Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices

Constant Current ◽

Accelerated Ageing ◽

Alkaline Water ◽

Separation Membrane

A number of material coatings were investigated, specifically for 316-grade stainlesssteel electrodes, for use with alkaline water-splitting electrolysis. The aim was to enhancelongevity, particularly with respect to the highly intermittent usage that is typical of renewableenergy generation, and to increase activity. Long-term experiments were conductedover many thousands of cycles of on-off accelerated ageing at constant current density. Theeffects of ageing were analysed using chronopotentiometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy, energy dispersivex-ray spectroscopy, x-ray photoelectron spectroscopy and gas chromatography. It was foundthat titanium nitride did not have high activity for the hydrogen evolution reaction (HER),and underwent rapid oxidation and destruction if used as an anode. A new version ofelectrodeposited Raney nickel was developed that demonstrated improved activity, includingan overpotential for the HER at 10mAcm-2 of just 28 mV. As a bifunctional catalystit demonstrated an overpotential at 10mAcm-2 of just 319 mV, making it the second mostactive catalyst known, and certainly the simplest to deposit. This activity was traced to theincreased electrochemical surface area of the coating, which was higher as deposited, andincreased by up to a factor of three after ageing. During surface-area measurements, anapparent anomaly was discovered between results obtained for the same electrode via EISand CV. New methods of equivalent circuit fitting to transient waveforms were developed,and the anomaly was explained by time-domain simulations of the constant-phase elementrepresentation of the double-layer capacitance. A zero-gap electrolyser was constructed inorder to investigate its performance, and it was found that woven stainless-steel mesh couldoperate as a gas-separation membrane.

Materials Coatings and Enhanced Characterisation for Alkaline Water-Splitting Devices

10.23889/suthesis.57775 ◽

2021 ◽

Author(s):

◽

William J.F. Gannon

Keyword(s):

Surface Area ◽

Water Splitting ◽

Constant Current ◽

Accelerated Ageing ◽

Alkaline Water ◽

Separation Membrane

Woven Stainless-Steel Mesh as a Gas Separation Membrane for Alkaline Water-Splitting Electrolysis

Membranes ◽

10.3390/membranes10050109 ◽

2020 ◽

Vol 10 (5) ◽

pp. 109 ◽

Cited By ~ 1

Author(s):

William J. F. Gannon ◽

Michael E. A. Warwick ◽

Charles W. Dunnill

Keyword(s):

Stainless Steel ◽

Water Splitting ◽

Gas Separation ◽

Separation Performance ◽

Stainless Steel Mesh ◽

Alkaline Water ◽

Gas Separation Membrane ◽

Steel Mesh ◽

Separation Membrane

A 316-grade woven stainless-steel mesh membrane was investigated as a gas-separation membrane for alkaline water-splitting electrolysis. Its resistance was measured using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV), with the conclusion that it presented approximately half the resistance of a comparable commercial alternative (ZirfonTM). Its gas-separation performance was analysed using gas chromatography (GC) at 140 mA cm−2, where it achieved 99.25% purity at the hydrogen outlet of the electrolyser. This fell to 97.5% under pumped circulation, which highlights that it is sensitive to pressure differentials. Nevertheless, this mixture is still more than a factor two inside the upper flammability limit of hydrogen in oxygen. It is hoped that such a low-cost material may bring entry-level electrolysis to many hitherto discounted applications.

Organosilane-functionalization of nanostructured indium tin oxide films

Interface Focus ◽

10.1098/rsfs.2016.0056 ◽

2016 ◽

Vol 6 (6) ◽

pp. 20160056 ◽

Cited By ~ 10

Author(s):

R. Pruna ◽

F. Palacio ◽

M. Martínez ◽

O. Blázquez ◽

S. Hernández ◽

...

Keyword(s):

