Silicon oxide-protected nickel nanoparticles as biomass-derived catalysts for urea electro-oxidation

The urea electro-oxidation reaction (UOR) is explored as a new technique for energy conversion and the removal of urea via electrochemical means in wastewater. Nickel (Ni) nanoparticles grown on nanosheets were prepared by a facile hydrothermal reaction and a subsequent calcination process of silicon oxide/nitrogen-doped carbon (SiO_x/NC) as the precursor, in which SiO_x/NC with a natural three-dimensional (3D) interconnected structure was obtained from bamboo leaves. The nickel/silicon oxide/nitrogen-doped carbon (Ni/SiO_x/NC, denoted as Y) obtained at 900 °C (Y3), exhibits the most optimal catalytic properties for the UOR with a low potential of 1.384 V vs. RHE at 10 mA cm^-2. The protective role of SiO_x was also explored via the partial etching of SiO_x (Y3-NaOH), and the results show that the overpotential of the curve increased rapidly after long-term test. The findings indicate that full exploitation of the comprehensive advantages of biomass materials is beneficial for alleviating the problems encountered in the development of energy-related technologies.