Obtaining SnO₂@Pt/C, Ni@Pt/C and NiSn@Pt/C for application in the electrocatalyst of oxygen reduction reaction

Recently, the use of Pt-based nanomaterials with core-shell structure as catalysts for oxygen reduction reaction (ORR) has been demonstrated as a promising alternative. The aim of this work was to obtain nanostructures composed of Ni, Sn and Pt, supported on carbon powder (20 % of metallic charge), to be applied in the ORR catalysis. The XRD, SEM, EDX and cyclic voltammetric analyzes showed that the catalysts synthesized by sequential reduction of their precursors had a core-shell structure, i.e., SnO₂, Ni and Ni-Sn nuclei surrounded by Pt (SnO₂@Pt/C, Ni@Pt/C and NiSn@Pt/C, respectively). Rotating disk electrode analyzes showed that the highest catalytic activity was attributed to NiSn@Pt/C, 82 % higher than the commercial Pt-ETEK catalyst. Considering the activity against ORR in the presence of methanol, SnO₂@Pt/C, Ni@Pt/C and NiSn@Pt/C presented higher tolerance to alcohol compared to Pt/C, mainly in low overpotentials, and NiSn@Pt/C continued to exhibit higher activity relative to the other catalysts and Pt-ETEK (approximately four times greater than the commercial catalyst). In this way, it is observed that especially NiSn@Pt/C presented as an interesting alternative for ORR catalysis in both PEMFCs and DMFCs. (author)