Surface Area ◽

Indium Tin Oxide ◽

Annealing Treatment ◽

Electrochemical Analysis ◽

Cyclic Voltammograms ◽

X Ray ◽

Chip Technology ◽

Significant Difference

Fabrication and organosilane-functionalization and characterization of nanostructured ITO electrodes are reported. Nanostructured ITO electrodes were obtained by electron beam evaporation, and a subsequent annealing treatment was selectively performed to modify their crystalline state. An increase in geometrical surface area in comparison with thin-film electrodes area was observed by atomic force microscopy, implying higher electroactive surface area for nanostructured ITO electrodes and thus higher detection levels. To investigate the increase in detectability, chemical organosilane-functionalization of nanostructured ITO electrodes was performed. The formation of 3-glycidoxypropyltrimethoxysilane (GOPTS) layers was detected by X-ray photoelectron spectroscopy. As an indirect method to confirm the presence of organosilane molecules on the ITO substrates, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were also carried out. Cyclic voltammograms of functionalized ITO electrodes presented lower reduction-oxidation peak currents compared with non-functionalized ITO electrodes. These results demonstrate the presence of the epoxysilane coating on the ITO surface. EIS showed that organosilane-functionalized electrodes present higher polarization resistance, acting as an electronic barrier for the electron transfer between the conductive solution and the ITO electrode. The results of these electrochemical measurements, together with the significant difference in the X-ray spectra between bare ITO and organosilane-functionalized ITO substrates, may point to a new exploitable oxide-based nanostructured material for biosensing applications. As a first step towards sensing, rapid functionalization of such substrates and their application to electrochemical analysis is tested in this work. Interestingly, oxide-based materials are highly integrable with the silicon chip technology, which would permit the easy adaptation of such sensors into lab-on-a-chip configurations, providing benefits such as reduced size and weight to facilitate on-chip integration, and leading to low-cost mass production of microanalysis systems.

Effect of Water Vapor and SOx in Air on the Cathodes of Solid Oxide Fuel Cells

MRS Proceedings ◽

10.1557/proc-1041-r03-10 ◽

2007 ◽

Vol 1041 ◽

Cited By ~ 4

Author(s):

Seon Hye Kim ◽

Toshihiro Ohshima ◽

Yusuke Shiratori ◽

Kohei Itoh ◽

Kazunari Sasaki

Keyword(s):

Water Vapor ◽

Solid Oxide Fuel Cells ◽

Degradation Mechanism ◽

Chemical Species ◽

Cell Voltage ◽

Ambient Air ◽

Open Circuit ◽

Constant Current ◽

Constant Current Density

AbstractAmbient air is used as an oxygen source in SOFCs to be commercialized. Various chemical species which can lead to poisoning of SOFC cathodes are included as minor constitutions in air, such as water vapor, SOx, NOx and NaCl etc. However, their effects on the cathode performance have not yet well known, even though they are expected to cause a degradation of the electrode performance and to reduce the long-term durability of SOFCs. Therefore, in this study, we focused on the poisoning caused by water vapor and SOx in the oxygen source to clarify their effects on SOFCs performances and to reveal the degradation mechanism of cathodes. SOFCs with typical electrolyte-supported structure were used in this work, which were composed with ScSZ (10 mol% Sc2O3, 1mol% CeO2, 89 mol% ZrO2) plate with the thickness of 200 µm as electrolyte, NiO-ScSZ (mixture of 56 wt% NiO and 44 wt% ScSZ) porous layer as anode, and two cathode layers of LSM ((La0.8Sr0.2)0.98MnO3) and LSM-ScSZ (mixture of 50 wt% LSM and 50 wt% ScSZ). Power generation characteristics of the cells had been analyzed by measuring cell voltage at a constant current density (200 mA/cm2) and by comparing changes in cell impedance, upon supplying the artificially-contaminated air with water vapor or SOx, to the SOFC cathodes at various operational temperatures. High-resolution FESEM (S-5200, Hitachi) was used to analyze microstructural changes caused by the impurities. Mg Kα radiation from a monochromatized X-ray source was used for XPS measurements (ESCA-3400, KRATOS). AC impedance was measured at various temperatures under the open circuit voltage condition by an impedance analyzer (Solatron 1255B/SI 1287, Solatron), in a frequency range from 0.1 to 105 Hz with an amplitude of 10 mV.

Effect of SO2 on the Performance of LSCF Cathode

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.902.41 ◽

2014 ◽

Vol 902 ◽

pp. 41-44 ◽

Cited By ~ 2

Author(s):

Run Ru Liu ◽

De Jun Wang ◽

Leng Jing

Keyword(s):

Electrochemical Performance ◽

Microstructural Change ◽

Cell Performance ◽

Sulfur Poisoning ◽

Constant Current ◽

Sofc Cathode ◽

Galvanic Current ◽

Poisoning Effect

Sulfur poisoning effect on the electrochemical performance and long-term durability of SOFC cathode has been investigated for La0.6Sr0.4Co0.2Fe0.8O3(LSCF) by Galvanic Current Interruption (GCI) technology. Cell performance was measured supplying with SO2-containing air to the cathode under a constant current density of 200 mA cm-2. At 800 °C, LSCF cathode showed low tolerance to the sulfur poisoning. SO2tends to react with strontium in LSCF material resulting in the formation of SrSO4in the cathode. This reaction gave rise to microstructural change in the cathode and caused gradual degradation of cell performance.

