AuNPs/g-C3N4/BiOCl0.5Br0.5 Heterojunction Sensitizing Sensor for Photoelectrochemical Sensing of 2-Chloroethyl Phosphoric Acid

Abstract A new strategy based on the graphite phase carbon nitride/non-integral bismuth oxychloride/bismuth oxybromide (g-C3N4/BiOCl0.5Br0.5) heterojunction and the plasma resonance effect of gold nanoparticles (AuNPs) was developed to construct a novel AuNPs/g-C3N4/BiOCl0.5Br0.5/ITO sensitized photoelectrochemical sensor for rapid and sensitive detection of plant hormone 2-chloroethyl phosphate (ETH). The morphology structure of the as-prepared materials and the characteristics of electrode film were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), and the photoelectrochemical response to ETH of the sensor was studied by electrochemical impedance spectroscopy (EIS) and current-time curve (i-t), etc. Density functional theory (DFT) was used to calculate the charge density of atoms in the g-C3N4/BiOCl0.5Br0.5 heterojunction, the electronic transition mechanism was analyzed, and the sensor's sensitization mechanism was further proposed. Furthermore, the relationship between the change of the sensor's transient current and the concentration of ETH was studied. Under the optimal conditions, ETH concentration in the range of 20.00 nmol/L–63.00 μmol/L had a good linear relationship with photocurrent, and the AuNPs/g-C3N4/BiOCl0.5Br0.5/ITO sensor exhibited high stability and high reproducibility. This study provided a feasible solution for the rapid and efficient detection of ETH, as well as a new sensing platform for detection of other plant hormones.