Balancing the competitive adsorption of urea and OH− over V-NiCo@NC for enhancing urea electrolysis at high current density

Urea is a common component present in both biological waste and water pollutants. Using it as an electrolyte substrate to replace the oxygen evolution reaction (OER) on the anode to assist hydrogen production is thermodynamically favorable and economically attractive. However, at high current densities (e.g., greater than 500 mA cm −2 ), the competitive adsorption of urea and OH − significantly limits the activity of the urea oxidation reaction (UOR). To overcome this challenge, this work designed and developed a catalyst consisting of a V-doped NiCo alloy, which is enclosed in an N-doped carbon layer. According to spectral characterization and density functional theory (DFT), the synergistic interaction between the N-doped carbon layer and V enhances the electron enrichment from the bulk to the surface. Meanwhile, the highly electronegative nitrogen atoms simultaneously regulate the local charge distribution of the carbon layer. This guarantees the optimal binding strength between reactants (urea and OH − ) and active sites. Consequently, V-NiCo@NC exhibits excellent urea oxidation performance ( E 10/1000  = 1.27/1.43 V RHE ). Additionally, the introduction of the N-doped carbon layer significantly improves the long-term durability of the catalyst, it can run steadily for 100 h at 1000 mA cm −2 . This work provides an approach for designing efficient UOR catalyst materials and offers insights for optimizing catalytic performance by balancing competing adsorption.