scholarly journals Dry Hydrogen Production in a Tandem Critical Raw Material-Free Water Photoelectrolysis Cell Using a Hydrophobic Gas-Diffusion Backing Layer

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1319 ◽  
Author(s):  
Stefano Trocino ◽  
Carmelo Lo Vecchio ◽  
Sabrina Campagna Zignani ◽  
Alessandra Carbone ◽  
Ada Saccà ◽  
...  
Keyword(s):  
Energy Gap ◽  
Cupric Oxide ◽  
Free Water ◽  
High Energy ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Solid Polymer ◽  
Oxide Glass ◽  
Semiconductor Surface ◽  
Backing Layer

A photoelectrochemical tandem cell (PEC) based on a cathodic hydrophobic gas-diffusion backing layer was developed to produce dry hydrogen from solar driven water splitting. The cell consisted of low cost and non-critical raw materials (CRMs). A relatively high-energy gap (2.1 eV) hematite-based photoanode and a low energy gap (1.2 eV) cupric oxide photocathode were deposited on a fluorine-doped tin oxide glass (FTO) and a hydrophobic carbonaceous substrate, respectively. The cell was illuminated from the anode. The electrolyte separator consisted of a transparent hydrophilic anionic solid polymer membrane allowing higher wavelengths not absorbed by the photoanode to be transmitted to the photocathode. To enhance the oxygen evolution rate, a NiFeOX surface promoter was deposited on the anodic semiconductor surface. To investigate the role of the cathodic backing layer, waterproofing and electrical conductivity properties were studied. Two different porous carbonaceous gas diffusion layers were tested (Spectracarb® and Sigracet®). These were also subjected to additional hydrophobisation procedures. The Sigracet 35BC® showed appropriate ex-situ properties for various wettability grades and it was selected as a cathodic substrate for the PEC. The enthalpic and throughput efficiency characteristics were determined, and the results compared to a conventional FTO glass-based cathode substrate. A throughput efficiency of 2% was achieved for the cell based on the hydrophobic backing layer, under a voltage bias of about 0.6 V, compared to 1% for the conventional cell. For the best configuration, an endurance test was carried out under operative conditions. The cells were electrochemically characterised by linear polarisation tests and impedance spectroscopy measurements. X-Ray Diffraction (XRD) patterns and Scanning Electron Microscopy (SEM) micrographs were analysed to assess the structure and morphology of the investigated materials.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

A p–n fusion strategy to design bipolar organic materials for high-energy-density symmetric batteries

2021 ◽  
Author(s):  
Jihyeon Kim ◽  
Heechan Kim ◽  
Sechan Lee ◽  
Giyun Kwon ◽  
Taewon Kang ◽  
...  
Keyword(s):  
Energy Density ◽  
Organic Material ◽  
Energy Gap ◽  
High Energy ◽  
High Energy Density ◽  
Lumo Energy ◽  
Fusion Strategy ◽  
Redox Active ◽  
Bipolar Type ◽  
Homo Lumo

A new bipolar-type redox-active organic material with a wide HOMO–LUMO energy gap is designed though the ‘p–n fusion’ strategy.

scholarly journals Mass Transport Limitations of Water Evaporation in Polymer Electrolyte Fuel Cell Gas Diffusion Layers

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2967
Author(s):  
Adrian Mularczyk ◽  
Andreas Michalski ◽  
Michael Striednig ◽  
Robert Herrendörfer ◽  
Thomas J. Schmidt ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Evaporative Cooling ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Ex Situ ◽  
Water Evaporation ◽  
Evaporative Water ◽  
Gas Diffusion Layers ◽  
Diffusion Layers

Facilitating the proper handling of water is one of the main challenges to overcome when trying to improve fuel cell performance. Specifically, enhanced removal of liquid water from the porous gas diffusion layers (GDLs) holds a lot of potential, but has proven to be non-trivial. A main contributor to this removal process is the gaseous transport of water following evaporation inside the GDL or catalyst layer domain. Vapor transport is desired over liquid removal, as the liquid water takes up pore space otherwise available for reactant gas supply to the catalytically active sites and opens up the possibility to remove the waste heat of the cell by evaporative cooling concepts. To better understand evaporative water removal from fuel cells and facilitate the evaporative cooling concept developed at the Paul Scherrer Institute, the effect of gas speed (0.5–10 m/s), temperature (30–60 °C), and evaporation domain (0.8–10 mm) on the evaporation rate of water from a GDL (TGP-H-120, 10 wt% PTFE) has been investigated using an ex situ approach, combined with X-ray tomographic microscopy. An along-the-channel model showed good agreement with the measured values and was used to extrapolate the differential approach to larger domains and to investigate parameter variations that were not covered experimentally.

