A simple and efficient electrochemical sensor for determination of gallic acid based on multi-walled carbon nanotubes with carboxyl functionalization

We designed a simple and efficient electrochemical sensor for the determination of gallic acid (GA) by modifying the glassy carbon electrode (GCE) with the carboxyl-group functionalized multi-walled carbon nanotubes (MWCNTs-COOH). For this kind of carbon nanomaterial, MWCNTs-COOH possessed good electrical conductivity and enough specific surface area due to the one-dimensional hollow carbon skeleton with high charge transfer efficiency. Moreover, the carboxyl functionalization of MWCNTs-COOH could promote the homogeneous dispersion of multi-walled carbon nanotubes due to the enhanced surface wettability of carboxyl groups, which helped provide larger electrochemical active surface area and more efficient electron transport channels. Based on the above advantages, the fabricated MWCNTs-COOH/GCE sensor showed a low limit of detection of 0.0067 μM in the linear GA concentration range of 0.01-10 μM. In addition, the good reproducibility, repeatability, stability, and selectivity could be obtained at the fabricated sensor.