Electropolymerized melamine on fluoride-free molten salt etching 2D niobium carbide MXene: A promising electrocatalyst for free radical antioxidant diphenylamine detection in food samples.

This work reports a fluoride-free synthesis of Nb2CTx nanosheets using a molten salt and Lewis acid etching approach, offering a safer and more efficient exfoliation route. To enhance the functional performance of Nb2CTx, we developed an electropolymerisation method to coat its surface with nitrogen-rich polymelamine (PM), utilising a potentiodynamic technique in a Cl--containing electrolyte. The Cl- ions facilitate the formation of NH3+ and -NH2 intermediates from melamine monomers, which subsequently interact with the oxygen-containing functional groups of Nb2CTx, leading to a stable PM@Nb2CTx composite. The fabricated PM@Nb2CTx electrode was applied to detect diphenylamine (DPA•+) sensitively, a chemical commonly used to prevent postharvest fruit damage during overseas storage. Amperometric studies demonstrated that the PM@Nb2CTx sensor offers an excellent detection limit of 161 pM with a wide linear range (1-8 nM). Results showcasing the potential of this material platform for real-time DPA detection and broader applications in food monitoring.