Outstanding performance of direct urea/hydrogen peroxide fuel cell based on precious metal-free catalyst electrodes

Abstract

Direct urea/hydrogen peroxide fuel cells (DUHP-FCs) can produce electrical energy by recycling urea-rich wastewater. This study expands the commerciality of DUHP-FC by removing precious metals from their design. Nickel nanorod/nickel foam (NNR/NF) was fabricated using hydrothermal treatment to be used as the anode, and Prussian blue coating was deposited by potentiostatic electrodeposition onto hydrophilic carbon felt at the cathode (PB/CF). The anode exhibited a 7-folds higher current density than bare NF at 0–2 M urea, and lower charge transfer resistance. The cathode reported a high H2O2 reduction current. In addition, fuel cell tests indicated current density dependency on H2O2 concentration and cell voltage dependency on KCl concentration. A competitive maximum power density of 10.6 mW cm−2 was achieved at 0.98 open circuit voltage and 45 mA cm−2 maximum current density, in 0.33 M urea vs 2 M KCl and 2 M H2O2, exclusively via diffusive mass transfer. These findings indicate the practical application of DUHP-FC on a large scale.