scholarly journals Pt-Rh Alloy Catalysts for Hydrogen Generation developed by Direct Current/Pulse Method

2021 ◽  
Author(s):  
praveen bm ◽  
Bharath K Devendra ◽  
Tripathi V S ◽  
Nagaraju DH ◽  
Nayana K O
Keyword(s):  
Direct Current ◽  
Hydrogen Generation ◽  
Linear Sweep Voltammetry ◽  
Pulse Method ◽  
Force Microscopy ◽  
Highly Active ◽  
Atomic Force ◽  
Alloy Catalysts ◽  
Alloy Catalyst ◽  
Pc Method

Abstract Highly active Pt-Rh alloy catalyst coatings were developed by direct current (DC) and pulse current (PC) electrodeposition method for efficient hydrogen evolution reaction (HER) catalysts. The coatings were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) linear sweep voltammetry (LSV) studies. Pt-Rh alloy catalyst coatings showed almost similar behavior as pure platinum metal.The Pt-Rh coating were obtained by PC method showed low over potentialfor HER. Very low slope of 41.2 mV/dec is obtained represents the Volmer-Tafel mechanistic path way for HER process. Chronopotentiometry was conducted and amount of hydrogen collected during these experiments was 24 ml for PC method 75% duty cycle sample.

OBSERVATION OF DIRECT-CURRENT-INDUCED STEP BENDING PATTERNS ON Si(001)

2000 ◽  
Vol 07 (05n06) ◽  
pp. 577-582 ◽  
Author(s):  
J.-F. NIELSEN ◽  
J. P. PELZ ◽  
M. S. PETTERSEN
Keyword(s):  
Atomic Force Microscopy ◽  
Phase Shift ◽  
Optical Microscopy ◽  
Direct Current ◽  
Applied Current ◽  
Force Microscopy ◽  
Atomic Force ◽  
Theoretical Predictions ◽  
Step Density

Atomic force microscopy and optical microscopy were used to observe a novel "step bending" instability on vicinal Si(001) surfaces heated with direct current along a <110> direction. This instability occurs on areas where the applied current is parallel to the average step direction and consists of wavy step undulations with a nonzero phase shift between adjacent steps, consistent with theoretical predictions by Liu et al. [Phys. Rev. Lett.81, 2743 (1998)]. The resulting "bands" of high step density run obliquely to the direction of the applied current. These step patterns were observed on spherically dimpled surfaces, which also exhibit a variety of other electromigration-induced instabilities.

Local piezoelectric and ferroelectric responses in nanotube-patterned thin films of BaTiO3 synthesized hydrothermally at 200 °C

2006 ◽  
Vol 21 (3) ◽  
pp. 547-551 ◽  
Author(s):  
Rosalía Poyato ◽  
Bryan D. Huey ◽  
Nitin P. Padture
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Atomic Force Microscopy ◽  
Direct Current ◽  
Piezoelectric Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Phase Images ◽  
Fabrication Procedure ◽  
Film Substrate

Piezoresponse atomic-force microscopy (PFM) has been used to characterize the local piezoelectric properties of a novel, nanotube-patterned (“honeycomb”) thin film of BaTiO3 on Ti substrate synthesized hydrothermally at 200 °C. PFM amplitude and phase images, prior to the application of any direct current (dc) field, show ring-shaped piezoelectric regions that correspond to the nanostructure of this film. These results show clearly that the as-synthesized nanotube-patterned BaTiO3 thin film is piezoelectric, with a net spontaneous polarization perpendicular to the film–substrate interface. In addition, polarization switching and hysteresis were observed as a function of applied dc field, confirming that this novel fabrication procedure results in unique configurations of BaTiO3 film that are also ferroelectric.

scholarly journals Membranes for Cation Transport Based on Dendronized Poly(Epichlorohydrin-Co-Ethylene Oxide). Part 2: Membrane Characterization and Transport Properties

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3915
Author(s):  
Alireza Zare ◽  
Xavier Montané ◽  
José Antonio Reina ◽  
Marta Giamberini
Keyword(s):  
Transport Properties ◽  
Liquid Crystalline ◽  
Linear Sweep Voltammetry ◽  
Cation Transport ◽  
Side Chain ◽  
Force Microscopy ◽  
Atomic Force ◽  
Membrane Characterization ◽  
Alkaline Cations

In this paper, we report on the preparation and characterization of membranes out of two side-chain liquid crystalline copolymers, dendronized at two different extents (20 and 40%, CP20 and CP40, respectively). The membranes were characterized by atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), contact angle (CA) analysis, and water uptake. Moreover, transport properties were studied by methanol and proton conductivity experiment and by linear sweep voltammetry (LSV). For the sake of comparison, the behavior of the grafted copolymers was compared with the unmodified copolyether CP0 and with Nafion 117. Results demonstrated that in CP20 and CP40, cation transport depends on the presence of defined cationic channels, not affected by water presence; the comparison between LSV experiments performed with different alkaline cations suggests that CP40 possesses channels with larger diameters and better-defined inner structures.

