. Cheng, Y. Liu, JACS, 2018, DOI: 10.1021/jacs.8b07871
Fully Bioabsorbable Capacitor As an Energy Storage Unit for Implantable Medical Electronics
Authors: Li Hu , Li Zhou , Fan Yubo
Published: February 2020

Implantable medical electronic devices are usually powered by batteries or capacitors, which have to be removed from the body after completing their function due to their non-biodegradable property. Here, a fully bioabsorbable capacitor (BC) is developed for life-time implantation. The BC has a symmetrical layer-by-layer structure, including PLA supporting substrate, PLA nanopillar arrays, self-assembled zinc oxide nanoporous layer and PVA/PBS hydrogel. The as-fabricated BC can not only work normally in air but also in a watery environment, including PBS and animal body. Long-term normal work time was achieved to 30 days in PBS and 50 days in SD rats. The work time of BC in the watery environment was tunable from days to weeks by adopting different encapsulations along BC edges. The operation voltage of BC reached up to 1.5 V. Capacitance retention of 70 % was achieved after 3000 cycles. Three BCs in series can light up fifteen green LEDs in vivo. Additionally, after completing its mission, the BC can be fully degraded in vivo and rebsorbed by a Sprague Dawley (SD) rat. Considering these performance, the developed BC has a great potential as a fully bioabsorbable power source for transient electronics and implantable medical devices.
(Invited) Cell-Devices Interface: From Single Cell to 3D Tissue Analysis
Authors: Li Chen Zhong
Published: February 2020

Direct detection and analysis of biomolecules and cells in physiological microenvironment is urgently needed for fast evaluation of biology and pharmacy. The past several years has witnessed remarkable development opportunities in vitro models from single cell to 3D tissue with multiple functions based on microfluidic devices, termed as “cell/organ-on-a-chip”. By recapitulating the multicellular architectures, cell-cell interfaces and physicochemical microenvironments, these devices enable high-resolution, real time sensing and in vitro analysis of biochemical, genetic and metabolic activities of living cells/tissues in a functional tissue and organ context. This lecture will outline our recent research activities for the fundamental study of physical and electrical properties of cells, as well as the development of a new generation of cell/organ on chips that combine aspects of “top-down” nanofabrication approach with a “bottom-up” self-assembly method for cell and tissue measurements. Several newly developed live cell integrated biosensors will be introduced including: 1). Biosensors for single cell analysis; 2). Chip based sensing device for whole cell recording and for neuron mapping upon nanomaterials and drug molecules exposure. The biosensors can monitor crucial cell signaling networks cell metabolic pathways, as well as detecting diseases in their earliest stage, titrating drug effects and enabling worldwide remote diagnosis. (No Image Selected)
An in-Situ Impedance-Based Whole Blood Anticoagulation Diagnosis Technology
Authors: Huang Yi-Chen , Jheng Jhu-Siang , Chiang Kuang-Hsing , Lin Chih-Ting
Published: February 2020

The detection of anticoagulant dosage in blood is important and necessary in clinical operations. With high anticoagulant dosage, it results in heavy bleeding during surgery. With low anticoagulant dosage, in the opposite, it leads to clotting problem. To monitor the dosage, in traditional, optical-inspection instrumentations, such as PT (Prothrombin Time) and APTT (Activated Partial Thromboplastin Time), are commonly used in hospitals. However, the processes of PT and APTT measurements are complicated and time-consuming. To address these issues, in this work, electrical impedance analysis is employed to monitor the anticoagulant dosage in the whole blood samples obtained from rats. To optimize the impedance analysis, several electrode designs are implemented and examined. Based on the experimental results, a good electrode configuration for blood coagulation measurement is tested with whole blood extracted from rats. In brief, heparin is used as the anticoagulant and different dosages were injected into the blood samples. For control experiments, at the same time, the same volume of isotonic saline were injected into the blood samples. Based on impedance spectrum analysis, both experimental sets and control sets can be recorded. Utilizing linear regression method, in addition, the regression lines of different concentration of anticoagulant dosage in the whole-blood samples can be distinguished. Comparing the slops extracted from the regressions of both experimental sets and control sets, it shows control sets' slope approaches 0, low concentration (1.5×10-3 units heparin/mL) experimental sets' slope is below 10, and high concentration (7.5×10-4 units heparin/mL) experimental sets' slope is above 10. According to the aforementioned experimental results, the more heparin adds, the larger slop value can be extracted. As a consequence, this work demonstrates a potential micro devices for fast anticoagulant dosage monitoring and it could be contributed in clinical applications.
(Invited) visco-Poroelastic & Iontronic Pump: New Strategy for Ultrasensitive Artificial Skin Sensors
Authors: Kim Do Hwan
Published: February 2020

Creating artificial sensor skins that shows the tactile- and chemical-sensing capability of human skin has been a big challenge in wearable sensor research. In particular, biomimetics has emerged as a burgeoning area in the field of deformable tactile sensor skins that has led innovations in material designing and device structure manipulation with the aim of imitating multimodal sensing features of human skin intelligently.

