High-current-density PB@S-NiCo nanorod array catalyst for urea-assisted water splitting

To alleviate severe environmental and energy pressures, urea oxidation reaction (UOR) was frequently studied as an alternative electrochemical hydrogen production anode reaction for its low theoretical voltage. Herein, a series of self-supported UOR catalysts were synthesized on the combination of PB nanoparticles and sulfur doped NiCoCO3(OH)2 nanorod arrays (PB@S-NiCo NRA) on copper foam. By changing the modifying time of S-NiCo NRA precursor in K3[Fe(CN)6] solution, PB@S-NiCo-X (X=10, 60, 120 for reaction time) were obtained. The highly hydrophilic heterostructure array can adjust the interface electronic structure and accelerate the mass transfer process, thereby optimizing the thermal/kinetic dynamics of urea electrolysis hydrogen production. Over the typical PB@S-NiCo-60 catalyst, only 1.48V (UOR) and 1.83V (overall urea electrolysis) were required to drive a large current density of 500mAcm−2, showing excellent electrocatalytic activities of the composite catalysts. Furthermore, PB component in the composite catalyst enhanced the reaction kinetics to achieve good stability at high current densities. This study provides new ideas for durable urea electrolysis-assisted H2 production.