scholarly journals Development of one-dimensional titania nanomaterials

2014 ◽  
Author(s):  
Ναούμ Βαενάς
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Linear Sweep ◽  
One Dimensional ◽  
Force Microscopy ◽  
Photocurrent Spectroscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Dye Solar Cells

Σκοπός αυτής της διδακτορικής διατριβής είναι η ανάπτυξη μονοδιάστατων νανοδομών τιτανίας και εν συνεχεία η εφαρμογή τους στην κατασκευή ευαισθητοποιημένων ηλιακών κελιών (Dye Solar Cells - DSCs). Οι νανοσωλήνες τιτανίας αποτελούν την ιδανική επιλογή για τους στόχους αυτής της έρευνας καθώς: α) μπορούν να προετοιμαστούν εύκολα από την ανοδική οξείδωση ενός φύλλου τιτανίου, β) επιτρέπουν τον εύκολο έλεγχο της μορφολογίας τους μέσω της ηλεκτροχημικής νάνο-μηχανικής, γ) εξασφαλίζουν εξαιρετικές ηλεκτρικές ιδιότητες, όπως κατευθυνόμενη κίνηση των ηλεκτρονίων. Οι νανοσωλήνες τιτανίας χρησιμοποιήθηκαν ως ηλεκτρόδια εργασίας (photo-anodes) στα ευαισθητοποιημένα ηλιακά κελιά που κατασκευάστηκαν στη συνέχεια.Τα μορφολογικά και δομικά χαρακτηριστικά των νανοσωλήνων μελετήθηκαν με τις τεχνικές, της μικροσκοπίας ατομικών δυνάμεων (Atomic Force Microscopy - AFM), της μικροσκοπίας ηλεκτρονικής σάρωσης (Scanning Electron Microscopy - SEM), της μικροσκοπίας ηλεκτρονικής διελεύσεως (Transmission Electron Microscopy - TEM), της φασματοσκοπίας υπεριώδους/ορατού (Ultraviolet–Visible - UV-Vis) και της φασματοσκοπίας Ράμαν (Raman spectroscopy). Επιπλέον η αξιολόγηση και ο χαρακτηρισμός των ηλιακών κελιών πραγματοποιήθηκε με τις μεθόδους, της φασματοσκοπίας ηλεκτροχημικής εμπέδησης (Electrochemical Impedance Spectroscopy - EIS), της φασματοσκοπίας φωτοδυναμικού/φωτορεύματος περιοδικά μεταβαλλόμενης έντασης φωτισμού (Intensity Modulated Photovoltage/ Photocurrent Spectroscopy - IMVS/IMPS) και τελικά οι αποδόσεις των φωτοβολταϊκών εξάχθηκαν από την βολταμετρία φωτορεύματος (Linear Sweep Voltammetry - LSV). Κίνητρα για αυτήν την μελέτη αποτέλεσαν η ανάγκη κατανόησης, των βασικών μηχανισμών ανάπτυξης των νανοσωλήνων τιτανίας καθώς και των αρχών λειτουργίας που διέπουν τα ευαισθητοποιημένα ηλιακά κελιά. Στο πρώτο μέρος αυτής της έρευνας πραγματοποιήθηκαν μερικά προκαταρτικά πειράματα, με σκοπό την βελτίωση της μορφολογίας του χρησιμοποιούμενου υποστρώματος τιτανίου, όπως και των νανοσωλήνων τιτανίας που προέκυψαν. Μόλις οι συνθήκες ανοδίωσης σταθεροποιήθηκαν, υψηλής ομοιογένειας και ποιότητας νανοσωλήνες προετοιμάστηκαν και χρησιμοποιήθηκαν σε ευαισθητοποιημένα ηλιακά κελιά με ικανοποιητική απόδοση. Στην δεύτερη φάση αυτού του έργου, οι δομικές ιδιότητες των νανοσωλήνων μελετήθηκαν , με σκοπό να εξασφαλιστεί η ανεμπόδιστη μεταφορά των ηλεκτρονίων. Συγκεκριμένα η επίδραση της διαδικασίας απόπτυσης των νανοσωλήνων διερευνήθηκε συνάρτηση των ηλεκτρικών χαρακτηριστικών των φωτοβολταϊκών συσκευών που τελικά παράχθηκαν. Στο τρίτο στάδιο της διατριβής, προηγμένες δομές νανοσωλήνων προετοιμάσθηκαν μέσω σύνθετων τρόπων ανοδίωσης. Η ποτενσιοστατική και γαλβανοστατική ανοδίωση συνδυάστηκαν για πρώτη φορά στην βιβλιογραφία και οδήγησαν στην εξέλιξη της μεθόδου της ανοδίωσης. Το τελευταίο μέρος της δουλειάς αφιερώθηκε αποκλείστηκα στην αύξηση της απόδοσης των φωτοβολταϊκών που ενσωμάτωναν φωτοηλεκτροδία νανοσωλήνων, μέσω της χρήσης των πιο σύγχρονων ηλεκτρολυτών και χρωστικών. Το οξειδοαναγωγικό ζεύγος κοβαλτίου διαχύθηκε με ευκολία στους πορώδους νανοσωλήνες και σε συνδυασμό με την οργανική χρωστική D35, οδήγησε σε υψηλές φωτοτάσεις και αποδόσεις.

