(Energy Technology Division Graduate Student Award) Designing Polyoxometalate-Carbon Hybrid Materials for Supercapacitor Electrodes
Notice bibliographique
Résumé
This talk will provide an overview of our recent work in the development of supercapacitor electrode materials based on the modification of carbon substrates (MWCNTs and Activated Carbons) with custom designed polyoxometalate (POM) molecular coatings. POMs undergo fast reversible multi-electron transfer reactions, an ideal characteristic for electrochemical energy storage. When immobilized on a carbon substrate these POM molecules provide enhanced charge storage capacity due to their faradaic reactions, while the carbon material contributes mechanical support, improved conductivity, and physical capacitive effects. Different POM molecules such as PMo 12 O 40 3- (PMo 12 ) and PW 12 O 40 3- (PW 12 ) demonstrate characteristic electrochemical activity related to their chemical composition. However, we have discovered that when these molecules are combined in aqueous solutions they do not just physically mix, but instead react spontaneously to form PMo 12-x W x mixed addenda chemistries with unique electrochemical properties different from that of individual PMo 12 or PW 12 . We have also demonstrated that this mixture behaviour can be extended to additional POM combinations such as SiMo 12 O 40 4- (SiMo 12 ) and SiW 12 O 40 4- (SiW 12 ). These novel POM combinations have electrochemical properties that can be easily tuned based upon the compositions of the mixtures. This control over POM redox behavior can be used along with layer-by-layer (LbL) deposition to design molecular coatings that demonstrate desired pseudocapacitive characteristics. The best performance was achieved with a coating that superimposed a 3:1 PMo 12 O 40 3− -PW 12 O 40 3− mixed layer on a 1:1 GeMo 12 O 40 4− -SiMo 12 O 40 4− mixed layer, which resulted in a 5X capacitance enhancement over unmodified MWCNT. This dual layer electrode also demonstrated a close to rectangular CV profile due to the overlapping redox features of the POM combination (Figure 1). In addition to our work on the POM active layers, our current research on the development of alterative carbon substrates will also be discussed. While MWCNT is an effective substrate for POM modification, we have recently focused on the fabrication of less expensive activated carbon materials based on waste biomass precursors. We have developed a nanostructured carbon material based on corn-cob biomass via a simple high temperature exfoliation procedure. This exfoliated corn biochar had excellent energy storage performance, demonstrating a capacitance over 100 times higher than natural corn biochar produced without exfoliation treatment. Additionally, high surface area activated carbons from pine cone biomass were synthesized via a two-step carbonization and KOH activation method. These high surface area substrates result in carbon-POM hybrids with further enhanced specific capacitance compared to nanocarbon based materials. The capacitive performance of these different carbon-POM composites will be compared along with a discussion of how our approach can be leveraged to design the optimal hybrid material for different energy storage applications. Figure 1
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Comment cette classification a été obtenuedéplier
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 | 0,002 | 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 ».