Sulfur-Vacancy Engineering Accelerates Rapid Surface Reconstruction in Ni-Co Bimetal Sulfide Nanosheet for Urea Oxidation Electrocatalysis.

Developing a highly efficient catalyst for electrocatalytic urea oxidation reaction (UOR) is not only beneficial for the degradation of urea pollutants in wastewater but also provides a benign route for hydrogen production. Herein, a sulfur-vacancy (S) engineering is proposed to accelerate the formation of metal (oxy)hydroxide on the surface of Ni-Co bimetal sulfide nanosheet arrays on nickel foam (S-CoNiS@NF) for boosting the urea oxidation electrocatalysis. As a result, the obtained S-CoNiS@NF demonstrates an outstanding electrocatalytic UOR performance, which requires a low potential of only 1.397 V versus the reversible hydrogen electrode to achieve the current density of 100 mA cm. The ex situ Raman spectra and density functional theory calculations reveal the key roles of the S site and CoS in promoting the electrocatalytic UOR performance. This work provides a new strategy for accelerating the transformation of electrocatalysts to active metallic (oxy)hydroxide for urea electrolysis via engineering the surface vacancies.