scholarly journals Spillover Phenomena and Its Striking Impacts in Electrocatalysis for Hydrogen and Oxygen Electrode Reactions

2011 ◽  
Vol 2011 ◽  
pp. 1-22 ◽  
Author(s):  
Georgios D. Papakonstantinou ◽  
Jelena M. Jaksic ◽  
Diamantoula Labou ◽  
Angeliki Siokou ◽  
Milan M. Jaksic
Keyword(s):  
Sol Gel ◽  
Mixed Valence ◽  
Spillover Effect ◽  
Oxygen Electrode ◽  
Dissociative Adsorption ◽  
Theory And Practice ◽  
Membrane Properties ◽  
Hydrogen Electrode ◽  
Electrode Reactions ◽  
Metal Support Interaction

The core subject of the present paper represents the interrelated spillover (effusion) phenomena both of the primary oxide and the H-adatoms, their theory and practice, causes, appearances and consequences, and evidences of existence, their specific properties, and their alterpolar equilibria and kinetic behavior, structural, and resulting catalytic, and double layer charging features. The aim is to introduce electron conductive and d-d interactive individual and composite (mixed valence) hypo-d-oxide compounds, of increased altervalent capacity, or their suboxides (Magnéli phases), as the interactive catalytic supports and therefrom provide (i) the strong metal-support interaction (SMSI) catalytic effect and (ii) dynamic spillover interactive transfer of primary oxides (M-OH) and free effusional H-adatoms for further electrode reactions and thereby advance the overall electrocatalytic activity. Since hypo-d-oxides feature the exchange membrane properties, the higher the altervalent capacity, the higher the spillover effect. In fact, altervalent hypo-d-oxides impose spontaneous dissociative adsorption of water molecules and then spontaneously pronounced membrane spillover transferring properties instantaneously resulting with corresponding bronze type (Pt/HxWO3) under cathodic and/or its hydrated state (Pt/W(OH)6), responsible for Pt-OH effusion, under anodic polarization, this way establishing instantaneous reversibly revertible alterpolar bronze features (Pt/H0.35WO3 Pt/W(OH)6) and substantially advanced electrocatalytic properties of these composite interactive electrocatalysts. Such nanostructured-type electrocatalysts, even of mixed-valence hypo-d-oxide structures (Pt/H0.35WO3/TiO2/C, Pt/HxNbO3/TiO2/C), have for the first time been synthesized by the sol-gel methods and shown rather high stability, electron conductivity, and nonexchanged initial pure monobronze spillover and catalytic properties. Such a unique electrocatalytic system, as the striking target issue of the present paper, has been shown to be the superior for substantiation of the revertible cell assembly for spontaneous reversible alterpolar interchanges between PEMFC and WE. The main target of the present thorough review study has been to throw some specific insight light on the overall spillover phenomena and their effects in electrocatalysis of oxygen and hydrogen electrode reactions from diverse angles of view and broad contemporary experimental methods and approaches (XPS, FTIR, DRIFT, XRD, potentiodynamic spectra, UHRTEM).

scholarly journals Interactive supported electrocatalysts and spillover effect in electrocatalysis for hydrogen and oxygen electrode reactions

2008 ◽  
Vol 14 (2) ◽  
pp. 119-136 ◽  
Author(s):  
Jelena Jaksic ◽  
Caslav Lacnjevac ◽  
Nedeljko Krstajic ◽  
Milan Jaksic
Keyword(s):  
Spillover Effect ◽  
Oxygen Electrode ◽  
Membrane Properties ◽  
Pt Catalyst ◽  
Hydrogen Atoms ◽  
Charge Capacity ◽  
Electrode Reactions ◽  
Metal Support Interaction ◽  
Doped Titania ◽  
And Shifts

The aim of the present paper has been to introduce the electron conductive and d-d-interactive individual and composite hypo-d-oxides of the increased altervalent capacity, or their suboxides (Magneli phases), as catalytic supports and therefrom provide: (i) The Strong Metal-Support Interaction (SMSI) effect, and (ii) the Dynamic spillover interactive transfer of primary oxides (M-OH) for further electrode reactions, and thereby advance the overall electrocatalytic activity. The d-band has been pointed out as the bonding, adsorptive and catalytic orbital. In the same context, the phenomenon and significance of the d-d-correlations both in heterogeneous catalysis and electrocatalysis are displayed and inferred. Since hypo-d-oxides feature the exchange membrane properties, the higher the altervalent capacity, the higher the spillover effect. Potentiodynamic experiments have shown that the reversible peak of the primary oxide growth on Pt, Ru and Au supported upon hypo-d-oxides and suboxides becomes distinctly increased in the charge capacity and shifts to remarkably more negative potential values, so that it starts even within the range of H-adatoms desorption, while its reduction extends until and merge with the UPD of hydrogen atoms. With wet tungstenia doped titania supported Pt catalyst in membrane cells these peaks dramatically increase in their charge capacity and reversibly become shrunk with a decreased moisture content in the feeding inert gas mixture, and vice versa. Such distinct potentiodynamic scans, in conjunction with some broaden complementary kinetic electrocatalytic improvements rising from the same hypo-d-oxide and/or suboxide interactive support effects, have been proved to be the best and comparable experimental evidence for the spillover effect of primary oxides.

