Direct Formate/Persulfate Microfluidic Fuel Cell with a Catalyst-Free Cathode and High Power Density

Achieving high performance at low cost is crucial and difficult for microfluidic fuel cells (MFCs) as portable power sources. A direct formate microfluidic fuel cell (DFMFC) with a catalyst-free cathode and sodium persulfate as the oxidant is proposed. Due to the strong oxidizing property of sodium persulfate, a carbon paper electrode without a catalyst is used as the cathode directly, greatly reducing the manufacturing cost and ignoring the parasitic current generated from the fuel crossover. In addition, the advantages of the high theoretical potential, environmental friendliness, and good solubility of its reduction products make persulfate an excellent oxidant in MFCs. Moreover, by combining sodium persulfate in an acidic medium and formate in an alkaline medium, a high open-circuit voltage (OCV) of 2 V is yielded. By optimizing the flow rate and concentration of the reactants, the peak power density is 148 mW cm(-2), and the maximum current density is 450 mA cm(-2), which is the highest level among the previously reported similar microfluidic fuel cells. The DFMFC could stably operate during constant voltage discharge. Therefore, it has been demonstrated that a catalyst-free cathode with persulfate as the oxidant is a feasible approach to simultaneously achieve superior cell performance and low cost for MFCs.

Automated summary

A direct formate microfluidic fuel cell (DFMFC) with a catalyst-free cathode and sodium persulfate as the oxidant has been proposed to achieve high performance at low cost. By optimizing the flow rate and concentration of the reactants, the DFMFC achieved a high peak power density and current density, while maintaining stable operation during constant voltage discharge. This study demonstrates that a catalyst-free cathode with persulfate as the oxidant is a feasible approach to simultaneously achieve superior cell performance and low cost for microfluidic fuel cells.