Boron doped nanocrystalline diamond microelectrodes for the detection of Zn2+ and dissolved O2

Boron-doped nanocrystalline diamond (B-NCD) films were grown by the hot filament chemical vapor deposition (HFCVD) technique on top of sharp electropolished tungsten substrates, in order to create amperometric microelectrodes (MEs) for detection of Zn2+(aq) and dissolved O2. The boron source was a B2O3 + ethanol mixture dragged by Argon gas through a bubbler. Different B2O3 concentrations were used to study the doping effect on the electrochemical behavior. The B-NCD MEs exhibited a working potential window of about 3.5 V in 5 mM NaCl, with low background current and good chemical inertness. The best electrochemical kinetics was achieved for the ME with highest boron doping content. The linear relationship between zinc concentration and zinc reduction current was found in a wide concentration interval from 10−5 M to 10−2 M of ZnCl2 in a 5 mM NaCl background. Measurements with a Fe–Zn galvanic couple immersed in 5 mM NaCl demonstrate potential applicability of the B-NCD ME for use in localized corrosion studies.

► We assemble boron doped nanocrystalline diamond microelectrodes with a wide working potential, particularly towards negative potentials.
► We perform the detection of Zn2+ in aqueous solution with boron doped diamond microelectrodes by cyclic voltammetry.
► We map the distribution of Zn2+ and dissolved oxygen in a model Fe–Zn galvanic couple by microamperometry.