Herein, inspired by the sophisticated physiological sensing mechanism of living cells, we describe a uniquely designed visco-poroelastic, iontronic pump consisting of artificial ions confined into polymeric network matrix or well-designed hybrid interface. Novel bottom-up strategy employed here resulted into supramolecular polymer networks through non-covalent interactions between poroelastic artificial ions and viscoelastic polymer chains, which endows effective iontronic pumping under mechanical stimuli and electronic field, simultaneously. This design for visco-poroelastic, iontronic, and ion confined artificial mechanoreceptors allows for ultrasensitive mechanosensing over a wide spectrum of pressure (Pa~150kPa) beyond capabilities of human skin. Moreover, our devices could visualize the local variation in the applied pressure or electronic field without using spatially distributed device arrays.
(Invited) Flexible Nanogenerators for Energy Harvesting and Self-Powered Biomedical Devices
Authors: Xie Yannan
Published: February 2020

Recently, flexible electronics have experienced a rapid development and are dramatically desirable for commercial, medical, and military applications. Conventional flexible biomedical sensors usually require external power-supply devices whose small power density and limited lifetime dramatically hinder the speedy advancement of this field. To solve the above issues, self-powered sensing technology has been introduced and attracted significant interests as a crucial alternative. The self-powered active sensor will generate electricity as a response to the external stimuli and the electric signal can reversely reflect the impact of the outside trigger. Therefore, it is able to effectively and independently work without any external power sources and hence its accelerated progress is of great significance to the prevalence of wearable and flexible sensors.

Originated from Maxwell’s displacement current, nanogenerator (NG) based on triboelectric effects have been developing rapidly for efficiently harvesting environmental mechanical energy and self-powered active sensor. Triboelectric nanogenerator (TENG) relied on a conjunction of triboelectrification and electrostatic induction has shown numerous advantages, including large output, high efficiency, low cost, simple fabrication, light weight, and being environmental friendly. Besides mechanical energy, thermal energy is another important energy source especially for wearable electronics. The temperature difference (ΔT) between human body and surrounding environment always exists and can be used as driving force for electric energy generation through Seebeck effect. But the ΔT need to be furtherly enhanced. In our living environment, in addition to the direct heat source, light source (such as the infrared light) can also provide thermal energy through the photothermal effect. Based on the photothermal effect and Seebeck effect, photo-thermoelectric generator has been rapidly developed for converting photo energy into electricity without a spatial temperature gradient in the environment.

In our works, flexible NGs based on triboelectric effect and photo-thermoelectric effect have been demonstrated and designed for wearable electronics. The electric signals obtained from the NGs not only can be acted as direct energy sources for flexible devices but also used for self-powered biomedical applications, such as human motion monitoring, temperature sensing, anti-bacterial treatment, and so on.
(Invited) Flexible Human-Machine Interfaces and Damage Robust Stretchable Optoelectronics
Authors: Tee Benjamin CK
Published: February 2020

Electronic devices and machines are undergoing exciting form factor evolutions by adopting formats closer to human skins[1–5]. At the same time, almost all forms of human-machine interfaces require electrically activated light sources to facilitate the interactions. These emerging trends present challenges as well as opportunities for innovations in light emitting devices that are robust to mechanical strains and even severe electro-mechanical damage. Self-healing materials have been shown to be useful in electronic devices and impart repeatable healing of electro-mechanical performance[6,7]. At the same time, stretchable light sources have been demonstrated for applications in soft robotics and touch interfaces[8]. In my talk, I will discuss recent progress in pressure sensor designs, as well as our efforts to develop a stretchable and damage robust opto-electronic materials.

References

[1] C. M. Lochner, Y. Khan, A. Pierre, A. C. Arias, Nat. Commun.
2014, 5, 1.

[2] Z. Huang, Y. Hao, Y. Li, H. Hu, C. Wang, A. Nomoto, T. Pan, Y. Gu, Y. Chen, T. Zhang, W. Li, Y. Lei, N. Kim, C. Wang, L. Zhang, J. W. Ward, A. Maralani, X. Li, M. F. Durstock, A. Pisano, Y. Lin, S. Xu, Nat. Electron.
2018, 1, 473.

[3] L. Y. Chen, B. C. K. Tee, A. L. Chortos, G. Schwartz, V. Tse, D. J. Lipomi, H. S. P. Wong, M. V McConnell, Z. Bao, Nat. Commun.
2014, 5, 1.

