| 1. |
- Ahvenniemi, Esko, et al.
(författare)
-
Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"
- 2017
-
Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 35:1
-
Forskningsöversikt (refereegranskat)abstract
- Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency.
|
|
| 2. |
- Etula, Jarkko, et al.
(författare)
-
Room-Temperature Micropillar Growth of Lithium-Titanate-Carbon Composite Structures by Self-Biased Direct Current Magnetron Sputtering for Lithium Ion Microbatteries
- 2019
-
Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 29:42
-
Tidskriftsartikel (refereegranskat)abstract
- Here, an unidentified type of micropillar growth is described at room temperature during conventional direct-current magnetron sputtering (DC-MS) deposition from a Li4Ti5O12+graphite sputter target under negative substrate bias and high operating pressure. These fabricated carbon-Li2O-TiO2 microstructures consisting of various Li4Ti5O12/Li2TiO3/LixTiO2 crystalline phases are demonstrated as an anode material in Li-ion microbatteries. The described micropillar fabrication method is a low-cost, substrate independent, single-step, room-temperature vacuum process utilizing a mature industrial complementary metal-oxide-semiconductor (CMOS)-compatible technology. Furthermore, tentative consideration is given to the effects of selected deposition parameters and the growth process, as based on extensive physical and chemical characterization. Additional studies are, however, required to understand the exact processes and interactions that form the micropillars. If this facile method is further extended to other similar metal oxide-carbon systems, it could offer alternative low-cost fabrication routes for microporous high-surface area materials in electrochemistry and microelectronics.
|
|
| 3. |
- Jukka-Pekka, Spets, et al.
(författare)
-
Test of Different Anode Electrocatalysts for Direct Glucose Anion Exchange Membrane Fuel Cell
- 2016
-
Ingår i: International Journal of Electrochemical Science. - : Electrochemical Science Group. - 1452-3981. ; 11:6, s. 4219-4230
-
Tidskriftsartikel (refereegranskat)abstract
- Direct glucose anion exchange membrane fuel cell (AEMFC) with near-neutral-state electrolyte of 0.1 M [PO4] (tot) was studied with five different anode electrocatalysts (Pt, PtRu, PtNi, Au, PdAu) at a temperature of 37 degrees C and at a glucose concentration of 0.1 M. The cathode catalyst in each test was Pt supported on carbon (60 wt.%). Four anode electrocatalysts (supported on carbon) had a total metal content of 40 wt.% while the fifth anode material of PtRu had a higher content of 60 wt.%. Moreover, in order to show the influence of the metallic content on the fuel cell performance, anode catalysts with 60 wt.% (Pt) and 10wt.% (PtNi) were tested. The operation of the AEMFC was controlled by means of an in-house-made electronic load with PI-controller (i.e. a feedback controller that has proportional and integral action on control error signal) either at constant current (CC) or at constant voltage (CV). The primary objective was to characterize the Coulombic efficiency (CE) based on the exchange of two electrons and compare the specific energy (Wh kg(-1)) for the direct glucose AEMFC related to the different electrode combinations and electrocatalysts. As a result of these screening tests, two most efficient anode electrodes with Pt and PtNi were selected to be used for further AEMFC studies.
|
|
| 4. |
- Jukka-Pekka, Spets, et al.
