Banca de DEFESA: SARAH GABRIELA GUIMARÃES DE OLIVEIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : SARAH GABRIELA GUIMARÃES DE OLIVEIRA
DATE: 17/02/2023
TIME: 14:00
LOCAL: Campus 6 - Auditório
TITLE:

STUDY OF ELECTROCHEMICAL COMPATIBILITY OF REDOX ADDITIVES WITH ZIF-67/CABON NANOTUBE ELECTRODES APPLIED IN SUPERCAPACITORS

KEY WORDS:

supercapacitor; metal organic framework; carbon nanotubes; redox electrolyte

PAGES: 62
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

ZIF-67 is a metalorganic network formed by cobalt(II) metallic centers coordinated to four nitrogen atoms of four 2-methylimidazole ligands, in tetrahedral geometry and generating a sodalite structure. Is an attractive material for supercapacitor electrodes due to high specific surface area, high electrochemical stability and an active metal center. However, the low electrical conductivity of pristine ZIF-67 electrodes limits the specific capacitances and rate capabilities. An excellent strategy to increase the specific capacitances is the employ of electrolytes containing species which are capable to transfer electrons to surface electrodes. However, there are no studies that explore the compatibility of different redox species with ZIF-67 electrodes.

In this work, electrodes composed by ZIF-67/multi-walled carbon nanotubes (NTC) were studied with three redox additives in alkaline medium: p-phenylenediamine (PPD), potassium hexacyanoferrate(II) (K₄[Fe(CN)₆]), and potassium iodide (KI). Cyclic voltammetry and charge/discharge galvanostatic measurements were employed to study the charge accumulation mechanism, specific capacitance, efficiency, and life cycle. The electrochemical results reveal that a little extension of redox reactions of iodine species on the electrode of ZIF-67/NTC. On the other side, redox additive with positive formal potentials (K₄[Fe(CN)₆]) is beneficial for boosting  the capacitance (747.1 F g^–1 at 5.0 A g^–1). With PPD, was also beneficial (148.0 F g^–1 at 5.0 A g^–1) and the favorable intermolecular interactions of this redox additive on the ZIF-67/MWCNT electrode surface deliver greater coulombic efficiency and cycling.

COMMITTEE MEMBERS:
Presidente - PAULO FERNANDO RIBEIRO ORTEGA
Interna - RAQUEL VIEIRA MAMBRINI
Interno - JOAO PAULO CAMPOS TRIGUEIRO
Externo à Instituição - TULIO MATENCIO - UFMG
Externo à Instituição - RODRIGO LASSAROTE LAVALL