| Autor: |
Huang J; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Marshall CR; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Ojha K; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Shen M; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Golledge S; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Kadota K; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., McKenzie J; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Fabrizio K; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Mitchell JB; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Khaliq F; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Davenport AM; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., LeRoy MA; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Mapile AN; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Debela TT; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Twight LP; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Hendon CH; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States., Brozek CK; Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States. |
| Abstrakt: |
Redox intercalation involves coupled ion-electron motion within host materials, finding extensive application in energy storage, electrocatalysis, sensing, and optoelectronics. Monodisperse MOF nanocrystals, compared to their bulk phases, exhibit accelerated mass transport kinetics that promote redox intercalation inside nanoconfined pores. However, nanosizing MOFs significantly increases their external surface-to-volume ratios, making the intercalation redox chemistry into MOF nanocrystals difficult to understand due to the challenge of differentiating redox sites at the exterior of MOF particles from the internal nanoconfined pores. Here, we report that Fe(1,2,3-triazolate) 2 possesses an intercalation-based redox process shifted ca. 1.2 V from redox at the particle surface. Such distinct chemical environments do not appear in idealized MOF crystal structures but become magnified in MOF nanoparticles. Quartz crystal microbalance and time-of-flight secondary ion mass spectrometry combined with electrochemical studies identify the existence of a distinct and highly reversible Fe 2+ /Fe 3+ redox event occurring within the MOF interior. Systematic manipulation of experimental parameters (e.g., film thickness, electrolyte species, solvent, and reaction temperature) reveals that this feature arises from the nanoconfined (4.54 Å) pores gating the entry of charge-compensating anions. Due to the requirement for full desolvation and reorganization of electrolyte outside the MOF particle, the anion-coupled oxidation of internal Fe 2+ sites involves a giant redox entropy change (i.e., 164 J K -1 mol -1 ). Taken together, this study establishes a microscopic picture of ion-intercalation redox chemistry in nanoconfined environments and demonstrates the synthetic possibility of tuning electrode potentials by over a volt, with profound implications for energy capture and storage technologies. |
