Bimetallic NiCo Metal-Organic Frameworks with High Stability and Performance toward Electrocatalytic Oxidation of Urea in Seawater

Urea oxidation reaction (UOR) is an alternative anodic reaction for hydrogen generation via water splitting. The significance of UOR lies in both H۲ production and decontamination of urea-containing wastewater.[۱] Commercial electrocatalysts in this field are generally based on noble metals and show several limitations. Bimetal-organic frameworks (BMOFs) can be excellent candidates for the replacement of noble-metal-based catalysts, given their promising features such as tunable structure, high surface area, and abundant sites for electrocatalysis.[۲] In this study, a series of nickel-cobalt BMOFs (Nix-Coy-BMOFs: x and y refer to a molar fraction of Ni and Co) was synthesized and applied as electrocatalysts in UOR. In particular, a Ni۰.۱۵Co۰.۸۵-MOF material with a structure similar to its parent Co-MOF, revealed an exceptional electrocatalytic performance as attested by low values of overpotential (۱.۳۳ V vs. RHE at ۱۰ mA cm-۲), TOF (۰.۴۷ s-۱) and Tafel slope (۱۲۵ mV dec-۱). At ۴۰ mA cm-۲ current density, Ni۰.۱۵Co۰.۸۵-MOF also showed an excellent stability during ۷۲ h tests. This performance of NiCo-BMOF can be assigned to synergic effect between Co and Ni, abundant active sites, porosity, and tunable structure, which all result in increased reaction rate due to acceleration of charge and mass transfers. The present work thus introduces an efficient noble-metal-free UOR for energy generation from the urea-based wastewater.

کلیدواژه ها:

Metal–organic framework ، Bimetallics ، Urea oxidation reaction ، Seawater.