Data/hora: 27/05/2024 15:04:35

Biblioteca(s): | Embrapa Instrumentação.
Data corrente: | 22/12/1999
Data da última atualização: | 22/12/1999
Autoria: | ASSIS, O. B. G.; CRNKOVIC, F. C.; BERNARDES FILHO, R.; AVACA, L. A.
Afiliação: | EMBRAPA-CNPDIA; USP-IQSC.
Título: | Roughness assessment of Ni-Co spinel type oxide electrode by atomic force microscope.
Ano de publicação: | 1997
Fonte/Imprenta: | In: MEETING OF THE BRAZILIAN SOCIETY FOR ELECTRON MICROSCOPY, 16., 1997, CAXAMBU. Proceedings of the 16. Meeting of the Brazilian Society for Electron Microscopy. Caxambu: Brazilian Society for Electron Microscopy, 1997. p. 76-77. Acta Microscopica, v.6, Supplement A, September 1997.
Idioma: | Inglês
Conteúdo: | Spinel type oxides such as NiCO2O4, are of great interest for application in electrochemical industry specially as anodes for water electrolysis and the oxygen evolution reaction. The large electrocatalytic activity of these types of materials under potentiodynamic conditions results from mechanisms of ionic transference on the solid-liquid interface and are rather dependent on the real electrode area. An increase in the geometric surface outcome an increase in the current density enhancing thus the electrolysis reaction. The roughness factor in voltametric condition, is deduced from the electrochemical peak currents normalized with respect to a flat reference electrode, as the relation (Ic(flat/Ic(rough)). Since the electrolyte medium offers differences in the ionic conductivity, and bubbles can be generate and keep attached to the electrode's surface crevices, the estimation by this method is limited and validated only in a short range of experimental conditions.An reliable way to state relative irregularities in solid surfaces is by the generation of scanning atomic force microscope (AFM) images. The AFM allows the evaluation of the surface by a direct topography assessment. In this work, the roughness of a Ni-Co base oxide electrode is evaluated as an example of the potential of the atomic force microscopy in revealing subtle details of surface. This technique when associated with appropriated software analysis, presents large advantage over chemical or two-dimensional microscopy techniques. In Figure 1 is presented a random 50 x 50 micrometers area from a central region of a NiCo2O4 polished, flat like electrode, prepared as describe in reference 3. Three intermediates analytical lines at (A), (B) and (C) were traced and the surface profiles plotted in Figure 2. These cross-sectional plots presents the actual topography along the particular line scanned. As it is possible to compare, the topographies lines show shallow corrugation and blunts increasing from the top to the bottom regions of the figure. The standard roughness values presented in the boxes of Figure 2, means the linear measurements of the lines correspondent to the surface's lenghts, since the projected straight line are 50 micrometers lenght it is possible to evaluate a proportional increase of area from a flat surface. An other possible tools is the overall roughness mapping on the figure. That is performed by processing the data from the total of the lines scanned. For the scanned regions, the RMS area is found to be 1.87 times the projected one. In Figure 3 a three dimensional projection of the region is plotted.
Palavras-Chave: | AFM; Agricultural instrumentation; Congressos; EMBRAPA-CNPDIA; Instrumentacao agropecuaria; Microscopia de forca atomica; Technique; Tecnica.
Thesaurus Nal: | atomic force microscopy.
Categoria do assunto: | --
Registro original: | Embrapa Instrumentação (CNPDIA)
Exemplares: | CNPDIA - (5644-1) - UPC - SP - -- - PROCI-97.00030 -  - 1997.00030 - DIS