Electrocatalytic detection of para-hydroxybenzoic acid using metalloporphyrin conjugated microporous polymers

Electrochemical detection of para-hydroxybenzoic acid has been reported in this work using a metalloporphyrin-based conjugated microporous polymer-modified glassy carbon electrode. This study sought to design, synthesize, and investigate the influence of different central metals (Zn, Ni, Co) in porphyrin-based conjugated microporous polymers toward para-hydroxybenzoic acid detection. The 2,2ꞌ-bithiophene-5,5ꞌ-dicarbaldehyde, as an organic linker, was incorporated into the polymer to provide additional conductivity or electron transport within the conjugated system, overcoming the aggregation limitation of the metalloporphyrin monomers. Cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry techniques were employed to characterize the electrochemical behaviour and sensing properties of the modified electrodes. Under optimized experimental conditions, the fabricated cobalt(II)porphyrin conjugated microporous polymer sensor exhibited two linear segments in the ranges of 5.0–25 µM and 30–140 µM, achieving the detection limits of 0.133 µM and 0.244 µM, respectively. The modified electrode further demonstrated a high sensitivity value of 0.654 µM −1 cm −1 , and good recoveries > 94.3% (with relative standard deviation < 4.7%) in real water samples. The proposed electrochemical sensor, therefore, showcases the prospective application of the designed metalloporphyrin-conjugated microporous polymers and positions them as nanomaterials to advance and diversify the material in organic pollutant sensing platforms.