S-containing and Si-containing compounds as highly effective electrolyte additives for SiOx -based anodes/NCM 811 cathodes in lithium ion cells

Scientific Reports ◽

10.1038/s41598-019-49568-1 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 6

Author(s):

Fuqiang An ◽

Hongliang Zhao ◽

Weinan Zhou ◽

Yonghong Ma ◽

Ping Li

Keyword(s):

Elevated Temperatures ◽

Solid Electrolyte Interphase ◽

Lithium Ion ◽

Reversible Capacity ◽

High Energy ◽

High Energy Density ◽

Full Cell

Abstract Recently, high-energy density cells containing nickel-rich cathodes and silicon-based anodes have become a practical solution for increasing the driving range of electric vehicles. However, their long-term durability and storage performance is comparatively poor because of the unstable cathode-electrolyte-interphase (CEI) of the high-reactivity cathode and the continuous solid-electrolyte-interphase (SEI) growth. In this work, we study several electrolyte systems consisting of various additives, such as S-containing (1,3,2-dioxathiolane 2,2-dioxide (DTD), DTD + prop-1-ene-1,3-sultone (PES), methylene methanedisulfonate (MMDS)) and Si-containing (tris(trimethylsilyl) phosphate (TTSP) and tris(trimethylsilyl) borate (TMSB)) compounds, in comparison to the baseline electrolyte (BL = 1.0 M LiPF6 + 3:5:2 w-w:w EC: EMC: DEC + 0.5 wt% lithium difluoro(oxalato)borate (LiDFOB) + 2 wt% lithium bis(fluorosulfonyl)imide (LiFSI) + 2 wt% fluoroethylene carbonate (FEC) + 1 wt% 1,3-propane sultone (PS)). Generally, electrolytes with Si-containing additives, particularly BL + 0.5% TTSP, show a lower impedance increase in the full cell, better beginning-of-life (BOL) performance, less reversible capacity loss through long-term cycles and better storage at elevated temperatures than do electrolytes with S-containing additives. On the contrary, electrolytes with S-containing additives exhibit the advantage of low SEI impedance but yield a worse performance in the full cell than do those with Si-containing additives. The difference between two types of additives is attributed to the distinct function of the electrodes, which is characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS), which was performed on full cells and half cells with fresh and harvested electrodes.

Borocarbonitride Layers on Titanium Dioxide Nanoribbons for Efficient Photoelectrocatalytic Water Splitting

Materials ◽

10.3390/ma14195490 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5490

Author(s):

Nuria Jiménez-Arévalo ◽

Eduardo Flores ◽

Alessio Giampietri ◽

Marco Sbroscia ◽

Maria Grazia Betti ◽

...

Keyword(s):

Water Splitting ◽

Vapour Deposition ◽

Chemical Vapour ◽

Photoelectrochemical Cell ◽

Flat Band ◽

X Ray Diffraction ◽

X Ray ◽

Reflectance Measurements

Heterostructures formed by ultrathin borocarbonitride (BCN) layers grown on TiO2 nanoribbons were investigated as photoanodes for photoelectrochemical water splitting. TiO2 nanoribbons were obtained by thermal oxidation of TiS3 samples. Then, BCN layers were successfully grown by plasma enhanced chemical vapour deposition. The structure and the chemical composition of the starting TiS3, the TiO2 nanoribbons and the TiO2-BCN heterostructures were investigated by Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Diffuse reflectance measurements showed a change in the gap from 0.94 eV (TiS3) to 3.3 eV (TiO2) after the thermal annealing of the starting material. Morphological characterizations, such as scanning electron microscopy and optical microscopy, show that the morphology of the samples was not affected by the change in the structure and composition. The obtained TiO2-BCN heterostructures were measured in a photoelectrochemical cell, showing an enhanced density of current under dark conditions and higher photocurrents when compared with TiO2. Finally, using electrochemical impedance spectroscopy, the flat band potential was determined to be equal in both TiO2 and TiO2-BCN samples, whereas the product of the dielectric constant and the density of donors was higher for TiO2-BCN.

Impact of the Temperature in the Evaluation of Battery Performances During Long-Term Cycling—Characterisation and Modelling

Applied Sciences ◽

10.3390/app8081364 ◽

2018 ◽

Vol 8 (8) ◽

pp. 1364 ◽

Cited By ~ 4

Author(s):

Odile Capron ◽

Joris Jaguemont ◽

Rahul Gopalakrishnan ◽

Peter Van den Bossche ◽

Noshin Omar ◽

...

