CdS nanotubes thin film for electrochemiluminescence analysis of phenolic compounds

A CdS nanotubes (NT) thin film has been fabricated to determine phenolic compounds based on the electrochemiluminescence (ECL) quenching of the CdS NT. The CdS NT thin film coated on an indium tin oxide substrate exhibits strong ECL emission with potassium persulfate (K ₂S ₂O ₈) as a coreactant. The effects of pH, electrolyte concentration and cyclic voltammetric scan rate on the ECL were studied. The quenching efficiency is governed by the position of the hydroxyl moiety in the parent benzene ring which follows the trend: resorcinol (1,3-benzenediol) > catechol (1,2-benzenediol) > hydroquinone (1,4-benzenediol) ≈ phenol. Under the optimal experimental conditions of 0.010 M K ₂S ₂O ₈, pH 11.60 and 0.10 V s ^-1, the quenching of ECL by catechol (2.0-10.0 μM), hydroquinone (40.0-140 μM), phenol (10-60 μM) and resorcinol (2.0-12.0 μM) follows Stern-Volmer behaviour. The limits of detection are calculated as 0.058, 0.64, 1.7, and 0.069 μM (S/N = 3) for catechol, hydroquinone, phenol, and resorcinol respectively. The fabrication of the CdS NT film is reproducible and its shelf-life is longer than three months. The CdS NT film has been successfully applied to determine the phenol contents in various environmental water samples with satisfactory results and good recoveries. Our proposed ECL CdS NT film provides a simple and convenient method for the detection of phenolic compounds and shows potential use in the pharmaceutical industry and environmental monitoring.