Estudo da preparação de eletrocatalisadores Pt-Sn/C por meio da deposição superficial de Pt sobre Sn/C utilizando diferentes metodologias para aplicação na oxidação eletroquímica do etanol

Abstract

We present a study of the achievement of Pt-Sn/C electrocatalysts from the deposition of Pt on Sn/C surface using different methodologies. The Sn/C support were obtained by reduction method with sodium borohydride (BH) and by the alcohol reduction method (MRA). Pt deposition was carried out by the galvanic exchange process and by using reducing BH and MRA methods. The materials were characterized using energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray linear scan (EDXline scan), cyclic voltammetry (VC) and CO stripping and tested by electrochemical oxidation of ethanol. A comparison between MRA and BH method showed the presence of Sn metal phase in the X-ray diffractogram Sn/C using the first method while the second lead to the formation of the SnO2 phase. The obtained material resulted by deposition process more active than the Sn holder (BH)/C but less active than commercial catalyst PtSn/C BASF. The materials result to be more active than the commercial catalyst. The Pt deposition process using BH method on Sn (BH)/C support led to catalysts with lower performance to the commercial catalyst because, in this case, the deposition occurs of Pt preferably on Sn metal nanoparticles, making the surface of the catalyst rich in Pt. Studies by transmission electron microscopy-EDX-line-scan showed that this material had the most even distribution of Pt and Sn sites on the catalyst surface. In this work, we obtained electrocatalyst by Pt deposition on Sn/C's surface, with higher activity than the Commercial PtSn/C catalyst and verified that the materials obtained in a single step process by co-reduction are the ones with higher activity.