Fabrication of Au/Ni/boron-doped diamond electrodes via hydrogen plasma etching graphite and amorphous boron for efficient non-enzymatic sensing of glucose

Amorphous boron powders were applied to grow boron-doped diamond (BDD) films with chemical vapor deposition method. The material is nontoxic and noncorrosive compared to conventional boron sources such as boroethane. The mechanism for using solid boron source as the dopant in low temperature and low pressure has been explained with a non-equilibrium thermodynamic coupling model and optical emission spectroscopic analysis. The BDD film was utilized in a non-enzymatic glucose sensor. A porous Au/Ni layer was then placed on the BDD surface for enhanced sensitivity. The electrode was characterized by scanning electron microscopy, Raman spectra, X-ray diffraction, cyclic voltammograms and amperometric responses. Typically operated at a voltage of 500 mV, it demonstrated fast response to glucose thanks to its large surface, rapid electron transfer, and synergetic effects between Au and Ni. Two specific linear ranges are found, one between 0.02 and 2 mM, and a second one between 2 and 9 mM. The detection limit and the best sensitivity are 2.6 μM and 157.5 μAmM⁻¹ cm⁻².