scholarly journals Phenomena and significance of intermediate spillover in electrocatalysis of oxygen and hydrogen electrode reactions

2012 ◽  
Vol 66 (4) ◽  
pp. 425-453 ◽  
Author(s):  
Jelena Jaksic ◽  
Diamantoula Labou ◽  
Georgos Papakonstantinou
Keyword(s):  
Sol Gel ◽  
Aqueous Media ◽  
Mixed Valence ◽  
Intermetallic Phase ◽  
Proton Exchange ◽  
Water Molecules ◽  
Hydrogen Electrode ◽  
Medium Temperature ◽  
Electrode Reactions ◽  
Metal Support Interaction

Altervalent hypo-d-oxides of transition metal series impose spontaneous dissociative adsorption of water molecules and pronounced membrane spillover transferring properties instantaneously resulting with corresponding bronze type (Pt/HxWO3) under cathodic, and/or its hydrated state (Pt/W(OH)6) responsible for the primary oxide (Pt-OH) effusion, under anodic polarization, this way establishing instantaneous reversibly revertible alterpolar bronze features (Pt/H0.35WO3 Pt/W(OH)6), and substantially advanced electrocatalytic properties of these composite interactive electrocatalysts. As the consequence, the new striking and unpredictable prospects both in law and medium temperature proton exchange membrane fuell cell (L&MT PEMFC) and water electrolysis (WE) have been opened by the interactive supported individual (Pt, Pd, Ni) or prevailing hyper-d-electronic nanostructured intermetallic phase clusters (WPt3, NbPt3, HfPd3, ZrNi3), grafted upon and within high altervalent capacity hypo-d-oxides (WO3, Nb2O5, Ta2O5, TiO2) and their proper mixed valence compounds, to create a novel type of alterpolar interchangeable composite electrocatalysts for hydrogen and oxygen electrode reactions. Whereas in aqueous media Pt (Pt/C) features either chemisorbed catalytic surface properties of H-adatoms (Pt-H), or surface oxide (Pt=O), missing any effusion of other interacting species, new generation and selection of composite and interactive strong metal-support interaction (SMSI) electrocatalysts in condensed wet state primarily characterizes interchangeable extremely fast reversible spillover of either H-adatoms, or the primary oxides (Pt-OH, Au-OH), or the invertible bronze type behavior of these significant interactive electrocatalytic ingredients. Such nanostructured type electrocatalysts, even of mixed hypo-d-oxide structure (Pt/H0.35WO3/TiO2/C, Pt/HxNbO3/TiO2/C), have for the first time been synthesized by the sol-gel methods and shown rather high stability, electron conductivity and non-exchanged initial pure mono-bronze spillover and catalytic properties. The underpotential spillover double layer (DL) charging and discharging properties of the primary oxide (M-OH), interrelated with the interactive self-catalytic effect of dipole-oriented water molecules, has also been proved and pointed out as the phenomenological appearance and aspect of the interactive spillover featuring intermediates. In fact, phenomenological aspects of spillover for the main reacting intermediate species in oxygen and hydrogen electrode reactions along with earned and withdrawn theoretical knowledge represent the basic concepts and aims of the present study.

Tailoring the Co4+/Co3+ active sites in single perovskite as a bifunctional catalyst for oxygen electrode reactions "

2021 ◽  
Author(s):  
Song-Jeng Isaac Huang ◽  
Adil Muneeb ◽  
Sabhapathy Palani ◽  
Anjaiah Sheelam ◽  
Bayikadi Khasimsaheb ◽  
...  
Keyword(s):  
Oxygen Evolution Reaction ◽  
Precious Metal ◽  
Active Sites ◽  
Low Cost ◽  
Bifunctional Catalyst ◽  
Oxygen Electrode ◽  
Reduction Reaction ◽  
New Class ◽  
Electrode Reactions ◽  
Energy Conversion Devices

Developing a non-precious metal electrocatalyst for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is desirable for low-cost energy conversion devices. Herein, we designed and developed a new class...

