不同氧化程度的掺硼金刚石膜电极的电化学性能及电荷转移速率研究

Electrochemical Performance and Charge Transfer Rate of Boron Doped Diamond with Different Oxidation Extent

通过阳极电化学氧化法,制备不同氧化程度的掺硼金刚石膜(BDD)电极,并对其进行表征。分别采用循环伏安法和Mott-Schottky曲线,研究不同氧化程度的BDD电极的电化学性质和电荷转移速率。扫描电子显微镜和拉曼光谱分析表明,氧化后的BDD电极形貌和晶型结构几乎未发生变化,但EDX能谱分析发现BDD表面氧含量明显增加。循环伏安法和Mott-Schottky曲线阳极电流法研究发现,电荷转移速率随氧化程度的增大而逐渐增大。接触角实验进一步证实,随着BDD电极氧化程度的增加,接触角减小,电极表面亲水性逐渐增大,因此以阳极电流方式表示的电荷转移速率增大。然而,Mott-Schottky曲线以氧化还原电位差方式表示的电荷转移速率随氧化程度的增大,先增大,后减小,这是由于在不同的氧化时间下,表面基团的种类及其各成分在总含氧量中所占比例不同,因此产生的电荷转移速率也不相同。

The boron doped diamond （BDD） with different oxidation extent was prepared through electrochemical anodic oxidation, followed by characterization with various methods. The electrochemical properties and charge transfer rates of boron doped diamond electrodes with different oxidation extent were investigated by cyclic voltammetry and Mott-Schottky plot. As results, BDD morphology and quality rarely changed after oxidation by scanning electron microscopy and Raman scattering spectroscopy techniques, while the O/C＋O ratio obviously increased through EDX analysis. With the help of cyclic voltammetry and Mott-Schottky plot expressed by anodic current, it showed that the charge transfer rate enhanced with the increase of BDD oxidation extent. Moreover, the surface wettability decreased with the increasing oxidation extent, thus the hydrophilic property enhanced, suggesting the charge transfer rate expressed by anodic current increased. However, results from Mott-Schottky plot expressed by redox potential difference showed completely different result, i.e., the charge transfer rate increased and then decreased. This may be due to the kinds and ratios of functional groups on the BDD surface at different oxidation time, which may cause different charge transfer rates.