[4] D.J. Lipomi, B.C.K. Tee, M. Vosgueritchian, Z. Bao, Adv. Mater.
2011, 23, 1771.

[5] B. C. K. Tee, A. Chortos, A. Berndt, A. K. Nguyen, A. Tom, A. McGuire, Z. C. Lin, K. Tien, W. G. Bae, H. Wang, P. Mei, H. H. Chou, B. Cui, K. Deisseroth, T. N. Ng, Z. Bao, Science (80-. ).
2015, 350, 313.

[6] Y. J. Tan, J. Wu, H. Li, B. C. K. Tee, ACS Appl. Mater. Interfaces
2018, 10, 15331.

[7] B. C.-K. Tee, C. Wang, R. Allen, Z. Bao, Nat. Nanotechnol.
2012, 7, 825.

[8] S. Li, B. N. Peele, C. M. Larson, H. Zhao, R. F. Shepherd, Adv. Mater.
2016, 28, 9770.
(Invited) Ferromagnetic, Folded, Soft Composite Material for Skin‐Interfaced Electrodes
Authors: Jang Kyung-In
Published: February 2020

A class of ferromagnetic, folded, soft composite material for skin‐interfaced electrodes with releasable interfaces to stretchable, wireless electronic measurement systems is introduced. These electrodes establish intimate, adhesive contacts to the skin, in dimensionally stable formats compatible with multiple days of continuous operation, with several key advantages over conventional hydrogel‐based alternatives. The reported studies focus on aspects ranging from ferromagnetic and mechanical behavior of the materials systems, to electrical properties associated with their skin interface, to system‐level integration for advanced electrophysiological monitoring applications. The work combines experimental measurement and theoretical modeling to establish the key design considerations. These concepts have potential uses across a diverse set of skin‐integrated electronic technologies.
(Invited) Two-Dimensional Material Derived Supercapacitor Yarns As Weaveable Energy-Storage Units
Authors: Gao Wei
Published: February 2020

We demonstrate how 2D-material derived fibers can be fabricated into high-performance yarn supercapacitors for real applications via industrialized fiber/yarn manufacturing processes. Our 2D-material composite fibers possess balanced mechanical properties and electrical conductivity, with an areal capacitance of 342.59 mF cm-2, seventeen times higher than that from pure graphene fibers. In addition, electrolyte mediation process has been adopted in our recipe to improve electrode wettability, electrolyte diffusion, and specific capacitance (550.96 mF cm-2), exceeding most of state-of-the-art fiber electrodes. These composite fibers can be further twisted into yarn electrodes, followed by electrolyte coating to derive yarn supercapacitors. An energy density of 52.4 μWh cm-2 at a power density of 943.2 μW cm-2 has been achieved in our system, together with good bending stability.
High Efficiency Multi-Level Flexible Triboelectric Nanogenerator for Wearable Electronics
Authors: Ravichandran Aravind , Ramuz Marc , Blayac Sylvain
Published: February 2020

With the rapid development of wearable electronics and sensor networks, batteries cannot meet the sustainable energy requirement due to their limited lifetime, size and degradation. With miniaturization leading to high-power and robustness, triboelectric nanogenerators(TENGs) have been conceived as a promising technology by harvesting mechanical energy to power small electronics and wearables. The main issues associated with TENGs are their very low output power leading to lower output charge density and high impedance matching.

In this work, a state of the art multilayer flexible structure is devised which not only increases the charge density but also provides a high average power output. Thin-film organic flexible materials are deposited to acquire charges from the triboelectrification process, allowing the acceptance of more charges from an electrode and thereby increasing the power output. Material work function provide better understanding towards charge transfer process.

A proof of concept device is conceptualized for use in a highly efficient self-powered sensor network system, converting ambient mechanical energy to electricity with a 1.2kV peak amplitude and a very high device performance. This device structure makes the TENGs attractive to charging applications for wearables and large-scale harvesting without massive volume. By this technique, we have overcome numerous friction-based operation challenges including lack of uniform contact, material loss through wear, high sensitivity to humidity, and output power storage.