Oxidation and Corrosion Resistance of Nanocrystalline Copper Deposit Produced by Pulse Electrodeposition

2011 ◽  
Vol 264-265 ◽  
pp. 1519-1525 ◽  
Author(s):  
M. Saremi ◽  
M. Abouie
Keyword(s):  
Corrosion Resistance ◽  
Direct Current ◽  
Copper Deposit ◽  
Pulse Electrodeposition ◽  
Sulfate Electrolyte ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Oxidation And Corrosion

Pulse electrodeposition was used to produce nanocrystalline (nc) copper from copper sulfate electrolyte with saccharin as additive. The grain size of nanocrystalline coatings was determined using x-ray diffraction and atomic force microscopy (AFM) which was about 30 nm. Microcrystalline copper deposits were also produced by direct current electrodeposition processes and compared with pulse plated ones. Corrosion behavior of the coatings was investigated using polarization and Impedance measurements in different solutions. The oxidation test was carried out at 650°C in an electrical furnace. It was demonstrated that the nanocrystalline film was markedly superior to regularly grained films made by direct current (DC) plating; nanocrystalline deposits show higher corrosion resistance and much higher oxidation resistance.

Gold Nanoparticle Aggregates Preparation by (3-aminpopropyl)- Trimethoxysilane for Highly Active SERS Substrates

2012 ◽  
Vol 562-564 ◽  
pp. 94-97
Author(s):  
Min Zhou ◽  
Qiu Mei Ma ◽  
Yan Wei Wang ◽  
Guang Can Yang
Keyword(s):  
Gold Nanoparticle ◽  
Active Surface ◽  
Morphological Properties ◽  
Force Microscopy ◽  
Sers Substrates ◽  
Highly Active ◽  
Atomic Force ◽  
Vis Spectroscopy ◽  
Surface Enhanced Raman ◽  
Nanoparticle Aggregates

A simple preparation method of gold nanoparticle aggregates for highly active surface enhanced Raman scattering (SERS) substrates is developed by adding APS to gold sol under vigorous magnetic stirring. The optical and morphological properties of these aggregates are examined by UV-vis spectroscopy and atomic force microscopy. It is found that the SERS activity of the new synthesized gold nanoparticle aggregates is about 200 higher than that of single gold nanoparticles with Rhodamine 6G(R6G) probe.

scholarly journals An Electrochemical Route for Hot Alkaline Blackening of Steel: A Nitrite Free Approach

Surfaces ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 216-228 ◽  
Author(s):  
Maximilian Eckl ◽  
Steve Zaubitzer ◽  
Carsten Köntje ◽  
Attila Farkas ◽  
Ludwig Kibler ◽  
...  
Keyword(s):  
Linear Sweep Voltammetry ◽  
Bath Temperature ◽  
Alkaline Solutions ◽  
Linear Sweep ◽  
Dc Voltage ◽  
Force Microscopy ◽  
Protective Layers ◽  
Slope Analysis ◽  
Atomic Force ◽  
Steel Surfaces

Blackening belongs to the predominant technological processes in preserving steel surfaces from corrosion by generating a protective magnetite overlayer. In place of the commonly used dipping-procedure into nitrite-containing blackening baths at boiling temperatures that are far above 100 °C, here we describe a more environmentally friendly electrochemical route that operates at temperatures, even below 100 °C. After an investigation of the electrochemical behavior of steel samples in alkaline solutions at various temperatures, the customarily required bath temperature of more than 130 °C could be significantly lowered to about 80 °C by applying a DC voltage that leads to an electrode potential of 0.5−0.6 V vs. Pt. Thus, it was possible to eliminate the use of hazardous sodium nitrite economically and in an optimum way. Electrochemical quantification of the corrosion behavior of steel surfaces that were in contact with 0.1 M KCl solution was carried out by linear sweep voltammetry and by Tafel slope analysis. When comparing these data, even the corrosion rates of conventional blackened surfaces are of the same magnitude as a blank steel surface. This proves that magnetite overlayers represent rather poor protective layers in the absence of additional sealing. Moreover, cyclic voltammetry (CV), atomic force microscopy (AFM), scanning electron microscopy (SEM) and auger electron spectroscopy (AES) characterized the electrochemically blackened steel surfaces.

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