scholarly journals In situ thermal preparation of oxide surfaces

APL Materials ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 071112 ◽  
Author(s):  
Wolfgang Braun ◽  
Maren Jäger ◽  
Gennadii Laskin ◽  
Prosper Ngabonziza ◽  
Wolfgang Voesch ◽  
...  
Keyword(s):  
Oxide Surfaces ◽  
Thermal Preparation

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.

scholarly journals Independence of surface morphology and reconstruction during the thermal preparation of perovskite oxide surfaces

2018 ◽  
Vol 112 (11) ◽  
pp. 111601 ◽  
Author(s):  
Maren Jäger ◽  
Ali Teker ◽  
Jochen Mannhart ◽  
Wolfgang Braun
Keyword(s):  
Surface Morphology ◽  
Perovskite Oxide ◽  
Oxide Surfaces ◽  
Thermal Preparation

scholarly journals The Environmental Photochemistry of Oxide Surfaces and the Nature of Frozen Salt Solutions: A New in Situ XPS Approach

2016 ◽  
Vol 59 (5-7) ◽  
pp. 591-604 ◽  
Author(s):  
Fabrizio Orlando ◽  
Astrid Waldner ◽  
Thorsten Bartels-Rausch ◽  
Mario Birrer ◽  
Shunsuke Kato ◽  
...  
Keyword(s):  
Oxide Surfaces ◽  
Salt Solutions ◽  
In Situ Xps ◽  
Environmental Photochemistry
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