Properties of Epitaxial SrTiO3 Thin Films Grown on Silicon by Molecular Beam Epitaxy

1999 ◽  
Vol 567 ◽  
Author(s):  
Z. Yu ◽  
R. Droopad ◽  
J. Ramdani ◽  
J.A. Curless ◽  
C.D. Overgaard ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
High Energy ◽  
State Density ◽  
Unit Cell ◽  
Ex Situ ◽  
Silicon Oxide Layer ◽  
Single Crystalline ◽  
X Ray

ABSTRACTSingle crystalline perovskite oxides such as SrTiO3 (STO) are highly desirable for future generation ULSI applications. Over the past three decades, development of crystalline oxides on silicon has been a great technological challenge as an amorphous silicon oxide layer forms readily on the Si surface when exposed to oxygen preventing the intended oxide heteroepitaxy on Si substrate. Recently, we have successfully grown epitaxial STO thin films on Si(001) surface by using molecular beam epitaxy (MBE) method. Properties of the STO films on Si have been characterized using a variety of techniques including in-situ reflection high energy electron diffraction (RHEED), ex-situ X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Auger electron spectroscopy (AES) and atomic force microscopy (AFM). The STO films grown on Si(001) substrate show bright and streaky RHEED patterns indicating coherent two-dimensional epitaxial oxide film growth with its unit cell rotated 450 with respect to the underlying Si unit cell. RHEED and XRD data confirm the single crystalline nature and (001) orientation of the STO films. An X-ray pole figure indicates the in-plane orientation relationship as STO[100]//Si[110] and STO(001)// Si(001). The STO surface is atomically smooth with AFM rms roughness of 1.2 AÅ. The leakage current density is measured to be in the low 10−9 A/cm2 range at 1 V, after a brief post-growth anneal in O2. An interface state density Dit = 4.6 × 1011 eV−1 cm−2 is inferred from the high-frequency and quasi-static C-V characteristics. The effective oxide thickness for a 200 Å STO film is around 30 Å and is not sensitive to post-growth anneal in O2 at 500-700°C. These STO films are also robust against forming gas anneal. Finally, STO MOSFET structures have been fabricated and tested. An extrinsic carrier mobility value of 66 cm2 V−11 s−1 is obtained for an STO PMOS device with a 2 μm effective gate length.

Comparison of Water Thickness Profiles of Compressed PEMFC GDLs

2011 ◽  
Author(s):  
Pradyumna Challa ◽  
James Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Water Injection ◽  
Liquid Water Content ◽  
Gas Diffusion ◽  
Injection Rate ◽  
Water Levels ◽  
Ex Situ

In this paper, through-plane liquid water distribution is analyzed for two polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). The experiments were conducted in an ex situ flow field apparatus with 1 mm square channels at two distinct flow rates to mimic water production rates of 0.2 and 1.5 A/cm2 in a PEMFC. Synchrotron radiography, which involves high intensity monochromatic X-ray beams, was used to obtain images with a spatial and temporal resolution of 20–25 μm and 0.9 s, respectively. Freudenberg H2315 I6 exhibited significantly higher amounts of water than Toray TGP-H-090 at the instance of breakthrough, where breakthrough describes the event in which liquid water reaches the flow fields. While Freudenberg H2315 I6 exhibited a significant overall decrease in liquid water content throughout the GDL shortly after breakthrough, Toray TGP-H-090 appeared to retain breakthrough water-levels post-breakthrough. It was also observed that the amount of liquid water content in Toray TGP-H-090 (10%.wt PTFE) decreased significantly when the liquid water injection rate increased from 1 μL/min to 8 μL/min.

