Bismuth modified boron doped diamond electrode for simultaneous determination of Zn, Cd and Pb ions by square wave anodic stripping voltammetry: Influence of boron concentration and surface morphology

The optimization of electrode properties is an inseparable part of the analytical process which can highly improve the quality of obtained results in electrochemical sensing methods. This paper investigates the role of doping level, morphology and structure of boron-doped diamond (BDD) electrodes in electrochemical sensing of heavy metals in the presence of bismuth. To study the influence of doping level and morphology, a large set of BDD films with varying boron-to-carbon and carbon-to-hydrogen ratios in the deposition gas mixture was grown using hot filament chemical vapor deposition method. The set was used for fabrication of electrodes (the active area 0.43 mm(2) was opened in 400 nm SiO2 by standard optical lithography) for simultaneous electrochemical determination of zinc, cadmium and lead. Square wave anodic stripping voltammetry was utilized for this purpose. The influence of BDD properties on limit of detection (LOD) and sensitivity (S) of the electrodes was also investigated. The highest sensitivity was observed for electrodes prepared with 10 000 ppm boron-to-carbon ratio and lower methane concentrations. The findings prove the importance of selecting an appropriate electrode prior to progressing to electrochemical measurements.