By considering these merits of simple fabrication, outstanding performance, robust characteristic and low-cost technology, we believe that multi level flexible TENGs can open great opportunities not only for powering small electronics but can contribute to large-scale energy harvesting through engineering design being complementary to existing energy sources.
(Invited) Multifunctional Mxene-Based Fibres
Authors: Razal Joselito
Published: February 2020

Yarn-shaped supercapacitors (YSCs) once integrated into fabrics provide promising energy storage solutions to the increasing demand of wearable and portable electronics. In such device format, however, it is a challenge to achieve outstanding electrochemical performance without compromising flexibility. Metal carbides or carbonitrides called “MXene” has presented a distinct combination of very high conductivity (~10,000 S cm-1), volumetric capacitance (~1,500 F cm-3), and hydrophilic properties. To date, however, MXene-based fibers or yarns that can be used for wearable applications have been relatively unexplored. Their small sheet size (<2 µm) and weak inter-sheet interactions have made it challenging to fabricate MXene-based fibers or yarns. Here, we present strategies to achieve fibers or yarns from Ti3C2 MXene. Our works include high-performance yarn supercapacitors fabricated by coating MXene on conductive carbon fiber bundles. This device showed length capacitance of ~132 mF cm-1 higher than the literature reports (typically lower than 100 mF cm-1) even at low mass loading of 2 mg cm-1. We also used wet-spinning technique by taking advantage of the templating role of liquid crystalline (LC) graphene oxide (GO) to produce fibres with high MXene content of ~88 wt. %. These fibres demonstrate excellent flexibility and a high volumetric capacitance of ~341 F cm-3. We also employed biscrolling technique to scroll MXene nanosheets within carbon nanotube helical corridors. Here, the yarns are predominantly MXene containing up to ~98 wt.% MXene yielding an areal capacitance as high as ~3,188 mF cm−2, which exceeds the previously recorded performance for any fiber or yarn supercapacitor electrode. The supercapacitor prototype in asymmetric configuration reached a maximum energy and power densities of ~61.6 mWh cm–3 and ~5428 mW cm–3 respectively. We show that the MXene-based fibers and yarns are useful for powering small electronic devices when knitted or woven into a textile. Our works have introduced a new class of fibers that can be excellent candidates for integration within textile-based electronics and wearable devices.
The Catalytic Roles of Surface Transition Metals on the Hydrogen Evolution/Oxidation Reactions of Pt-Surfaces in Base
Authors: Liu Ershuai , Jiao Li , Mukerjee Sanjeev , Jia Qingying
Published: February 2020

Despite the importance of the hydrogen evolution and oxidation reactions (HER/HOR) to modern electrocatalysis, their sluggish kinetics in alkaline remains unclear. Recent efforts have shown that surface deposition of transition metals on platinum electrode can dramatically affect the HER and/or HOR performance. However, the catalytic roles of the second metal are unclear. For some of the metals (such as Mn and Fe) it even remains inconclusive whether they are beneficial or detrimental to the HER/HOR performance.1,2Herein, we systematically investigated the catalytic roles of several transition metals including Mn, Fe, Co, Ni, Cu, and Ru by electrochemically depositing them onto Pt surfaces. We conclusively show that all the studied metal except for Cu benefits the HER of Pt surfaces, whereas only Ni (marginally) and Ru benefits the HOR. On the basis of these electrochemical results and in situx-ray absorption spectroscopy data. we propose that the second metal on the surface impact the HER/HOR kinetics via affecting the transportation of the hydroxide throughout the double layer region. This finding may help to rationalize bimetallic mechanism for HER/HOR in alkaline.

(1) Rebollar, L.; Intikhab, S.; Snyder, J. D.; Tang, M. H. Determining the Viability of Hydroxide-Mediated Bifunctional HER/HOR Mechanisms through Single-Crystal Voltammetry and Microkinetic Modeling. J. Electrochem. Soc.
2018, 165, J3209-J3221.

(2) Subbaraman, R.; Tripkovic, D.; Chang, K.-C.; Strmcnik, D.; Paulikas, A. P.; Hirunsit, P.; Chan, M.; Greeley, J.; Stamenkovic, V.; Markovic, N. M. Trends in activity for the water electrolyser reactions on 3d M (Ni, Co, Fe, Mn) hydr (oxy) oxide catalysts. Nat. Mater.
2012, 11, 550-557.

Figure 1
(Invited) The Cation Effects on the Alkaline HER/HOR Kinetics
Authors: Jia Qingying , Liu Ershuai , Jiao Li , Mukerjee Sanjeev
Published: February 2020

The sluggish kinetics of the hydrogen evolution and oxidation reactions (HER/HOR) in base remains unclear despite the fundamental importance of these reactions. Herein, we show that increasing the alkali metal cation (AM+) concentration promotes the HER while varying the identity of AM+ affects both HER/HOR. On the basis of these observations, we conclude that the presence of solvated AM+ anchored by OHad (OHad-(H2O)x-AM+) have two effects: (1) facilitating the OHad removal into the bulk forming OH--(H2O)x-AM+
as per the hard-soft acid-base (HSAB) theory, which selectively promotes the HER and makes the sharp HUPD peaks associated with the exchange of H/OH less reversible; (2) weakening the OHad binding energy to the surface, which hinders the HOR and the CO oxidation as per the bifunctional mechanism.
Isotope-Labeling Studies in Water Oxidation Electrocatalysis
Authors: Scott Soren B. , Sørensen Jakob E. , Kibsgaard Jakob , Chorkendorff Ib
Published: February 2020

