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Influence of different carbon and SnO2 ratios on the activity of PtIr/C (SnO2)1 catalysts toward methanol oxidation

2022; Elsevier BV; Volume: 923; Linguagem: Inglês

10.1016/j.jelechem.2022.116793

1873-2569

Jamylle Yanka Cruz Ribeiro, Alisson Vidal dos Anjos, Edmundo Sebadelhe Valério Neto, Stephanie Soares Aristides, Giancarlo R. Salazar‐Banda, Katlin Ivon Barrios Eguiluz,

Advanced battery technologies research

PtIr nanowires (NWs) with a fixed ratio of 90% Pt and 10% Ir were supported in mixtures of Vulcan XC-72 R carbon and tin oxide (SnO2) in the proportions of 50:50, 40:60, 30:70, 20:80, and 10:90 of carbon and SnO2. We successfully synthesized PtIr NWs by chemical reduction of the metallic precursors with formic acid and tested them toward methanol electro-oxidation in acidic media. Neither surfactants nor templates were used during the syntheses. The electrochemical study was conducted by CO-stripping, cyclic voltammetry, chronoamperometry, and steady-state polarization curves. The PtIr NWs have a higher affinity to be anchored onto the carbon support than on SnO2, resulting in different distribution and agglomeration of the NWs that thereby has substantial consequences on the catalytic activity of the composites. The PtIr/C0.4(SnO2)0.6 catalytic composite exhibited the highest activity toward methanol oxidation. The high catalytic performance displayed by the PtIr/C0.4(SnO2)0.6 composite results from the synergy between C and SnO2 as supports (specifically in this proportion), Ir as the co-catalyst, and the morphology of the nanowires. Therefore, these combined effects result in greater mobility of OHads and COads, facilitating the CO removal from the catalyst surface and allowing better methanol adsorption for further oxidation. The PtIr/C0.4(SnO2)0.6 catalyst also showed the lowest resistance to charge transfer compared with the other binary catalysts. Thus, the use of SnO2 + C as supports and PtIr nanocatalysts with NW morphology results in highly active materials toward methanol oxidation, which are promising to compose anodes for direct methanol fuel cells.