Improvement of the electrochemical properties of “as-grown” boron-doped polycrystalline diamond electrodes deposited on tungsten wires using ethanol

Abstract

The electrochemical properties of boron-doped diamond (BDD) polycrystalline films grown on tungsten wire substrates using ethanol as a precursor are described. The results obtained show that the use of ethanol improves the electrochemistry properties of “as-grown” BDD, as it minimizes the graphitic phase upon the surface of BDD, during the growth process. The BDD electrodes were characterized by Raman spectroscopy, scanning electronic microscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The boron-doping levels of the films were estimated to be ∼10²⁰ B/cm³. The electrochemical behavior was evaluated using the ${\text{Fe}}{\left( {{\text{CN}}} \right)}_{{\text{6}}} ^{{{{\text{3}} - } \mathord{\left/ {\vphantom {{{\text{3}} - } {{\text{4}} - }}} \right. \kern-\nulldelimiterspace} {{\text{4}} - }}}$ and ${\text{Ru}}{\left( {{\text{NH}}_{{\text{3}}} } \right)}_{{\text{6}}} ^{{{{\text{3 + }}} \mathord{\left/ {\vphantom {{{\text{3 + }}} {{\text{2 + }}}}} \right. \kern-\nulldelimiterspace} {{\text{2 + }}}}}$ redox couples and dopamine. Apparent heterogeneous electro-transfer rate constants $k^{0}_{{{\text{app}}}}$ were determined for these redox systems using the CV and EIS techniques. $k^{0}_{{{\text{app}}}}$ values in the range of 0.01–0.1 cm s⁻¹ were observed for the ${\text{Fe}}{\left( {{\text{CN}}} \right)}_{{\text{6}}} ^{{{{\text{3}} - } \mathord{\left/ {\vphantom {{{\text{3}} - } {{\text{4}} - }}} \right. \kern-\nulldelimiterspace} {{\text{4}} - }}}$ and ${\text{Ru}}{\left( {{\text{NH}}_{{\text{3}}} } \right)}_{{\text{6}}} ^{{{{\text{3 + }}} \mathord{\left/ {\vphantom {{{\text{3 + }}} {{\text{2 + }}}}} \right. \kern-\nulldelimiterspace} {{\text{2 + }}}}}$ redox couples, while in the special case of dopamine, a lower $k^{0}_{{{\text{app}}}}$ value of 10⁻⁵ cm s⁻¹ was found. The obtained results showed that the use of CH₃CH₂OH (ethanol) as a carbon source constitutes a promising alternative for manufacturing BDD electrodes for electroanalytical applications.