RESUMO Neste trabalho, híbridos Ni/Carbono foram preparados em duas etapas (carbonização hidrotérmica e tratamento térmico a 900 °C sob argônio) a partir de diferentes fontes de carbono: glicose, amido e celulose. Eletrocatalisadores PtRu/C foram preparados pelo método da redução por álcool utilizando os híbridos como suportes. Os materiais foram caracterizados por espectroscopia por energia dispersiva de raios-X (EDX), análise termogravimétrica (TGA), espectroscopia no infravermelho com transformada de Fourier (FTIR), isotermas de B.E.T., difração de raios-X (DRX), microscopia eletrônica de transmissão (TEM) e voltametria cíclica em meio ácido. A eletro-oxidação do metanol foi estudada por cronoamperometria. O eletrocatalisador PtRu/C preparado utilizando o híbrido sintetizado a partir da celulose apresentou uma eletroatividade levemente superior aos demais materiais obtidos.

ABSTRACT In this work, Ni/Carbon hybrids were prepared in two steps (hydrothermal carbonization and thermal treatment at 900 °C under argon atmosphere) using different carbon souces: glucose, starch and cellulose. PtRu/C electrocatalysts were prepared by an alcohol-reduction process using the hybrids as support. The materials were characterized by energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), B.E.T isotherms, X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV) in acidic medium. The electro-oxidation of methanol was studied by chronoamperometry. The PtRu/C electrocatalyst prepared using the hybrid synthesized from cellulose showed an electroactivity slightly superior compared to other obtained materials.

A new mixed material was obtained through the combination of the suspensions of iron oxy-hydroxide and bentonite clay, denoted BFe. Analysis of its structure (XRD, Mossbauer and TGA) and composition (AAS) suggests the maintenance of the layer structure of the clay and an increase in the thermal stability of the BFe. Electrochemical studies performed in different electrolytes show that only in an alkaline medium it is possible to observe the redox peaks relative to the processes involving Fe+2/Fe+3 pair. Tests that evaluated the potential use of the photo-Fenton process showed an efficient degradation process of the dyes in significantly reduced reaction times.