Improving understanding of the electrocatalytic mechanisms for the oxygen evolution reaction (OER) will help in designing electrode materials with lower catalytic overpotential and greater stability, increasing the efficiency and economic viability of electrolysis. Isotope-labeling can be a powerful tool for elucidating catalytic mechanisms, including in electrocatalysis. Herein, we apply 18-O labeling, utilizing a fully quantitative electrochemistry - mass spectrometry method with unprecedented sensitivity[1] and post-characterization by low-energy ion scattering spectrometry, to investigate the electrocatalytic mechanism of oxygen evolution.

Nickel-iron based electrodes are used in industrial alkaline water electrolysis, but questions remain about the intrinsic activity and electrocatalytic mechanism. By performing a series of isotope-labeling experiments on a model system of mass-selected Ni-Fe nanoparticles, we show that oxygen evolution does not proceed via lattice oxygen exchange and that only the surface of the nanoparticles are active[2]. This allows us to estimate the turn-over frequency of the active sites, 6 O2 molecules per site per second, which is higher than previous estimates. We also quantify lattice oxygen exchange in IrO2 and RuO2 thin films during oxygen evolution in acidic electrolyte as a function of electrochemical roughening, and perform oxygen stripping experiments to probe OER intermediates. This talk will describe these findings and further explore the potential of isotope labeling studies in electrocatalysis.

[1] D. B. Trimarco, S. B. Scott et al, Enabling real-time detection of electrochemical desorption phenomena with sub-monolayer sensitivity. Electrochimica Acta. 2018, 268, 520-530

[2] C. Roy, B. Sebok, S. B. Scott et al, Impact of nanoparticle size and lattice oxygen on water oxidation on NiFeOxHy. Nature Catalysis. 2018, 1(11), 820–829

Figure 1
Functionalized Phosphorene Quantum Dots As Efficient Electrocatalyst for Oxygen Evolution Reaction
Authors: Prasannachandran Ranjith , Vineesh Thazhe Veettil , Anil Athira , Krishna B Murali , Shaijumon Manikoth M
Published: February 2020

Two-dimensional layered materials[1] have been of great interest due to their unique physico-chemical properties and wide range of applications. Wide interest in exfoliated 2D layered materials such as graphene[2] and transition metal dichalcogenides (TMDs) motivated scientists to explore similar layered materials and, phosphorene, a layered counterpart of black phosphorous[3], has attracted lot of attention in recent times. The high air sensitivity and chemical reactivity of mono/few-layered phosphorene remain a big challenge in its synthesis and further applications. Here, a novel strategy for controlled synthesis and in situ surface functionalization of phosphorene quantum dots (PQDs) using a single step electrochemical exfoliation process from bulk black phosphorous crystals is demonstrated. Further, our results prove promising potential of phosphorenes as technologically viable OER electrodes for water splitting devices.

Keywords: Phosphorene; Electrochemical synthesis; Oxygen Evolution Reaction

References

[1] S. Z. Butler, S. M. Hollen, L. Cao, Y. Cui, J. A. Gupta, H. R. Gutiérrez, T. F. Heinz, S. S. Hong, J. Huang, A. F. Ismach, E. Johnston-Halperin, M. Kuno, V. V. Plashnitsa, R. D. Robinson, R. S. Ruoff, S. Salahuddin, J. Shan, L. Shi, M. G. Spencer, M. Terrones, W. Windl, J. E. Goldberger, ACS Nano
2013, 7, 2898-2926.

[2] A. K. Geim, Science
2009, 324, 1530.

[3] L. Kou, C. Chen, S. C. Smith, The Journal of Physical Chemistry Letters
2015, 6, 2794-2805.
Vanadium Based Full Water Splitting Electrocatalysts
Authors: Saxena Apurv , Masud Jahangir , Nath Manashi
Published: February 2020

Recently, alternative energy research has focused on attempting to produce hydrogen efficiently by splitting water in an electrochemical and photoelectrochemical process. However, the efficiency of water splitting reaction is limited by the challenging anodic oxygen evolution reaction (OER), which is an energy-exhaustive 4 electron process, leading to a kinetically slow step and significant efficiency loss. Thus, an efficient electrocatalyst is required to enhance the OER process. The most active and stable electrocatalysts are based on precious metals like ruthenium and iridium in dimensionally stable anodes working in harsh environments which limits their application to industrial processes. A tremendous development has been obtained in the water-splitting research using transition metal chalcogenides-based nanomaterials. Here, we demonstrate vanadium selenide (V1.04Se2) electrocatalysts for oxygen evolution reaction (OER) in alkaline solution.

