Célula a combustível microfluídica de papel alimentada por etilenoglicol: O uso de quantidades reduzidas de Pt no ânodo na busca por um dispositivo descartável

Abstract

Paper-based microfluidic fuel cells (PµFCs) are devices capable of generating energy by exploiting the capillarity of paper, enabling fluid flow without the need for external pumping or membranes. These devices are intended to be disposable, low-cost, and capable of providing sufficient energy to power small electronics. The main challenge lies in designing sustainable and efficient PµFCs while minimizing the use of platinum, a costly material that is toxic in high quantities. To maintain efficiency while reducing Pt usage in the cell, a controlled deposition strategy was adopted using the sputtering technique. In this work, we present a PµFC equipped with anodes composed of carbon paper (CP) modified with reduced amounts of Pt deposited via sputtering and a metal-free CP cathode, powered by ethylene glycol, a biomass-derived fuel. The cell was designed for a mixed medium, where ethylene glycol is electro-oxidized in an alkaline medium, while Na₂S₂O₈ is reduced in an acidic medium, allowing half-cell reactions to be independently optimized. The PµFC exhibited a maximum current density of 101.80 mA cm⁻² and a power density of 9.75 mW cm⁻², positioning it among the highest reported for paper-based microfluidic fuel cells powered by alcohols. Half-cell measurements revealed that electrodes prepared by sputtering with reduced Pt content in CP achieved higher maximum currents and lower onset potentials, indicating enhanced efficiency. Stability tests showed a decline in electrode performance over cycles due to CO poisoning, although an improvement in reaction kinetics was observed with an increasing number of cycles. Comparatively, the Pt/CP-40 and Pt/CP-60 electrodes outperformed Pt/C/CP in terms of power density. The anodes with lower Pt content demonstrated greater efficiency in terms of power density and mass-specific current, supporting the development of more sustainable and cost-effective devices. These findings promote advancements in clean energy technologies and broaden the applicability of paper-based microfluidic fuel cells.