(författare)
-
Towards an Efficient Direct Glucose Anion Exchange Membrane Fuel Cell System with Several Electro-Oxidation Units
- 2017
-
Ingår i: International Journal of Electrochemical Science. - : ESG. - 1452-3981. ; 12:5, s. 3697-3708
-
Tidskriftsartikel (refereegranskat)abstract
- This work covers the direct glucose anion exchange membrane fuel cell (AEMFC) with near-neutralstate electrolyte of 0.1 M [PO4] (tot) having two high-performing anode electrocatalysts (Pt and PtNi) at 37 degrees C and at a glucose concentration of 0.1 M. The cathode catalyst in each test was a Pt supported on carbon (60 wt.%). The PtNi/C had a total metal content of 40 wt.% and the Pt/C 60 wt.%. The operation of the AEMFC was controlled by means of an in-house made electronic load with PI-controller (i.e. a feedback controller, which has proportional and integral action on control error signal). There were two primary objectives with this study. At first, to find out how the electrode modifications of the anode (i.e. by increasing the thicknesses of these electrodes by adding extra carbon) affect the Coulombic efficiency (CE, based on the exchange of two electrons) and the specific energy (SPE, Wh kg(-1)) values of the direct glucose AEMFC. Secondly, investigate how a two-stage fuel cell system with two fuel cells concatenated and used one after the other for the electrochemical oxidation of glucose, influence the CE and SPE values. The results show that the modified PtNi anode shows superior results for the AEMFC compared to our earlier results. As for the two-stage fuel cell system, it increased the average electric power (mWh) and SPE when compared to single fuel cell systems except when the higher selective anode catalyst (Pt) was used in the first fuel cell prior to the fuel cell in the second fuel cell containing the lower selective anode catalyst (PtNi).
|
|
| 5. |
- Kanninen, Petri, et al.
(författare)
-
Activation of commercial Pt/C catalyst toward glucose electro-oxidation by irreversible Bi adsorption
- 2018
-
Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier. - 2056-9386. ; 27:5, s. 1446-1452
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of irreversibly adsorbed Bi on commercial Pt/C catalyst toward glucose electro-oxidation reaction (GOR) in different electrolytes (acidic, neutral, alkaline) is studied. Bi is successfully deposited on Pt/C from Bi3+ containing acidic solution from 0 to 90% coverage degree. The stability of the Bi layer in acid and alkaline corresponded to previous studies and started to dissolve at 0.7 V and 0.8 V versus reversible hydrogen electrode (RHE), respectively. However, in neutral phosphate buffer the layer showed remarkable stability to at least 1.2 V versus RHE. Bi modification at low (20%) and high (80%) coverage showed the highest increase in the activity of Pt/C toward GOR by a factor up to 7 due to the increased poisoning resistance of the modified catalyst. The effect of poisoning was especially reduced at high Bi coverage (80%), which shows that adsorbate blocked by Bi through the third-body effect is effective. Finally, with or without Bi modification GOR on Pt/C was most active in alkaline conditions.
|
|
| 6. |
- Kortsdottir, Katrin, 1979-
(författare)
-
The Impact of Hydrocarbon and Carbon Oxide Impuritiesin the Hydrogen Feed of a PEM Fuel Cell
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The proton exchange membrane fuel cell generates electricity from hydrogen and oxygen (from air) through electrocatalytic reactions in an electrochemical cell. The Pt/C catalyst, commonly used in PEM fuel cells, is very sensitive to impurities that can interact with the active catalyst sites and limit fuel cell performance. Unfortunately, most hydrogen is currently produced from fossil sources, and inevitably contains impurities.The subject of this thesis is the effect of hydrogen impurities on the operation of a PEM fuel cell using a Pt/C anode. The impurities studied are carbon monoxide (CO), carbon dioxide (CO2), and selected hydrocarbons. Particular focus is given to the interaction between the impurities studied and the anode catalyst. The main method used in the study involved performing cyclic voltammetry and mass spectrometry, simultaneously. Other electrochemical techniques are also employed.The results show that all the impurities studied adsorb to some extent on the Pt/C catalyst surface, and require potentials comparable to that of CO oxidation, i.e., about 0.6V, or higher to be removed by oxidation to CO2. For complete oxidation of propene, and toluene, potentials of above 0.8, and 1.0V, respectively, are required. The unsaturated hydrocarbons can be desorbed to some extent by reduction, but oxidation is required for complete removal. Adsorption of ethene, propene, and CO2 is dependent on the presence of adsorbed or gaseous hydrogen. Hydrogen inhibits ethene and propene adsorption, but facilitates CO2 adsorption. Adsorption of methane and propane is very limited and high concentrations of methane cause dilution effects only.The adlayer formed on the Pt/C anode catalyst in the presence of CO2, or moderate amounts of hydrocarbons, is found to be insffuciently complete to notably interfere with the hydrogen oxidation reaction. Higher concentrations of toluene do, however, limit the reaction.
|
|
