Thickness effects of Ni on the modified boron doped diamond by thermal catalytic etching for non-enzymatic glucose sensing

Sputtered nickel (Ni) layers modified boron-doped diamond (BDD) electrodes for non-enzymatic glucose sensor were fabricated by the thermal catalytic etching process in the hydrogen ambient. The effect of Ni thickness on the thermal catalytic etching and the electrochemical behavior of Ni/BDD electrodes for glucose oxidation were investigated. Scanning electron microscopy(SEM)and Raman spectroscopy were utilized to characterize the electrode morphology and composition, respectively. Marked by different thickness and morphology of Ni layer, three kinds of surfaces were obtained after thermal catalytic etching. The first is a roughened surface with most Ni nano-particles sinking into the BDD film, the second is with Ni micro-particles presented on the BDD film, the third is with residual lamellar Ni. Electrochemical results indicated that the electrochemical behaviors of those Ni/BDD electrodes were related to the surface structure. The second Ni/BDD electrode has the limit of detection (LOD) of 1.23 mu M with a sensitivity of 839.3 mu M-1 cm(2), which was ascribed to the numerous agglomerated Ni nano- and micro-particles presented on the roughed surface.