Intercalated nanosized MO2 (M: Sn, Ce) layers between CNTs and Pt or PtSn nanoparticles catalysts

Abstract

Direct ethanol fuel cells (DEFCs) is receiving enormous attention as alternative electrical energy conversion systems. This paper gives an outline on some recent advances achieved in our laboratory regarding the development of high performing anode for ethanol oxidation. We developed multi-components binderless hierarchically organized layer onto layer nanostructured catalysts comprising a carbon paper (CP, current collector)/carbon nanotubes (CNTs, conductivity enhancer)/catalyst promoter (MOx, M: Sn; Ce)/Pt-based (electrocatalyst). The main focus was how to lower the onset oxidation potential (OOP) of ethanol at Pt₇₅Sn₂₅ catalyst. Towards that aim, metal oxides such as CeO₂ and SnO₂ were sought as catalyst promoters. It has been discovered that intercalating a nanostructured layer of SnO₂ between CNTs and Pt₇₅Sn₂₅ considerably lowered the OOP of ethanol and also increased the specific mass activity (SMA) at low potentials. Indeed, the OOP at the CP/CNT/SnO₂/Pt₇₅Sn₂₅ was 210 mV and 117 mV negative relative to that delivered by CP/CNT/Pt and CP/CNT/Pt₇₅Sn₂₅, respectively confirming by that the promoting effect of SnO₂ of the oxidation of CO at low potentials. The SMA determined at slow potential scan rate of 5 mV/s at 0.4 V vs. Ag/AgCl revealed that CP/CNT/SnO₂/Pt₇₅Sn₂₅ delivered an SMA of 1.2 times higher than that of the CP/CNT/Pt₇₅Sn₂₅ catalyst and 1.5 times greater than the one exhibited by the CP/CNT/CeO₂/Pt₇₅Sn₂₅ catalyst.