Electron Transfer at Oxide Surfaces. The MgO Paradigm: from Defects to Ultrathin Films

2012 ◽  
Vol 113 (6) ◽  
pp. 4035-4072 ◽  
Author(s):  
Gianfranco Pacchioni ◽  
Hajo Freund
Keyword(s):  
Electron Transfer ◽  
Ultrathin Films ◽  
Oxide Surfaces

scholarly journals On the Mechanism of Carbon Dioxide Reduction on Sn-Based Electrodes: Insights into the Role of Oxide Surfaces

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 636 ◽  
Author(s):  
Giane B. Damas ◽  
Caetano R. Miranda ◽  
Ricardo Sgarbi ◽  
James M. Portela ◽  
Mariana R. Camilo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Electron Transfer ◽  
Formic Acid ◽  
Oxide Layer ◽  
Co2 Reduction ◽  
Carbon Dioxide Reduction ◽  
Oxide Surfaces ◽  
In Situ Conditions

The electrochemical reduction of carbon dioxide into carbon monoxide, hydrocarbons and formic acid has offered an interesting alternative for a sustainable energy scenario. In this context, Sn-based electrodes have attracted a great deal of attention because they present low price and toxicity, as well as high faradaic efficiency (FE) for formic acid (or formate) production at relatively low overpotentials. In this work, we investigate the role of tin oxide surfaces on Sn-based electrodes for carbon dioxide reduction into formate by means of experimental and theoretical methods. Cyclic voltammetry measurements of Sn-based electrodes, with different initial degree of oxidation, result in similar onset potentials for the CO2 reduction to formate, ca. −0.8 to −0.9 V vs. reversible hydrogen electrode (RHE), with faradaic efficiencies of about 90–92% at −1.25 V (vs. RHE). These results indicate that under in-situ conditions, the electrode surfaces might converge to very similar structures, with partially reduced or metastable Sn oxides, which serve as active sites for the CO2 reduction. The high faradaic efficiencies of the Sn electrodes brought by the etching/air exposition procedure is ascribed to the formation of a Sn oxide layer with optimized thickness, which is persistent under in situ conditions. Such oxide layer enables the CO2 “activation”, also favoring the electron transfer during the CO2 reduction reaction due to its better electric conductivity. In order to elucidate the reaction mechanism, we have performed density functional theory calculations on different slab models starting from the bulk SnO and Sn6O4(OH)4 compounds with focus on the formation of -OH groups at the water-oxide interface. We have found that the insertion of CO2 into the Sn-OH bond is thermodynamically favorable, leading to the stabilization of the tin-carbonate species, which is subsequently reduced to produce formic acid through a proton-coupled electron transfer process. The calculated potential for CO2 reduction (E = −1.09 V vs. RHE) displays good agreement with the experimental findings and, therefore, support the CO2 insertion onto Sn-oxide as a plausible mechanism for the CO2 reduction in the potential domain where metastable oxides are still present on the Sn surface. These results not only rationalize a number of literature divergent reports but also provide a guideline for the design of efficient CO2 reduction electrocatalysts.

Mixed Oxide Surfaces:  Ultrathin Films of CaxMg(1-x)O

1998 ◽  
Vol 102 (4) ◽  
pp. 693-700 ◽  
Author(s):  
M. J. Iedema ◽  
N. Kizhakevariam ◽  
J. P. Cowin
Keyword(s):  
Mixed Oxide ◽  
Ultrathin Films ◽  
Oxide Surfaces

ChemInform Abstract: Mixed Oxide Surfaces: Ultrathin Films of CaxMg(1-x)O.

ChemInform ◽  
2010 ◽  
Vol 29 (20) ◽  
pp. no-no
Author(s):  
M. J. IEDEMA ◽  
N. KIZHAKEVARIAM ◽  
J. P. COWIN
Keyword(s):  
Mixed Oxide ◽  
Ultrathin Films ◽  
Oxide Surfaces

Anchoring groups for photocatalytic water oxidation on metal oxide surfaces

2017 ◽  
Vol 46 (20) ◽  
pp. 6099-6110 ◽  
Author(s):  
Kelly L. Materna ◽  
Robert H. Crabtree ◽  
Gary W. Brudvig
Keyword(s):  
Electron Transfer ◽  
Metal Oxide ◽  
Water Oxidation ◽  
Oxide Surfaces ◽  
Water Stability ◽  
Binding Modes ◽  
Metal Oxide Surfaces ◽  
Anchoring Groups

The synthesis, binding modes, water stability, and electron-transfer dynamics are compared for carboxylate, phosphonate, hydroxamate, and silatrane anchoring groups.

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