Tolerant Chalcogenide Cathodes of Membraneless Micro Fuel Cells

Abstract

The most critical issues to overcome in micro direct methanol fuel cells (μDMFCs) are the lack of tolerance of the platinum cathode and fuel crossover through the polymer membrane. Thus, two novel tolerant cathodes of a membraneless microlaminar-flow fuel cell (μLFFC), Pt(x)S(y) and CoSe(2), were developed. The multichannel structure of the system was microfabricated in SU-8 polymer. A commercial platinum cathode served for comparison. When using 5 M CH(3)OH as the fuel, maximum power densities of 6.5, 4, and 0.23 mW cm(-2) were achieved for the μLFFC with Pt, Pt(x)S(y), and CoSe(2) cathodes, respectively. The Pt(x)S(y) cathode outperformed Pt in the same fuel cell when using CH(3)OH at concentrations above 10 M. In a situation where fuel crossover is 100 %, that is, mixing the fuel with the reactant, the maximum power density of the micro fuel cell with Pt decreased by 80 %. However, for Pt(x)S(y) this decrease corresponded to 35 % and for CoSe(2) there was no change in performance. This result is the consequence of the high tolerance of the chalcogenide-based cathodes. When using 10 M HCOOH and a palladium-based anode, the μLFFC with a CoSe(2) cathode achieved a maxiumum power density of 1.04 mW cm(-2). This micro fuel cell does not contain either Nafion membrane or platinum. We report, for the first time, the evaluation of Pt(x)S(y)- and CoSe(2)-based cathodes in membraneless micro fuel cells. The results suggest the development of a novel system that is not size restricted and its operation is mainly based on the selectivity of its electrodes.

What Can We Learn in Electrocatalysis, from Nanoparticulated Precious and/or Non-Precious Catalytic Centers Interacting with Their Support?

“…In Figure 46, we can observe how at a fuel concentration of 5 M CH3OH the power density curves reached maximum values of 6.5 mW•cm −2 for Pt, 4 mW•cm −2 for PtxSy and 0.23 mW•cm −2 for CoSe2 when these material were used as cathodes in the micro fuel cell assembly. Moreover, when the micro fuel cell was operated in mixed-reactant mode, the maximum value for the Pt power density decreased by 80%; and 35% for PtxSy; nevertheless, CoSe2 did not present any change in performance [278].…”

“…Coming back to the transition metal chalcogenides and the membraneless fuel cells, two novel catalysts; carbon-supported Pt x S y and CoSe 2 were tested in a novel µLFFC [278]. A schematic image of the fabrication and assembly of the micro fuel cell components is shown in the Figure 45, detailed information about the components and operation can be consulted in reference [278].…”

“…A schematic image of the fabrication and assembly of the micro fuel cell components is shown in the Figure 45, detailed information about the components and operation can be consulted in reference [278]. .…”

“…. Fabrication and operating scheme of the μLFFC (micro-laminar flow fuel cell) [278]. Reprinted with permission from [278].…”

“…This configuration makes easier the fuel delivery and the pumping system reducing the manufacturing costs. Additionally, the crossover issue is no longer a major problem on this kind of micro-devices [278,279].…”