Amplified electrochemical detection of sulfadiazine based on Cu-BTC-encapsulated FeNi dual-atom catalysts with improved catalytic efficiency

The amplification of detection signals is an important method for improving the sensitivity of electrochemical detection. This study presents an efficient strategy for preparing electrochemical catalytic materials using a simple self-assembly technique to encapsulate Fe single atoms (Fe–SAs) and Ni single atoms (Ni–SAs) in the Cu-benzene-1,3,5-tricarboxylic acid (Cu-BTC) metal–organic framework to form a Cu-BTC@FeNi–SAs catalytic system. Subsequently, Cu-BTC@FeNi–SAs was modified on the surface of a gold electrode, and sulfadiazine was used as a template to prepare a molecularly imprinted polymer (MIP) on the modified electrode. After eluting sulfadiazine, an MIP was obtained for specifically recognising sulfadiazine. When sulfadiazine was adsorbed by the MIP, a differential pulse voltammetry (DPV) signal occurred in response, thus detecting sulfadiazine. The adoption of Cu-BTC-fixed FeNi–SAs significantly facilitated mass transfer during the reaction, thus improving the DPV response signal. When used to detect sulfadiazine, the sensor had a linear range from 5 × 10−12 to 6000 × 10−12 mol L−1 and a detection limit of 1.14 × 10−12 mol L−1. It also successfully detected sulfadiazine residue in seawater and fish samples with recovery rates between 91.02% and 99.20%.