The catalyst was synthesized hydrothermally using vanadium pentaoxide and selenium dioxide. The synthesized vanadium selenide was characterized by XRD, XPS, SEM, TEM, and EDS for morphology, elemental chemical compositions, particle distribution. The OER catalytic activity and stability was performed in 1M KOH solution. The vanadium selenide required only 270 mV overpotential to achieve the 50mA cm-2 OER current and with a low Tafel slope value. It showed excellent stability under continuous oxygen generation condition for an extended period. The details of catalyst synthesis, characterization and activity will be presented in the meeting.
(Invited) Developing Thin and Tunable Catalyst –Coated Liquid/Gas Diffusion Layers with Ultralow Catalyst Loadings
Authors: Zhang Feng-Yuan
Published: February 2020

The thin liquid/gas diffusion layers (LGDLs) with well-tunable pore morphologies are developed by employing advanced manufacturing and show significant performance improvements in proton exchange membrane electrolyzer cells (PEMECs) for hydrogen/oxygen production and renewable energy storage. In addition, the LGDL thickness reduction from hundreds of µm for conventional LGDLs to tens of µm will decrease the weight and volume of the PEMEC stack. More importantly, by taking advantage of the novel material development coupled with a transparent PEMEC and a high-speed micro visualization system, the electrochemical reactions are revealed to occur only on the catalyst layer adjacent to good electrical conductors. Based on these findings, new fabrications of thinfilm catalyst depositions on the novel LGDLs exhibit much higher mass activity than conventional catalyst-coated membranes. This discovery presents an opportunity to enhance the multiphase interfacial effects, maximizing the use of the catalysts and significantly reducing the cost of these electrochemical devices. Furthermore, the well-tunable features of thin electrodes, including pore size, pore shape, pore distribution, and thus porosity and permeability, will be very valuable for developing models and validating simulations of electrochemical energy devices.
(Invited) Surface Engineered Ptm-O Alloy for High Hydrogen Evolution Reaction Rate at Low Overpotential
Authors: Huang Yu
Published: February 2020

The generation of hydrogen is an essential step inthe energy cycle of hydrogen, a promising renewable fuel. Both electrical and photoelectrical water splitting involves the hydrogen evolution reaction (HER), which provides an environment-friendly route to produce hydrogen(H2) from water. Pt-based catalysts possess the best HER catalytic performances, butthe high cost and scarcity of platinum limittheir practical application. Thus, new Pt-based catalysts with a significantly improved HER performance are essential. Here I present our recent development of PtM alloys with surface decorated with Ni(OH)2islands, which demonstrate a record high activity and outstanding stability towards HER catalysis.
Development of Supported Iridium Oxides As the Low Noble Metal Loading Anode for PEM Water Electrolyser
Authors: Shi Yan , Lu Zhuoxin , Tan Hongyi , Guo Changqing , Wang Zhida , Yan Changfeng
Published: February 2020

Reducing the cost of PEM water electrolyser is still a big challenge for renewable energy storage. Though there are some reports which have achieved very low Ir loading (0.1~0.2mg/cm2) in membrane electrode assemblies (MEA) for PEM water electrolyser, the other issues such as the performance and stability of MEA, the reduction of Pt loading in cathode and the scalability of preparation method of MEA still need further investigation for developing low cost and high performance PEM water electrolyser.

In this work, to develop high performance anode with low Ir loading, highly active Iridium oxohydroxides were supported on conductive titanium metal nanosphere as the anode catalyst. The diatmeter of metal Ti nanosphere ranges from 60-200nm, and the Iridium oxohydroxides loaded on Ti support shows a particle size between 1.5-3nm. The OER activity of the catalyst with various Ir loading was characterized, and the catalyst with 10% Ir loading exhibited highest Ir mass activity (1700A/g @η=0.37V), it is about 6 times as the commercial IrO2. Increasing the loading of Ir will lead to the decline of Ir mass activity, this may be due to the limited surface area of Ti nanosphere. The stability of the catalyst (Ir loading 10%) was characterized by CV scans between 0.4-1.5V (vs.RHE) in 0.5M H2SO4. After 2000 cycles, the active sites of IrOx declined only 18%, and the catalyst does not show an obviously rising in resistance from EIS characterization, indicating a good stability both on active sites and support.