Keyword(s):

Experimental Data ◽

Discharge Current ◽

Lithium Ion ◽

High Energy ◽

Constant Current ◽

Accelerated Ageing ◽

Nickel Manganese ◽

Cycling Temperature ◽

Battery Cells

This paper presents the results regarding the thermal characterisation and modelling of high energy lithium-ion battery cells at both room (25 °C) and cycling (35 °C) temperatures. In this work two types of Nickel Manganese Cobalt (NMC) batteries are studied: a fresh (or uncycled) and an aged (or cycled) battery cells. The ageing of the studied NMC battery cells is achieved by means of accelerated ageing tests (i.e., repetition of numerous charge and discharge cycles) at 35 °C cycling temperature. Temperature at the surface of the battery cells is characterised, with a set of three discharge current rates 0.3C (i.e., 6 A), 1C (i.e., 20 A) and 2C (i.e., 40 A), and the evolutions at three different locations on the surface of the battery cells namely, at the top, in the center and at the bottom regions are measured. In addition, temperature and ageing dependent electrochemical-thermal modelling of the uncycled and cycled battery cells is also successfully accomplished in case of both room and cycling temperatures. Numerical simulations were carried out in case of high 2C constant current rate, and the assessment of the modelling accuracy by comparison of the predicted battery cells voltage and temperature with respect to the experimental data is further presented. With this paper, thermal performances of battery cells prior and after long-term cycling are evaluated at the cycling temperature, next to the ambient temperature. Hence, thermal characterisation and modelling results are more closely reflecting that encountered by the battery cells in real cycling conditions, so that their performances are believed in this way to be more objectively evaluated.

From Chip Size to Wafer-Scale Nanoporous Gold Reliable Fabrication Using Low Currents Electrochemical Etching

Nanomaterials ◽

10.3390/nano10112321 ◽

2020 ◽

Vol 10 (11) ◽

pp. 2321

Author(s):

Pericle Varasteanu ◽

Cosmin Romanitan ◽

Alexandru Bujor ◽

Oana Tutunaru ◽

Gabriel Craciun ◽

...

Keyword(s):

Surface Area ◽

Electrochemical Etching ◽

Nanoporous Gold ◽

Constant Current ◽

Etching Time ◽

Average Pore ◽

Systematic Analysis ◽

Porosity Evolution ◽

The Impact

We report a simple, scalable route to wafer-size processing for fabrication of tunable nanoporous gold (NPG) by the anodization process at low constant current in a solution of hydrofluoric acid and dimethylformamide. Microstructural, optical, and electrochemical investigations were employed for a systematic analysis of the sample porosity evolution while increasing the anodization duration, namely the small angle X-ray scattering (SAXS) technique and electrochemical impedance spectroscopy (EIS). Whereas the SAXS analysis practically completes the scanning electronic microscopy (SEM) investigations and provides data about the impact of the etching time on the nanoporous gold layers in terms of fractal dimension and average pore surface area, the EIS analysis was used to estimate the electroactive area, the associated roughness factor, as well as the heterogeneous electron transfer rate constant. The bridge between the analyses is made by the scanning electrochemical microscopy (SECM) survey, which practically correlates the surface morphology with the electrochemical activity. The results were correlated to endorse the control over the gold film nanostructuration process deposited directly on the substrate that can be further subjected to different technological processes, retaining its properties. The results show that the anodization duration influences the surface area, which subsequently modifies the properties of NPG, thus enabling tuning the samples for specific applications, either optical or chemical.

Hierarchical NiCo2O4/NiFe/Pt heterostructures supported on nickel foam as bifunctional electrocatalysts for efficient oxygen/hydrogen production

RSC Advances ◽

10.1039/c9ra07012e ◽

2019 ◽

Vol 9 (60) ◽

pp. 34995-35002 ◽

Cited By ~ 1

Author(s):

Qingyou Huang ◽

Yang Cao ◽

Xiaohong Wang ◽

Jinchun Tu ◽

Qianfeng Xia ◽

...

Keyword(s):

Hydrogen Production ◽

Water Splitting ◽

Current Density ◽

Nickel Foam ◽

Water Electrolysis ◽

Constant Current ◽

Photographic Image ◽

Overall Water Splitting ◽

Scan Rate

(a) LSV of overall water splitting for the respective component at a scan rate of 5 mV s−1. (b) Chronopotentiometry curve under a constant current density of 20 mA cm−2. Inset: photographic image of two-electrode water electrolysis device.