High-selective dopamine electrochemical sensor based on yolk-shell structural composites derived from Ni-MOF@COFTAPB-DVA

Covalent-organic frameworks (COF) and metal–organic frameworks (MOF) were promising precursors for porous carbon-based materials. Calcining individual COF or MOF is usually unfavorable when preparing electrochemical active materials that combine sensitivity, stability, and selectivity. In this work, calcining a core–shell structural Ni-MOF@COF TAPB-DVA prepared a yolk-shell structural composite (YS-Ni@NC), in which the N-doped carbon shell (NC) encapsulated the Ni nanoparticles yolk (NiNPs). A highly selective dopamine electrochemical sensor (YS-Ni@NC/GCE) was developed based on the YS-Ni@NC modified glassy carbon electrode (GCE). The NiNPs yolk in the derivates provided excellent electrocatalytic activity, and the N-doped carbon shell improved the composite conductivity, enhanced the structural stability, and reduced the nonspecific adsorption of uric acid and ascorbic acid through electrostatic repulsion force. The YS-Ni@NC/GCE electrode exhibited higher selectivity for dopamine than the control electrodes in the presence of uric acid and ascorbic acid due to the electrostatic interaction between YS-Ni@NC and the small molecules. At the optimal experimental conditions, the DA sensor showed a linear concentration range of 0.136∼70.0 μM with a detection limit of 0.041 μM. In addition, the electrochemical performance of the sensor was stable when stored at room temperature for 30 days. Preparation of the yolk-shell structural MOF@COF derivates provided a new approach for fabricating highly selective non-enzymatic dopamine electrochemical sensors.