Fabrication and electrochemical properties of boron-doped diamond film–gold nanoparticle array hybrid electrode

Citrate capped gold nanoparticle (AuNP) (∼15 nm) array with 20–50 nm spaces supported with amino-groups activated boron-doped diamond (BDD) film (AuNPs–BDD) has been fabricated through a self-assembly process. Surface states of BDD were characterized by XPS spectra and the topography of the AuNPs–BDD electrode was monitored with SEM images. The assembly kinetics of gold nanoparticle on the amino-groups activated BDD surface was also studied. Moreover, the basic electrochemical properties of as-grown BDD electrode, gold macroelectrode and AuNPs–BDD electrode were compared. Our result indicates that the AuNPs–BDD electrode shows much lower background current density comparing with gold macroelectrode. For the electrochemical response of Fe(CN)63-/4-, the signal-to-background ratio (S/B) is adjustable by controlling the AuNPs coverage on BDD surface. Furthermore, the electrochemical responses to electrolyte pH dependences for different types of redox couples, Fe(CN)63-/4- and RuNH362+/3+ on AuNPs–BDD electrode were also studied. The results suggest that the electron exchange rate between out-sphere type redox ions and AuNPs–BDD electrode is adjustable by changing the electrolyte pH.