Rapid room-temperature fabrication of ultrathin Ni(OH)<inf>2</inf> nanoflakes with abundant edge sites for efficient urea oxidation

Key Words:Nickel compounds;Catalysis - Electrocatalysis - Electrocatalysts - Fuel cells - Metabolism - Nanosheets - Nanostructured materials - Oxidation - Precious metal compounds - Refractory metal compounds - Transition metals - Urea
Abstract:Ultrathin two-dimensional (2D) nanomaterials based on transition metal compounds can serve as alternative non-precious-metal electrocatalysts for urea oxidation reaction (UOR), which is vital to the development of direct urea fuel cells. Herein, we report a fast and room-temperature route to synthsize transition metal-based (Ni, Co, Mn) ultrathin 2D nanomaterials under ambient conditions. Theoretical and experimental studies demonstrate that the edges of Ni(OH)<inf>2</inf> are more active toward both the formation of NiOOH species and the adsorption of urea molecules than the basal planes, enabling accelerated catalytic kinetics for UOR. As expected, the β-Ni(OH)<inf>2</inf> nanoflakes manifest considerable electrocatalytic activity toward urea oxidation, reflecting 5.7 times higher current density (142.4 mA cm<sup>−2</sup>) compared to the β-Ni(OH)<inf>2</inf> nanosheets at a potential of 0.6 V vs Ag/AgCl. This work brings great promise for the design of advanced electrode materials in the field of electrocatalysis.<br/> © 2019 Elsevier B.V.
Volume:259
Translation or Not:no