Electronic Structure Engineering in NiFe Layered double hydroxide via A first row transition metals doping as an Efficient Electrochemical oxidation performance of Sulfamethazine in food samples

Abstract

Layered double hydroxides (LDHs) are among the most promising electrocatalysts due to their excellent electrochemical performance for their electrochemical oxidation behaviour. On the other hand, NiFe-LDH suffers from several drawbacks, including poor electrical conductivity and a tendency to stack and aggregate. Therefore, to overcome these limitations, we engineered a series of first row transition metals doped in LDHs, NiFeM-LDH (M= Ti, V, Cr, Mn, Co, Cu and Zn) for the comparative electrochemical detection of Sulfamethazine (SMZ). From these electrodes, NiFeCu-LDH/GCE demonstrates the outstanding electrochemical oxidation of SMZ detection. This remarkable improvement arises from the partially filled eg orbital of Cu²⁺ (t2g6eg3), which induces a Jahn-Teller distortion and promotes strong electronic coupling between Cu and Ni/Fe layered hydroxide. Such structural distortion enhances electron delocalization and accelerates the Ni2+ to Ni3+ conversion, thereby increasing the electroactive sites. Moreover, the synergetic effect between the formation of Ni-O-Cu and Fe-O-Cu linkages further improves electrical conductivity and facilitates faster charge transfer. Therefore, the NiFeCu-LDH/GCE exhibits a very low detection limit of 11.23 nM and a high sensitivity of 0.0869 µA µM-1 cm-2, with over one month of storage stability. The real-time applicability in food and environmental samples (chicken, beef, milk, cheese, honey, and river water) reveals an outstanding recovery range. Therefore, from the obtained results, NiFeCu-LDH delivers outstanding electrocatalytic performance towards the detection of SMZ in food and environmental applications.