Avaliando a atividade e estabilidade de nanopartículas metálicas frente à eletro-oxidação de metanol utilizando sistema de análise por injeção em batelada.

Fuel cells (FC) have arisen as alternativedevicesto produce energy with low environmental impact, generating energy through two coupled electrochemical reactions.Both cathode and anode are composed ofmetallicnanoparticles(NPs), which work as catalysts. The main challenges to commercialize FCfed by alcohols are the low activity and stability in long-terms of the anode. In this sense, much effort has been spent to develop new active and stable NPs. However, most of the measurementsare carried out in stationary mode and atextremely clean medium (suprapurereagentsand O2-freesolutions), which isa scenariodistant from the uncleanand hydrodynamic conditionsthat real FCare operated.In this sense, we developed analternativemethod to evaluatetheactivity and stability of NPsbased on batchinjection analysis (BIA) system1. Here, a commercial screen-printed electrode modified with NPs is placed on the bottom of a BIA cell and an electronic micropipette is perpendicularly positioned in wall-jet configuration (Fig.1A). The fuel plus electrolyteis successively injected on the working electrodeunder applied potential suitable for methanol electrooxidation,generating ananodic current peakfor each injection(Fig. 1B).The activity is measured by the current density of peak while the catalyst stability is monitoredby the decay of current densityover time(Fig. 1B).We investigated the activity and stability of Pt NPs dispersed on carbon, multi-walled carbon nanotubes and graphene nanoribbons towards methanol electrooxidationin acid medium. The proposedmethod revealsthe behavior of NPs in a more realistic scenariofound in fuel cells (hydrodynamic mass transport and oxygen competition on the anode surface).Moreover, the method is simple,robust, reproducible, inexpensive and portable2