INFLUENCE OF SYNTHESIS TIME IN THE PROPERTIES OF PtRu/CARBON HYBRIDS PREPARED BY HYDROTHERMAL CARBONIZATION METHOD

Abstract

Background: PtRu/C electrocatalysts present good results in methanol electo-oxidation. The activity of these electrocatalysts is strongly dependent on the synthesis method. Additionally, the use of mesoporous carbons or nanostructured carbons increases the performance of electrocatalysts applied in alcohol electro-oxidation. The hydrothermal carbonization method is an alternative to obtain different nanoarchitectures without involving harsh conditions. Aims: Thus, this work aimed to evaluate the influence of synthesis time on the properties of PtRu/Carbon hybrids prepared by the hydrothermal carbonization method. Methods: PtRu/Carbon hybrids were prepared by hydrothermal carbonization at different times of synthesis (6 h and 12 h). It used cellulose as a carbon source and reducing agent and H2PtCl6.6H2O and RuCl3.xH2O as metal sources and catalysts of the carbonization process. The materials were treated at 900 °C and characterized by energy-dispersive X-ray spectroscopy, thermogravimetric analysis, B.E.T isotherms, X-ray diffraction, transmission electron microscope and cyclic voltammetry. The electro-oxidation of methanol was studied by chronoamperometry. Results: The increase in synthesis time from 6 to 12 hours, apparently, resulted in an increase in mean particle size, reduction of mesoporous volume and increase in superficial area and total pore volume. The chronoamperometry of methanol electro-oxidation on these PtRu/Carbon hybrids indicated a higher electroactivity to the material prepared in 6 hours. Discussion: Probably, the higher electroactivity of material prepared in 6 h is associated with smaller particle size, mesoporous structure and surface oxides content. Conclusions: Therefore, it is possible to affirm that the synthesis time is an important parameter that affects the physical-chemical properties of metal/carbon hybrids obtained by the hydrothermal carbonization method.