Micro/nano-structured ultrathin g-C3N4/Ag nanoparticle hybrids as efficient electrochemical biosensors for l-tyrosine

Ultrathin (UT) g-C 3 N 4 with a thickness of ∼2 nm was prepared via a facile thermal exfoliation method using bulk g-C 3 N 4 as precursor. The UT-g-C 3 N 4 sample obtained exhibited a large specific surface area of 192.9 m 2 ·g −1 . The UT-g-C 3 N 4 /Ag hybrids were fabricated by a photo-assisted reduction technique. The morphology, microstructure and composition of the UT-g-C 3 N 4 /Ag hybrids were systematically characterized by transmission electron microscopy (TEM), aberration-corrected scanning transmission electron microscopy (STEM), STEM-energy dispersive X-ray (EDX) spectrometry, atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). Based on electrochemical impedance spectroscopy (EIS) results, the optimal UT-g-C 3 N 4 /Ag hybrids displayed a faster electron transfer rate in comparison of UT-g-C 3 N 4 and bulk g-C 3 N 4 . Moreover, in the presence of a phosphate buffer solution (pH = 6.0), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) results showed that the UT-g-C 3 N 4 /Ag hybrids coated on glassy carbon electrode (denoted as UT-g-C 3 N 4 /Ag/GCE) exhibited excellent electrochemical properties for l -tyrosine detection. It is observed that the electrochemical response of was linear in the concentration range of 1.00 × 10 −6 to 1.50 × 10 −4  mol L −1 with a limit of detection (S/N = 3) of 1.40 × 10 −7  mol L −1 , superior to the other reported sensors. The developed UT-g-C 3 N 4 /Ag/GCE sensor was employed for l -tyrosine detection in commercial l -tyrosine tablet samples, and the recovery of 97.2–99.3% was observed. This proposed g-C 3 N 4 -based electrochemical sensor provides a rapid and sensitive sensing method for l -tyrosine detection in real samples.