FeNi supported on carbon sponge for efficient urea oxidation in direct urea fuel cell

The direct urea fuel cell (DUFC) is a power generation equipment with urea-rich wastewater or urine as fuel source. It has the unique ability to purify sewage while simultaneously generating electricity, making it a highly efficient and environmentally friendly option. In this paper, pomegranate seed-like Ni nano-blocks and Fe nanosheets were synthesized by electrodeposition and chemical reduction and attached to the carbonized melamine sponge matrix. The N-doped carbon sponge (NCS) provided a large number of polyhedral holes, which allowed for efficient gas escape through channels. The combination of Fe reduces the initial urea oxidation potential, reaction activation energy and reaction resistance. The synthesized FeNi supported on N-doped carbon sponge composite (FeNi@NCS) has a catalytic current density of 625 mA cm-2 and a Tafel slope of 42.51 mV dec-1 for urea electrooxidation reaction (UOR). Assembling the direct urine-hydrogen peroxide fuel cell (DUrHPFC) resulted in the highest performance output. The open circuit voltage (OCV) was 0.98 V, and the peak power density reached 9.61 mW cm-2. The results show that the prepared catalyst provides an opportunity to solve the problems that hinder the development of urea green cycle at present.