Silver-cuprous oxide nanocomposites and nanohybrids-based electrochemical nanoplatform for ultrasensitive chloramphenicol detection: Influence of external and internal nano-heterojunctions

Abstract

A new facile, green, and time-saving one-/two-step electrosynthesis approach is utilized for the preparation of Ag, Cu₂O nanomaterials (NMs), Ag-Cu₂O nanocomposites (c-Ag-Cu₂O), and Ag-Cu₂O nanohybrids (h-Ag-Cu₂O), which are applied as electrode modifiers for developing high-performance electrochemical nanosensors towards chloramphenicol (CAP) detection. We have attempted to evaluate the electrochemical activity of c-Ag-Cu₂O and h-Ag-Cu₂O with the intention of investigating the influence of external and internal metal-semiconductor nano-heterojunction on the kinetic pathway for interfacial electron transfer, electrocatalytic activity, and adsorption/diffusion capacity. Compared to c-Ag-Cu₂O, a more intimate contact and strong interfacial interactions between two single components at the nanoscale in h-Ag-Cu₂O can expand the heterojunction contact area at the inner interface and provide a more tightly combined interface. The excellent intrinsic electrical conductivity and high electron mobility of Ag NMs and Cu₂O NMs's superior electrocatalytic activity, coupled with novel properties that are only existent in Ag-Cu₂O nanohybrids such as tight contact interfaces and internal electron transfer pathways across abundant heterojunction interfaces, contributed to the significantly improved analytical sensing performance towards CAP. Under the optimized experimental conditions, the h-Ag-Cu₂O-modified electrode possessed a wide linear response in the CAP concentration range of 0.5 – 150 µM with high electrochemical sensitivity (1.64 µA µM^–1 cm^–2), and the detection limit was found to be 0.16 µM. Moreover, the developed electrochemical nanosensor demonstrated good repeatability, acceptable anti-interference ability, and excellent long-term storage stability. This work may provide a crucial intersection of interfacial engineering of internal metal-semiconductor nano-heterojunctions and high-performance electrochemical sensing platforms, opening up a new class of novel, hypersensitive, and ultraselective electrochemical sensors.