CÉLULAS A COMBUSTÍVEL MICROFLUÍDICAS IMPRESSAS EM 3D: UM ESTUDO DE PROTÓTIPOS E DESEMPENHO

Abstract

Microfluidic fuel cells (µFCs) are devices capable of generating power for small to medium-sized electronic equipment. Such devices are constructed using polydimethylsiloxane, and require multiple fabrication steps and manufacturer expertise. There are two main configurations of µFCs: (i) flow-by (or flow-over) and (ii) flow-through, each with its own specificities regarding the electrode positions and how reactants flow through them. Considering the described construction conditions of µFCs, we propose a new methodology that involves fewer development steps, does not require specialized labor, and has a lower cost. We used a 3D printer to construct µFCs in flow-over and flow-through configurations. To establish the concept's viability, we were able to show that 3D-printed devices, in general, are capable of generating power when fueled with biomass derivatives. We demonstrated a 3D-printed µFC fed by glycerol/HClO, which resulted in a power density of 175 mW cm-2 at 0.9V, with an open-circuit potential of 1.8 V. This microfluidic system also enables electrode modification by the use of two methods, in situ and in operando. We modified the device's anode with Bi, and the in situ method showed uniform electrode decoration and also increased the open-circuit potential and power density. Furthermore, this method showed a 72% conversion of glycerol with the detection of glycolate and formate using a glycerol/sodium persulfate-fed system. We developed another device with similar modeling configurations to study different liquid and gaseous oxidants. This device innovation lies in it’s assemble-based model, which allows reusability. This new system recorded higher power densities for the glycerol/HClO configuration using metal-free cathodes, reaching 55.9 mWcm-2 and 1.6 V for open-circuit potential. A 3D-printed microfluidic photo fuel cell (µFC) was also assessed and designed to simultaneously mitigate pollutants while generating energy, indicating its potential for future (photo)electrocatalyst tests. The device recorded a power density of 0.48 mWcm-2 and achieved a conversion rate in the model pollutant through photoelectrochemical processes of 73.6%.