Surface reconstruction of electroless-deposited Ni-Co-P for large-current-density urea-assisted water splitting

Urea electrolysis holds tremendous promise to remediate urea-containing wastewater and produce cost-effective hydrogen. Achieving highly efficient and durable electrocatalysts to drive the anodic urea oxidation reaction (UOR) is paramount to promote its practical applications. Herein, electroless deposition, a scalable, cost-effective, and energy-saving approach, is used to obtain amorphous Ni-Co-P nanoparticles. Through exhaustive examinations, a highly electrocatalytic active (NiCo)OOH is generated on the surface of the highly electronic conductive Ni-Co-P during the course of UOR. The bimetallic synergy endows the catalyst with lower onset potential, lower charge-transfer resistances, and improved Ni redox reversibility compared with the Co-free sample. Benefiting from these merits, the optimal Ni-Co-P electrode (NCP-2) exhibits promising UOR performance with high catalytic current density (359 mA cm^-2), mass activity (143 A g^-1), and turnover frequency (TOF; 482 h^-1) at 1.40 V. Moreover, the NCP-2||Pt/C urea electrolyzer demonstrates robust catalytic performance sustaining a high current density of 200 mA cm^-2 for 48 h, and substituting UOR for oxygen evolution reaction (OER) reduces ∼15 % energy consumption for hydrogen production. Furthermore, NCP-2 shows reliable UOR catalytic behaviors even with the addition of common interfering substances, showcasing the great potential of the electroless-deposited electrodes for practical UOR applications.