Facile synthesis of silicon dioxide nanoparticles decorated multi-walled carbon nanotubes with graphitization and carboxylation for electrochemical detection of gallic acid

We proposed an efficient and scalable ultrasound-assisted approach for the synthesis of functionally integrated nanohybrid of silicon dioxide (SiO 2 ) nanoparticles and multi-walled carbon nanotubes with graphitization and carboxylation (GCMCN), which was employed to modify the glassy carbon electrode (GCE) for the fabrication of GCMCN@SiO 2 /GCE sensor. Graphitization of GCMCN contributed to the reduction of defect density and enhancement of electrical conductivity , and carboxylation of GCMCN improved the dispersion degree of carbon nanomaterial due to the hydrophilicity of carboxyl groups. SiO 2 nanoparticles possessed abundant binding active sites for target analytes due to the surface hydroxyl groups or silanol groups, which were beneficial for the enrichment of gallic acid (GA) molecules. For the functionally integrated GCMCN@SiO 2 nanocomposite, the interconnected conductive networks of GCMCN presented more efficient charge transport channels, which recompensed the non-conductive property of SiO 2 nanoparticles. Based on the functional collaboration of GCMCN and SiO 2 nanoparticles, the fabricated GCMCN@SiO 2 /GCE sensor presented good GA detection property (GA concentration: 0.01–15 μM, LOD value: 1.99 nM). The proposed sensor exhibited acceptable repeatability, reproducibility, and selectivity. Moreover, the good practicability performance could be effectuated at the GCMCN@SiO 2 /GCE sensor for the quantitative analysis of GA in black tea and green tea samples.