Local Charge Density Regulation of NiP2 Nanosheets via Ru Doping for Electrocatalytic Urea Oxidation

The substantial discharge of urea-rich wastewater presents a significant threat to the ecological environment. The electrocatalytic urea oxidation reaction (UOR) represents an efficient and environmentally sustainable approach for urea degradation, with its low thermodynamic potential suggesting considerable potential to supplant the oxygen evolution reaction (OER) in energy-efficient hydrogen production from water electrolysis. Although nickel-based catalysts show considerable promise for UOR, the high energy barrier associated with the formation of Ni 3+ remains an obstacle for the reaction. Here, a Ru-doped NiP 2 nanosheet array (NiP 2 -Ru) catalyst was constructed for UOR. The experimental results indicate that Ru doping modulates the local charge distribution of NiP 2 , thereby increasing the oxidation state of Ni. This modification facilitates the formation of highly active Ni 3+ sites, which substantially enhances the UOR activity of NiP 2 . The NiP 2 -Ru catalyst demonstrates exceptional UOR performance, requiring an overpotential of only 0.95 and 0.99   V to achieve a current density of 10 and 100   mA   cm −2 with a low Tafel slope of 11.27   mV dec –1 , respectively, in a 1   m KOH solution containing 0.33   m urea, which is comparable to the best reported UOR activity. Furthermore, the catalyst exhibits an excellent stability for over 100   h. This research proposes a viable strategy for the design and synthesis of effective UOR electrocatalysts and advocates further exploration of the application of transition metal phosphides in various environmental and energy-related domains.