介孔氧化镍微球的水热-热分解法制备及其在血红蛋白直接电化学检测中的应用

Hydrothermal and thermal decomposition synthesis of hierarchical mesoporous NiO microspheres and its application in direct electrochemistry of hemoglobin

以聚乙二醇-6000为模板剂,Ni(NO3)2.6H2O为镍源,通过微波水热法合成了Ni(OH)2前驱体微球,再采用热分解法最终获得介孔氧化镍微球,并对样品XRD、SEM、TEM和N2吸-脱附等结构表征。利用涂布法以离子液体为粘合剂,制备了固定血红蛋白(Hb)的复合工作电极,并对吸附于膜内的Hb电化学行为进行了研究。结果表明采用水热-热分解法可以获得直径为2.0μm颗粒堆积介孔氧化镍微球,该氧化镍微球具有高的比表面积(234m2/g)和窄的孔径分布(3.25nm)。循环伏安实验表明,在pH值=7.0的磷酸缓冲溶液中,Hb表现出一对峰型良好的准可逆氧化还原峰,为Hb Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰,对其直接电化学行为进行了研究,求出电位为-0.278V(vs Ag/AgCl),电子转移数为1.104,电荷传递系数为0.476,表观异相电子转移速率常数为0.775s-1。

Hierarchically nanostructured NiO microspheres self-assembled by nanoparticles with mesoporous structure were successfully prepared via a microwave hydrothermal and subsequently controlled thermal decom- position method, by using Ni（NO3）2 · 6H2O as raw materials and poly ethylene glycols （Mw=6000） as a soft template, respectively. The as-prepared sample was well characterized by X-ray diffraction （ XRD ）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and N2 absorption-desorption isotherm techniques. The experimental results shown that the as-obtained hierarchical mesoporous nickel oxide microspheres have a high surface area of 234m^2/g and narrow pore distribution at 3.25nm. Direct electrochemistry of hemoglobin （Hb） was investigated on a room temperature ionic liquid modified NiO paste composite electrode. Hb was immobilized on the composite electrode and a pair of well-defined, quasi-reversible cyclic voltammetric redox peaks was obtained, which was characteristics of Hb Fe（ Ⅲ）/Fe（ Ⅱ ） redoxs couples. The formal potential （E^0＇） , the electron transfer number （n）, and transfer coefficients （a） was calculated as -0. 278V （vs Ag/ AgCl）, 1. 104 and 0. 476, respectively, which indicated that one electron was transferred between heme group of Hb and the electrode. The average apparent heterogeneous electron transfer rate constant （ks） obtained for Hb was 0. 775s^-1.