A Sensitive Urea Sensor Based NiO Nanoparticles Supported on the 3D Porous Carbonized Eggshell Membrane

Abstract

Urea (CO(NH2)2) is the main nitrogen-containing substance from the urine of human/animal, which is also an effective and critical indicator in evaluating various metabolic disorders. Urea can decompose naturally to toxic ammonia and nitrates permeating into groundwater, then cause environmental problems and even health issues. Therefore, the detection of urea concentration and decomposition of urea-rich sewage is vitally important in the human health and environmental industries. Urea oxidation reaction (UOR, CO(NH2) 2 + 6OH- → N2 + CO2 + 5H2O + 6e-) has been known as a viable method for renal/liver disease diagnostic detection. Here, we reported nickel oxide (NiO) nanoparticles dressed on the carbonized eggshell membrane (3D NiO/c-ESM) as a modified electrode toward urea detection. The unique network structure of ESM composed of biomacromolecular fibers provides a novel template for the functional groups, also with superior porosity and specific surface area, which can offer multiple transport pathways for both electrons and ions.Consequently, an integrated 3D network composed of NiO nanoparticles anchoring on the carbonized ESM using a mixed method of hydrothermal and pyrolysis. The NiO nanoparticles anchored 3D carbonized network of the catalyst provides more catalytic active sites and enables easy access of reactants to the catalyst surfaces. NiO/c-ESM modified electrode exhibits an outstanding performance for urea determination with a linear range from 0.05 to 2.5 mM, and limit detection of ∼20 µM (3σ). This work offered a green approach for introducing 3D nanostructure through employing biowaste ESMs as templates, providing a typical example for producing new value-added nanomaterials with urea detection.