Sulfur-vacancy-enriched MoS2-CNTs with highly dispersed Au particles for sensitive dopamine detection

Introducing targeted surface defects sites to regulate the electronic structure is a key method to enhance the electrocatalytic activity of materials. This study reports an electrochemical dopamine sensor using sulfur vacancy (Sv) rich MoS2-CNTs with coaxial hierarchical structure and highly dispersed active gold particles (Au-Sv-MoS2-CNTs). MoS2 with sulfur vacancies expands the layered structure beyond the MWCNT's cylinder rather than being restricted to its surface and has active Au deposition sites along the edges. With optimal conditions, the proposed coaxial, hierarchical-structured Au-Sv-MoS2-CNTs show remarkable detection performance for the rapid detection of DA at concentrations as low as 2 nM in phosphate buffered saline (PBS). In addition, the sensor selectivity and anti-interference qualities are evaluated using chronoamperometry. Furthermore, it successfully detected the analyte from injection of dopamine hydrochloride and bovine serum samples with recovery rates ranging from 99.3% to 102.6% and relative standard deviations (RSD) less than 5%. Density functional theory (DFT) simulations demonstrate that the modifications of Sv and Au NPs could tune the electronic structure of the sensor and facilitate the adsorption and electrocatalytic reaction of DA on Au-Sv-MoS2-CNTs. This study reveals that vacancy engineering and morphology control are emerging strategies for the fabrication of biosensors.