Banca de QUALIFICAÇÃO: MILENA KOWALCZUK MANOSSO AMORIM
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.STUDENT : MILENA KOWALCZUK MANOSSO AMORIM
DATE: 28/07/2021
LOCAL: Plataforma Google Meet, às 09:00h
TITLE:
Synthesis and characterisation of Metal-Organic Frameworks (MOFs) and MOF-derived ceramic as electrode materials for supercapacitors.
KEY WORDS:
Metal-Organic Frameworks. Oxides. Coin cells. Supercapacitors
PAGES: 67
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:
The way energy is stored has influenced human activities since the beginning of civilization. In the last decades, the concerns about the impacts that fossil fuels have caused on the environment have increased. The use of cleaner and renewable energy sources has been actively encouraged, and electrochemical energy storage is an important part of integrating these renewable sources into the currently available infrastructure. In this work, monometallic manganese and copper MOFs were synthesised through the sonochemical method and doped with cobalt using the wet impregnation technique. Bimetallic MOFs were obtained with well-dispersed Co in the structure, varying from 11.62 to 25.79% in Mn-MOF samples and 1.98 % in the Cu-MOF sample. MOFs were characterised by X-Ray Powder Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, Thermogravimetry Analysis (TGA), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). Manganese based MOF and its oxides were electrochemically characterised by Cyclic Voltammetry (CV) and charging curves. The impregnation process affected the morphology of the pristine MOF particles by introducing cracks and irregularities into their particle surface, but XRD results showed that the original structure was preserved. To obtain the oxides, Mn-MOF was thermolysed for one hour at 600 ºC and 650 ºC, and Mn/Co-MOF was thermolysed for one hour and two hours at 600 ºC and 650 ºC. The presence of Co in the nanoparticles seemed to prevent agglomeration since flattened structures appeared in Mn/Co oxides, differently from the large agglomerates observed in Mn oxides. Mn/Co oxide obtained after thermolysis for two hours at 650 ºC presented well separated and defined sheets with thickness estimated at 104 nm; this structure was not observed for the sample prepared within one hour. The average particle size of Mn-MOF and Mn/Co-MOF were estimated at 1139 and 585 nm, respectively. The oxide obtained from Mn-MOF thermolysed at 600 ºC presented an average particle size of 106 nm, almost three times larger than the 34 nm obtained for Mn/Co-MOF under the same conditions. The average particle size of the oxides obtained at 650 ºC or 600 ºC for 2h was not influenced by the duration of thermolysis, ranging from 46 to 51 nm for all samples. Supercapacitors prototypes were assembled on coin cells, using commercial MnO2, Mn-MOF, Mn/Co-MOF, and derived oxides as electrodes. The charging curves and voltammograms of the devices were analysed, and they showed pseudocapacitance behaviour more accentuated in the first cycles of voltammetry.
BANKING MEMBERS:
Presidente - 2163324 - JOANNA ELZBIETA KULESZA
Interna - 2330165 - MARIA GORETI CARVALHO PEREIRA
Externo à Instituição - RODRIGO DA SILVA VIANA - UFPE
Externa à Instituição - ADRIANA SCOTTON ANTONIO CHINELATTO - UEPG