摘要
用循环伏安、交流伏安和交流阻抗法详细研究了Keggin型铬取代杂多离子PW11O39Cr(Ⅲ)(H2O)4-(PW11Cr)的电化学性质。循环伏安扫描表明,1.0 mmol.L-1PW11Cr的H3PO4-HAc-H3BO3缓冲溶液(pH2.16)在玻碳电极上有三对氧化-还原波,发生在1.30/0.631 V处的准可逆波属于Cr(Ⅲ)/Cr(Ⅴ)电对的双电子氧化-还原响应,而位于-0.553/-0.505 V和-0.782/-0.725 V处的两对可逆波则对应于W-O骨架的双电子还原-氧化响应。PW11Cr三对氧化-还原波的峰电位皆与溶液的pH有关,随着溶液pH的增大,峰电位负移,峰电流降低,阴极和阳极的峰电位差增大,电极过程的可逆性降低。由第一个W-O骨架还原波的峰电流与电位扫描速率平方根的关系得到PW11Cr在H3PO4-HAc-H3BO3溶液(pH 2.16)中的扩散系数为4.4×10-6cm2.s-1。交流阻抗谱表明,Cr(Ⅲ)/Cr(Ⅴ)电对的电极过程受异相电荷传递动力学控制,由相角与频率的关系得到其动力学参数ko为0.67 cm.s-1;而W-O骨架的两个电极过程则受扩散控制。PW11Cr的电极过程存在吸附步骤。
Electrochemical properties of the PW11Cr（Ⅲ）O4-39（PW11Cr） in H3PO4-HAc-H3BO3（pH 2.16） buffer were investigated in detail by cyclic voltammetry,AC voltammograms and alternating current impedance analyses.The result of cyclic voltammogram showed that three pairs of redox waves were observed on the glassy carbon（GC） electrode in H3PO4-HAc-H3BO3（pH 2.16） buffer solution containing 1.0 mmol·L-1 PW11Cr.The pair of quasi-reversible wave at 1.30/0.631 V belonged to Cr（Ⅴ）/Cr（Ⅲ） two-electron redox,while the two pairs of reversible waved at-0.553/-0.505 V and-0.782/-0.725 V belonged to W-O skeleton two-electron redox.When the pH value increased,the peak potential of the three pairs of two-electron waves shifted negatively and the peak current decreased,which showed that H＋ was involved in the electrode process.In addition,the difference of peak potential between anode and cathode for each pair of waves increased,which showed reversibility of electrode process decreased.The diffusion coefficient DO of PW11Cr calculated from linear relationship of peak current of the first skeleton reduction wave versus square root of potential scan rate was 4.4×10-6cm2·s-1 in H3PO4-HAc-H3BO3（pH 2.16） buffer.AC impedance of Cr（Ⅲ） was a semicircle without Wahlberg line occurred at high frequency,which showed the anode oxidation process was controlled by heterogeneous charge transfer dynamics.The dynamic parameter ko of electrode process was calculated from the relationship between phase angle and frequency.AC impedance of PW11Cr keleton reduction revealed the electrode process was controlled by diffusion.
出处
《中山大学学报（自然科学版）》
CAS
CSCD
北大核心
2011年第3期68-73,共6页
Acta Scientiarum Naturalium Universitatis Sunyatseni
基金
国家自然科学基金资助项目(20963003)
海南省重点科技资助项目(090803)
海南省自然科学基金资助项目(509009)
吉林省科技发展计划资助项目(20090595)
国家大学生创新资助项目(091165820)
