Coupling Dual-phased nickel selenides with N-doped carbon enables efficient urea electrocatalytic oxidation

Electrochemical urea oxidation reaction (UOR) is urgently in demand for diverse energy conversion and storage device coupled with pollution treatment because of its favorable thermodynamic potential (0.37 V vs RHE) and wide distribution nature of urea, but simultaneously gravely limited by the sluggish reaction dynamics and poisoning of catalyst. Herein, dual-phased Ni_0.85Se/NiSe₂ coupling with N doped carbon (Ni_0.85Se/NiSe₂@NC-2) in situ is prepared by a solvothermal-selenization pathway. Benefiting from the collective promotion of the dual-phased composition and the NC support, Ni_0.85Se/NiSe₂@NC provides abundant active sites, enhanced electrical conductivity. It delivers a current density of 252 mA cm^-2 at 1.6 V vs RHE with a small Tafel slop of 64.4 mV dec^-1 and gets a lower reaction barrier. Moreover, it requires a cell voltage of 1.46 V to approach 50 mA cm^-2, about 250 mV less than that of water electrolysis, confirming the less energy consumption. Notably, the N doped carbon protects Ni_0.85Se/NiSe₂ nanocrystals from aggregation leading to a faster CO₂ desorption from Ni sites, which endow the Ni_0.85Se/NiSe₂@NC-2 a much better working stability. The direct urea hydrogen peroxide fuel cell (DUHPFC) achieves a maximum power density of 9.09 mW cm^-2 at 20 °C. This work extends highly efficient dual-phased structure loading in NC catalysts system for urea-assisted energy conversion.