Morphological and Electronic Regulation of Zn,S-Incorporated FeCo-LDH Nanosheets for Boosting the Bi-Electrocatalytic Oxygen Evolution and Urea Oxidation Reactions

Developing high-performance and low-cost electrocatalysts for the oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is essential for hydrogen production. Herein, we prepared Zn,S-incorporated Fe,Co layered double hydroxide (ZnCoFeS-LDH) nanosheets on nickel foam via a two-step hydrothermal reaction. The attractive two-dimensional (2D) nanosheet morphology with ultrathin thickness offers abundant active sites, promotes the adsorption and desorption of intermediates on the surface, and also facilitates mass transportation. The electronic structure of ZnCoFeS-LDH was modified, which thus improves their conductivity, offers high-valence iron ions (Fe3+), and therefore intrinsically enhances their electrocatalytic properties. In particular, the constructed crystalline/amorphous interfaces benefit electron transfer between different phases. As a proof of concept, we examined the electrocatalytic performances of ZnCoFeS-LDH nanostructures to both the OER and UOR. As a result, the ZnCoFeS-LDH nanosheets exhibit excellent catalytic OER activity, with low overpotentials of 202, 217, 238, and 261 mV to achieve current densities of 10, 20, 50, and 100 mA cm(-2), respectively, which are remarkably enhanced in comparison with that of commercial RuO2. Furthermore, they also demonstrate outstanding durability after long-term (48 h) and cycling (5000 cycles) measurements. Moreover, the ZnCoFeS-LDH nanosheets also possess superior UOR activity. The potentials were measured to be as low as 1.313, 1.334, 1.366, and 1.398 V to reach current densities of 10, 20, 50, and 100 mA cm(-2), respectively, with high long-term stability after 20 h.