Generating Innovative Solid Polymer Electrolyte Based on Melanin and Without Binder for High Energy Li Batteries

2021 ◽  
Vol 105 (1) ◽  
pp. 29-34
Author(s):  
Elena Shembel ◽  
Yuliya Polishchuk ◽  
Volodymyr Kyrychenko ◽  
Volodymyr Redko ◽  
Boris A Blyuss ◽  
...  
Keyword(s):  
High Temperature ◽  
Polymer Electrolyte ◽  
Chemical Stability ◽  
Solid Polymer Electrolyte ◽  
Operating Temperature ◽  
High Energy ◽  
Solid Polymer ◽  
Special Design ◽  
Li Batteries ◽  
Wide Operating

The goal of this investigation is connected with wishes to use the melanin for formulating the solid polymer electrolyte without the binder for Li batteries. Nature and properties of solid polymer electrolyte of the Li batteries is an important factor for ensuring the properties of Li batteries. For successful optimization the properties of Li batteries the following list includes the important requirements for the polymer electrolyte: high conductivity in wide operating temperature, chemical stability and no ignition at under high temperature - even more than 1000C, low impedance of interface between electrode and solid polymer electrolyte, special design of system - the solid polymer electrolyte in porous structure of electrode. For developing the solid polymer electrolyte without the binder we fulfill this goal includes the melanin in the solid polymer electrolyte.

Temperature/Doping-Dependency of the Electrical Properties of the Nickel Doped Copper Oxide Thin Films

2021 ◽  
Vol 16 (2) ◽  
pp. 163-169
Author(s):  
Alaa Y. Mahmoud ◽  
Wafa A. Alghameeti ◽  
Fatmah S. Bahabri
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Electrical Properties ◽  
Thermal Activation ◽  
Doping Concentration ◽  
Energy Gap ◽  
Cupric Oxide ◽  
Electrical Energy ◽  
Thermal Activation Energy ◽  
Ni Doping

The electrical properties of the Nickel doped cupric oxide Ni-CuO thin films with various doping concentrations of Ni (0, 20, 30, 70, and 80%) are investigated at two different annealing temperatures; 200 and 400 °C. The electrical properties of the films; namely thermal activation energy and electrical energy gap are calculated and compared. We find that for the non-annealed Ni-CuO films, both thermal activation energy and electrical energy gap are decreased by increasing the doping concentration, while for the annealed films, the increase in the Ni doping results in the increase in thermal activation energy and electrical energy gap for most of the Ni-CuO films. We also observe that for a particular concentration, the annealing at 200 °C produces lower thermal activation energy and electrical energy gap than the annealing at 400 °C. We obtained two values of the activation energy varying from -5.52 to -0.51 eV and from 0.49 to 3.36 eV, respectively, for the annealing at 200 and 400 °C. We also obtained two values of the electrical bandgap varying from -11.05 to -1.03 eV and from 0.97 to 6.71 eV, respectively, for the annealing at 200 and 400 °C. It is also noticeable that the increase in the doping concentration reduces the activation energy, and hence the electrical bandgap energies.

Study on the Durability Comparsion of STS316 Non-Coated and CrN Coated for Metallic Bipolar Plate

2012 ◽  
Vol 538-541 ◽  
pp. 402-405
Author(s):  
M.S. Moon ◽  
Kee Do Woo ◽  
J.H. Oh ◽  
J.H. Song ◽  
S.J. Kang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Bipolar Plate ◽  
High Energy ◽  
Transportation System ◽  
Gas Diffusion ◽  
Machining Process ◽  
Membrane Electrode ◽  
Light Weight ◽  
Plate Material ◽  
New Energy

Nowadays, many economists and scientist worry about sharply increased to fuel consumption. New energy sources have to be investigation now. This was a base on the low-emission gas, high-energy efficiency, permanence and possible with co-generation. Especially, transportation system has been restricted to system’s total weight. Light weight of a transportation system offers to increase performance. By using light weight in a transportation system, it gives another benefit that reduced oil consumption, improved fuel efficiency and increased Market-value. Fuel cell is one of the new energy systems for next generation. Normally, fuel cell consists of bipolar plate, MEA (Membrane Electrode Assembly) and GDL (Gas Diffusion Layer). Conventional bipolar plate material was used to graphite. Graphite has been very weak at external shock. Machining process is not easy, and the main problem is that the graphite material supplied by oxidizing and reducing agent composition of the gas leak comes. Thus, the manufacturing cost is increased by this reason. This study will be tried to bipolar plate material replacement from graphite materials to metallic material. In this experiment, STS316 base on austenite stainless steel was used. This experiment was observing an effect of surface conditions with corrosion behavior with Non-coated and CrN coated STS316 on a similar PEMFC operating condition. By the results of experimental, CrN coated condition has better corrosion resistance than that of Non-coated condition due to passivation layer on CrN coated surface.

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