Marking Electrocatalysts on the “Volcanic Belt” of Hydrogen Electrode Reactions

2021 ◽  
Vol 125 (10) ◽  
pp. 5587-5595
Author(s):  
Junwei Li ◽  
Yaxin Ji ◽  
Junxiang Chen ◽  
Zhenhai Wen
Keyword(s):  
Volcanic Belt ◽  
Hydrogen Electrode ◽  
Electrode Reactions

Structural and Electrical Properties of La0.7Ca0.3MnO3 /α-Fe2O3 Composites

2021 ◽  
Vol 317 ◽  
pp. 66-71
Author(s):  
Lik Nguong Lau ◽  
Kean Pah Lim ◽  
Amirah Natasha Ishak ◽  
Mohd Mustafa Awang Kechik ◽  
Soo Kien Chen ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Sol Gel ◽  
Parent Compound ◽  
Mixed Valence ◽  
Space Group ◽  
Colossal Magnetoresistive ◽  
Structural And Electrical Properties ◽  
Modern Application ◽  
Xrd Patterns ◽  
Insulating Phase

Colossal magnetoresistive (CMR) materials have huge potential in modern application and it has been widely used in magnetic sensing industry. From the literature, an incorporation of secondary insulating phase into mixed-valence manganites could improve its extrinsic effect especially low-field magnetoresistance (LFMR). However, nanoparticle addition could lead to substitution and diffusion with its parent compound. In this work, the structural and electrical properties of La0.7Ca0.3MnO3 (LCMO) were investigated by adding the α-Fe2O3 nanoparticle with ratio of 0.00, 0.05, 0.10, 0.15 and 0.20 as the artificial grain boundaries. The LCMO compound has been synthesised using sol-gel route. The samples were chosen to sinter at 800°C to obtain the pure LCMO phase by referring to the thermogravimetric analysis (TGA). The structural properties were investigated by an X-ray diffractometer (XRD) while electrical properties were measured by a four-point probe (4PP) system. XRD patterns showed the coexistence of two phases (LCMO & α-Fe2O3). LCMO crystallised in orthorhombic structure with space group Pnma while α-Fe2O3 exhibited in hexagonal form with space group R-3c. As the content of α-Fe2O3 increases, the resistivity of the samples increases drastically. Nevertheless, the addition of iron oxide has no significant effect on the metal-insulator transition temperature (T­MI). From the XRD and 4PP analysis, it can be deduced that the α-Fe2O3 nanoparticles do not react with LCMO compound and successfully formed the La0.7Ca0.3MnO3 /α-Fe2O3 composites. The resistivity increases when the nano-sized α-Fe2O3 is added into LCMO nanocomposites due to the insulator nature of α-Fe2O3.

Activity of layered swedenborgite structured Y0.8Er0.2BaCo3.2Ga0.8O7+δ for oxygen electrode reactions in at intermediate temperature reversible ceramic cells

2021 ◽  
Vol 9 (1) ◽  
pp. 607-621
Author(s):  
Ji-Seop Shin ◽  
Hyunyoung Park ◽  
Kwangho Park ◽  
Muhammad Saqib ◽  
Minkyeong Jo ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Diffusion Coefficients ◽  
Bulk Diffusion ◽  
Oxygen Electrode ◽  
Intermediate Temperature ◽  
High Chemical ◽  
New Class ◽  
Electrode Reactions ◽  
Low Thermal Expansion

A new class of layered swedenborgite structured Y0.8Er0.2BaCo3.2Ga0.8O7+δ is proposed for oxygen electrode reactions in reversible ceramic cells because of its low thermal expansion and high chemical bulk diffusion coefficients.

Bifunctional atomic iron-based catalyst for oxygen electrode reactions

2019 ◽  
Vol 378 ◽  
pp. 353-362 ◽  
Author(s):  
Lu Bai ◽  
Zhiyao Duan ◽  
Xudong Wen ◽  
Jingqi Guan
Keyword(s):  
Oxygen Electrode ◽  
Electrode Reactions ◽  
Iron Based

Study of Magnetoresistance Effect and Magnetic Properties of La0.67Sr0.33Mn1-xNixO3 (x = 0 and 0.2) Material Prepared by Sol-Gel Method

2019 ◽  
Vol 966 ◽  
pp. 363-369
Author(s):  
Utami Widyaiswari ◽  
Budhy Kurniawan ◽  
Agung Imaduddin ◽  
Isao Watanabe
Keyword(s):  
Magnetic Properties ◽  
Magnetic Measurement ◽  
Sol Gel ◽  
Mixed Valence ◽  
Magnetoresistance Effect ◽  
Metallic Behavior ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Mr Effect

Mixed valence manganite materials have been studied due to their interesting physical properties such as their magnetoresistance (MR) effect. The change of Mn3+/Mn4+ ratio affects the possible bonds between anion and cation and their spin structure that may occur in the samples. The aim of this research is to study the change of magnetoresistance effect and magnetic properties of La0.67Sr0.33MnO3 (LSMO) by doping the Mn site with Ni ion. La0.67Sr0.33Mn1-xNixO3 samples were synthesized by using sol-gel method and characterized by using X-ray diffractometer (XRD) and Energy Dispersive X-ray spectroscopy (EDX) to confirm whether Ni has been doped successfully to the parental compound or not. XRD results showed that the samples have a single phase and Ni peak has been detected in the EDX result of Ni-doped LSMO. Resistivity and magnetic measurement showed that LSMO material has ferromagnetic metallic behavior, while x = 0.20 Ni-doped LSMO sample showed paramagnetic insulator behavior. The absolute value of the MR for un-doped sample is higher than the doped sample when the low field is applied, while under the influence of the high magnetic field, it become smaller than the doped sample.

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