Phosphorus-doped graphitic carbon nitride: A metal-free electrocatalyst for quercetin sensing in fruit samples

In this report, phosphorus-doped graphitic carbon nitride (PgCN), a metal-free catalyst, was prepared via a one-step thermal polymerization technique. Additionally, PgCN-x with a different weight ratio of phosphorous doping (x = 1, 2, and 3 wt %) was successfully synthesized and their structural and morphological properties were evaluated. The developed modified electrodes were engaged for the determination of quercetin (QCN) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. CV and DPV studies authenticate characteristic peaks ca. at +0.20 and +0.93 V (vs. GCE), respectively. Notably, the improved catalytic activity was perceived for PgCN-3 catalyst, which is 2-fold higher than pristine gCN, was possibly due to high phosphorous content. The quantitative analysis under optimized conditions revealed a comprehensive detection of QCN in the concentration range from 0.025 to 212.2 mu M with the lowest detection limit of 1 nM. Interestingly, impedance spectroscopy results disclose a piece of additional evident information to uncover the P-doping by comparing with pristine gCN in the presence of negatively charged redox couple. The currently developed electrochemical method was successfully employed to determine QCN in commercially available fruit juice samples with an acceptable recovery similar to 95%.

Automated summary

This report presents the preparation of phosphorus-doped graphitic carbon nitride (PgCN), a metal-free catalyst, using a one-step thermal polymerization technique. Different weight ratios of phosphorus doping were successfully synthesized and evaluated. The developed modified electrodes showed improved catalytic activity for quercetin (QCN) determination. A comprehensive detection of QCN in a concentration range from 0.025 to 212.2 μM with a low detection limit of 1 nM was achieved under optimized conditions. Impedance spectroscopy results provided additional information for P-doping. The developed electrochemical method was successfully applied to determine QCN in commercially available fruit juice samples with a recovery rate of approximately 95%.