Voltammetric deposition of cobalt on carbon electrode for phosphate potentiometric sensor

Availability of phosphate sensors is very necessary in assessing the quality of agricultural soil. This study was aimed to develop a phosphate potentiometric sensor. Electrodeposition of cobalt (Co) on carbon electrodes was carried out by cyclic and linear sweep voltammetry using electrolyte solutions of CoCl2.6H2O and NH4Cl. Co-C electrodes resulting from electrodeposition were characterized using scanning electron microscopy (SEM), their performance was determined as a potentiometric sensor and the remaining electrodeposition solution was measured using a UV-Vis spectrophotometer. The measurement of the remaining deposition solution showed that the mass of Co deposited on the carbon electrode was 0.0174 gram and 0.0055 gram for the cyclic voltammetry method and the linear sweep voltammetry method, respectively. Co-C electrodes as potentiometric sensors were used to measure standard solutions of 0.01; 0.1; 1; 1; 100 ppm concentration of phosphate. The performance parameters of the Co-C potentiometric electrode designed by cyclic voltammetry, including correlation coefficient, detection limit, slope, and reproducibility were 0.9931; 2.3 ppm; 25.34; 1.71%. Meanwhile, for the electrodes designed using linear sweep voltammetry, the same performance parameter values were obtained respectively 0.9998; 1.3 ppm; 28.74; 1.463%. The performance of the phosphate sensor designed by linear sweep voltammetry shows better performance than cyclic voltammetry.