Influence of Composition of Ti/SnO<sub>2</sub>-Sb<sub>2</sub>O<sub>5</sub> on the Kinetics of Electro-Oxidation
Notice bibliographique
Résumé
The Ti/SnO 2 -Sb 2 O 5 anode is a promising material for the anodic oxidation of organic compounds for the application of wastewater treatment. The material consists of a thin film of Sb-doped SnO 2 on the titanium substrate. The influence of Sb doping on the conductivity of SnO 2 thin films has been well documented, but its effect on the catalysis of electro-oxidation remains largely unknown. The current investigation presents a systematic study addressing this knowledge gap. A series of Ti/SnO 2 -Sb 2 O 5 anodes were prepared using thermal deposition and electro-deposition. These films contained a wide range of doping levels, expressed as atomic fraction Sb/(Sn+Sb), essentially from SnO 2 dominant to SbO x dominant. The surface composition of deposited coatings was determined by X-ray photoelectron spectroscopy. The electrochemical activities of the electrodes were evaluated through the use of polarization scans performed in a simulated wastewater system containing oxalic acid as an organic analog target for destruction. All electrodes exhibited Tafel behavior. Different anodes were compared based on their activity, defined as the anodic current at 1.7V SHE normalized by the surface roughness of the electrode. Electrochemical impedance spectroscopy was used to estimate the effective surface area, by means of effective double-layer capacitance. Scanning voltammetry in 0.01mol/L oxalic acid showed Tafel slopes varying between 180~250mV/dec (Figure 1). Some samples with very high and low doping levels of antimony showed even higher Tafel slopes. The above findings were related to the conductivity of the doped films. Herrmann et al. , reported that the conductivity of the mixed antimony-tin oxide was highly dependent on the level of Sb doping in the film 1 . According to their study, the SnO 2 -Sb 2 O 5 mixed oxide was highly conductive with Sb doping level between 1.7% and 40%. Oxides with doping levels outside this range exhibited a drop in conductivity by three orders of magnitude. In the present investigation, the uncompensated resistance of the coating films in the electrodes can results in abnormally high Tafel slopes as shown in Figure 1. The activities of the anodes were compared at 1.7V SHE . The current levels were normalized to the double-layer capacitance of the electrode and plotted against the doping level as shown in Figure 2. A volcano curve is evident from the figure, which suggested that the electrode had an optimum doping level at about 2% Sb doping. This level of doping was different from the composition corresponding to the highest conductivity that was identified by Herrmann et al. 1 . The beneficial increase in the performance of the electrode at this doping level of could be related to the surface arrangement of Sb atoms in the SnO 2 lattice. Ongoing work is being conducted to characterize the surface features of the Sb-doped SnO 2 materials. Reference: 1. J-M. J. Herrmann, J-L. Portefaix, M. Forissier, F. Figueras, P. Pichat, Electrical Behavior of Powdered Tin-Antimony Mixed Oxide Catalysts. J. Chem. Soc. Farad. Trans. I, 75, 1346 (1979). Figure 1
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».