Facile Synthesis of Spinel-Type Copper Cobaltite Nanoplates for Enhanced Electrocatalytic Detection of Acetylcholine

Herein, we report the preparation of novel spinel-type CuCo2O4 nanoplates (CCO NPs) through a cost-effective, soft-template (citrate)-assisted method, followed by low-temperature calcination. In the synthesis process, the metal cations such as Cu2+ and Co2+ can react with citrate molecules via coordination interaction to form the CuCo-citrate at elevated temperature. During the calcination process at 500 degrees C, the citrate molecules were eliminated from the CuCo-citrate precursor via simple organic species, and thus, spinel-type CuCo2O4 nanoplates were formed successfully. Surface morphology, crystalline nature, and phase purity of as-synthesized CCO NPs were assessed by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS). As-synthesized CuCo2O4 nanoplates were used to construct a sensitive and reliable enzyme-free electrochemical sensor of acetylcholine (ACh) that shows a meaningful limit of detection (30 nM) with broad dynamic range (0.2-3500 mu M) covering the clinical range of ACh. Furthermore, the developed ACh sensor delivered long-term durability and good reproducibility. The point-of-care utility of the ACh sensor was demonstrated in spiked blood serum samples with acceptable recovery rates. The present work demonstrates a facile synthesis method with an extensive potential toward the preparation of binary transition metal oxides (BTMOs) for divergent electrocatalytic applications.