The MEAs using such IrOx/Ti as the anode were prepared by conventional CCM method, and the Pt loading (20% wt. Pt/C) in cathode was reduced to about 0.2mg/cm2. The anode with various Ir loading and membrane with different thickness were determined at atmosphere under 80 degrees. The electrolyser with Ir loading 0.13mg/cm2 in anode, Pt loading 0.18mg/cm2 in cathode and N212 membrane achieved 1.623V at 1A/cm2 and 1.778V at 2A/cm2, which exhibits a good performance with such low noble metal loading. Further decreasing the Ir loading in anode catalyst layer will lead to performance degradation, but the rising of voltage was only 50-60mv at 1A/cm2 when Ir was reduced to 0.08 mg/cm2. With respect of the durability of MEAs, an electrolyser using Nafion 117 as the membrane, and 0.08 mg /cm2 Ir in MEA was tested under 1A/cm2. After 850h, the voltage increased from 1.79V to 1.83V, and the degradation rate is below 50μV/h, this suggests a good stability of supported Iridium oxohydroxides, and the stability of electrolyser with N212 membrane is now ongoing.

Figure 1
(Invited) Structural Design Via Group Energy Materials for High-Efficient Photoelectrochemical Hydrogen Evolution Reaction
Authors: Zheng Xueli , Cui Yi
Published: February 2020

Photoelectrochemical hydrogen evolution reaction (HER) and electrochemical reduction of carbon dioxide (CO2RR) to chemical fuels have the potential to relieve the energy problem. The performance of these devices depends intimately on the properties of their materials. Herein we modify the inorganic sulfide by organic polymer molecules and thus improve the electronic and band structure, optimization the overall hydrogen evolution performance. Meanwhile, earth-abundant first-row (3d) transition-metal-based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials significantly above thermodynamic requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxy-hydroxide materials with an atomically homogeneous metal distribution. These gelled FeCoW oxy-hydroxide exhibits the lowest overpotential (191 mV) reported at 10 milliamperes per square centimeter in alkaline electrolyte. The catalyst shows no evidence of degradation following more than 500 hours of operation. X-ray absorption and computational studies reveal a synergistic interplay between W, Fe and Co in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER. We also used in operando soft X-ray absorption to quantify the ratio of the Ni4+ and Ni2+ active site, achieved an OER overpotential of only 330 mV under neutral condition, better than novel metal oxide catalyst, IrO2, with ideal stability within 100 h. With the modulating of 3d coordination environment and electronic structure, maximum optimization the energetics of oxygen evolution reaction, we finally achieved the lowest over potential for OER and hence improved the HER efficiency. Furthermore, we engineered the metal sites by using non-metal element and which significantly improved the efficiency of CO2RR to formate.
Electronic Properties of the Co3O4 Photoelectrode: Predictions from First-Principles Calculations
Authors: Pham Tuan Anh , Smart Tyler , Ping Yuan , Ogitsu Tadashi
Published: February 2020

Cobalt Oxide (Co3O4) has emerged as a highly promising material for hydrogen generation through photoelectrochemical cells (PECs); however, a detailed understanding of the electronic properties of this material is largely lacking. This includes the band gap and electrical conductivity of the photoelectrode, which are important factors in determining the performance of PECs. For example, contradicting experimental results have been reported for the optical gap of Co3O4, leading to two commonly reported values of 0.8 eV and 1.6 eV. In this work, we have employed first-principles calculations based on Density Functional Theory to support that the intrinsic band gap of Co3O4 is 1.6 eV. Meanwhile, we show that the 0.8 eV transition found experimentally is due to the presence of polaron or defect states. In particular, our calculations predict the spontaneous formation of electron and hole polarons, that in turn exhibit significant contribution to the absorption spectra of the material, and are responsible for the optical excitation at 0.8 eV. Finally, we resolve the nature of the stable spin states of electron and hole polarons, and we discuss how the interaction between polarons with n-type dopants, such as carbon, could improve the electrical conductivity of this intrinsic p-type material.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
(Invited) Development and Practical Verification of the Redox Flow Battery in SEI
Authors: Shigematsu Toshio
Published: February 2020

More than 40 years have passed since the basic principle of the Redox Flow Battery (RFB) was proposed by NASA. Currently, with the widespread use of renewable energy, demand for energy storage batteries is increasing more and more. MW class RFBs are already in practical use in electric power systems. On the other hand, further improvement of performance and cost reduction are urgent issues for mass introduction of RFBs. A wide variety of research and development activities are being conducted all over the world.

The development of RFBs in Japan began with AIST, a national laboratory aimed at the load-leveling of electric power companies in the 1970s. SEI began development as a collaborative research project with a power company in 1985 and has been developing first the Fe/Cr RFB followed by the V/V RFB for commercialization. Along with changes in the situation of the power industry for many years, SEI has delivered about 30 RFBs from large batteries to small ones according to customer's request.

