Cu(II)-Grafted Carbon Nitride Quantum Dots with High Crystallinity for Photoelectrochemical Detection Application

The rapid growth of industry inevitably leads to a large variety of organic pollutants in the aquatic environment. The design of a photoelectrochemical (PEC) sensor is significant to achieve the goal of sensitive quantitative determination of organic pollutant residues. In this work, the graphitic carbon nitride (g-C3N4) quantum dots (CNQDs) with high crystallinity were synthesized through the step-by-step cutting of bulk g-C3N4, which were modified with Cu(II) and then utilized to the fabrication of a PEC sensor for monitoring the typical organic pollutant methyl viologen in water. In the detection process, by means of the redox of Cu(II)/Cu(I), Cu(II) can effectively accelerate the photogenerated carriers’ separation of CNQDs, and facilitate the reduction of methyl viologen, contributing to the notable photocurrent signal. More importantly, the stable PEC sensor presents a perfect linearity between the change in photoelectric signal and logarithm of methyl viologen concentrations ranging from 0.1 to 200 ng mL–1. Thus, the constructed Cu-CNQDs 2% can be widely utilized in the quantitative determination of methyl viologen in real monitoring of environmental pollutants.