Performance improvement in chemical oxygen demand determination using carbon fiber felt/CeO2-β-PbO2 electrode deposited by cyclic voltammetry method

A three-dimensional (3D) structured electrode in which a compact CeO2-β-PbO2 particle layer on each carbon fiber in the felt (denoted as CF/CeO2-β-PbO2) was fabricated using cyclic voltammetry (CV) method in the presence of CeO2 nanoparticles in the electrolyte and supposed to be used as a sensor for in situ chemical oxygen demand (COD) detection. It was found that CeO2 was codeposited with PbO2 onto the anode, and the deposited crystals were tiny and compacted with each other. The electrochemical behaviors demonstrate that the fabricated CF/CeO2-β-PbO2 electrode possesses larger effective surface area, higher electrochemically catalytic activity, and better mechanical stability as compared with the anode without CeO2 deposited by CV method or constant potential (CP) method. The results of COD determination by the fabricated CF/CeO2-β-PbO2 electrode show a sensitivity of (3.0 ± 0.02) × 10−3 mA cm−2/mg L−1, a detection limit of 3.6 mg L−1 (S/N = 3) and a linear range of 30–8500 mg L−1 with correlation coefficient (R) of 0.9985 and RSD within 5 %.