In particular, since the establishment of the FIT system in Japan in 2012, a large amount of PV systems has been introduced and the need for energy storage batteries is rapidly rising. With the support of METI (the Ministry of Economy, Trade and Industry), a 15 MW RFB was installed in 2015 and is currently operated by Hokkaido Electric Power Company.

In this presentation I will introduce the power situation and the necessity of energy storage in Japan, the history of RFB development in SEI, and the operation experience of some systems. SEI is also developing a new electrolyte technology using titanium and manganese ions, which is one of our latest developments aimed at cost reduction. I would like to introduce these developments as well.

References

[1] T. Shigematsu, SEI Technical Review, 73, 4(2011)

[2] Y. R. Dong, et.al., ECS Trans., 69 (18), 59 (2015)

[3] H. Kaku, et.al., ECS Trans., 72 (10), 1 (2016)
Low Cost Zinc-Iron Rechargeable Flow Battery with High Energy Density
Authors: Accogli Alessandra , Gianellini Matteo , Panzeri Gabriele , Gibertini Eugenio , Magagnin Luca
Published: February 2020

In current research, electrochemical energy storage systems have gaining interest because they constitute an essential element in the development of sustainable energy technologies [1,2]. Among them, rechargeable flow batteries (RFBs) are one of the most promising technology for the integration in grid-connected electricity, especially if combined with unpredictable and intermittent renewable energy sources, due to their high efficiency, power/energy independent sizing and room temperature operation [3]. At the moment, among all RFBs systems, the most investigated and advanced technology is the vanadium based RFB, characterized by an energy efficiency equal to 80% and energy density in the range 15-45 Wh/l [4]. However, nowadays the main bulk of research is focused on finding an economically convenient and technically competitive flow battery chemistry, able to ensure long lifetime and high energy efficiency [5,6]. In this study, a zinc-iron RFB with low cost and high energy density will be presented. In particular, inorganic electrolytes based on high soluble salts have been developed, achieving a charge density of 55-70 Wh/l. We report the use of a new electrolyte as mid acidic solution for zinc electrodeposition, which can not only improve the electrolyte conductivity but also reduce the risk of zinc dendritic growth. Moreover, the developed electrolytes have been characterized by means of cyclic voltammetries in order to investigate the effect of different additives on the electrochemical properties. The combination of high energy efficiency of the Zn-Fe RFB, in the order of 70- 75% at 25 mAcm-2, with its ability to withstand a large number of charge/discharge cycles and the low cost, makes this battery system suitable for energy storage applications.

References

P. Alotto, M. Guarnieri, and F. Moro. Renewable and Sustainable Energy Reviews (2014) 29, 325-335.

A. Z. Weber, M.M. Mench,, J.P. Meyers, P.N. Ross, J.T. Gostick and Q. Liu. Journal of Applied Electrochemistry (2011), 41(10), 1137.

G. Kear, A.A Shah, and F.C. Walsh. International journal of energy research, (2012), 36(11), 1105-1120.

C. Ding, H. Zhang, X. Li, T. Liu, and F. Xing. The Journal of Physical Chemistry Letters, (2013), 4(8), 1281-1294.

C- Xie, Y. Duan, W. Xu, H. Zhang, and X Li. Angewandte Chemie International Edition, (2017) 56(47), 14953-14957.

S. Selverston, R. F. Savinell, and J. S. Wainright. Journal of The Electrochemical Society (2017) 164(6), A1069-A1075.
A Quinone-Based Redox Flow Battery at Near-Neutral pH with Record Capacity Retention Rate
Authors: Ji Yunlong , Goulet Marc-Antoni , Pollack Daniel , Kwabi David G. , Jin Shijian , De Porcellinis Diana , Kerr Emily , Gordon Roy G. , Aziz Michael J.
Published: February 2020

A highly stable functionalized anthraquinone is introduced as the redox-active material in a negative potential electrolyte (negolyte) for aqueous redox flow batteries operating at nearly neutral pH. The design and synthesis of the molecule, which has a high solubility at pH 9 and above, is described. Chemical stability studies demonstrate high stability at both pH 9 and 12. By pairing it with a potassium ferri/ferrocyanide positive electrolyte across an inexpensive, non-fluorinated permselective polymer membrane, this near-neutral quinone-based aqueous flow battery exhibits an open-circuit voltage of 1.0 V and a capacity fade rate of 0.00036% / cycle and 0.014% / day, which is the lowest ever reported for any flow battery in the absence of rebalancing processes. It is further demonstrated that the negolyte pH drifts upward upon atmospheric oxygen penetration but, when oxygen is excluded, oscillates reversibly between 9 and 12 during cycling. These results enhance the suitability of aqueous-soluble redox-active organics for use in large-scale energy storage, potentially enabling massive penetration of intermittent renewable electricity.