基于多壳层Co3O4中空正十二面体的高效葡萄糖传感器

Hollow multi-shelled Co3O4 dodecahedra for nonenzymatic glucose biosensor

对比了多壳层Co3O4中空正十二面体与有序介孔Co3O4作为电催化剂,并应用在葡萄糖电化学催化氧化中的反应行为.多壳层中空结构促进了葡萄糖分子及相关产物的反应扩散,而壳层纳米粒子的取向排列不仅优先暴露了更多高活性(111)晶面也能促进反应电子的转移,从而有效提高了对葡萄糖电催化氧化的活性.多壳层中空正十二面体在低浓度范围对葡萄糖的灵敏度可达4075.2μA mmol/(L cm^2),优于有序大介孔Co3O4和有序小介孔Co3O4分别为3561.1和2074.3μA mmol/(L cm^2).电化学性能结果表明,多壳层Co3O4中空正十二面体是一种构筑葡萄糖传感器的优异电催化剂,为高效葡萄糖电催化剂的设计与合成提供了一定的借鉴.

Electrochemical oxidation of glucose has been attracting more and more attention because of its importance in the development of advanced glucose biosensing or biofuel cell for various medical applications,where electrocatalysts with high activities are viewed as one of the most critical factors to determine the performance in these electrochemical devices.There are usually three strategies to enhance the activity of an electrocatalyst system by increasing the number of active sites on the specific electrocatalyst,the intrinsic activity of each active sites and the ability to transfer charges.The utilization of various nanocatalysts with high specific surface areas is the most common way to increase the number of active sites,whereas the intrinsic activity of each active sites is mainly related to the component and crystal structure of catalysts as well as the type of exposed facets,which are partially responsible to the charge conductivity too.In principle,these three strategies are independent and not mutually exclusive,which could be ideally placed together for being comprehensively considered.However,it is still a great challenge to realizingly describe the relation of these three strategies and simultaneously realize the optimization of these three strategies in an electrocatalyst system owing to the limitation of mass and charge transport,which usually leads to a lower practical performance than the theoretical value from increasing active surfaces.Considerable efforts have been devoted to discovering and developing electrocatalysts with different compositions from noble metals,carbon,to transition metals and their hydroxides or oxides and different mesostructures from nanoparticles,nanowires,nanosheets to their three-dimensional superstructures.Among of them,hollow Co3O4 nanomaterials are well-known to be a kind of promising electrocatalyst due to their multiple valence states and unique mesostructures.Especially,hollow multi-shelled structure(Ho Ms)of Co3O4 nanomaterials possess some advantages over their counterparts with only one shell,such as more active surfaces,better stability,and usually exhibit higher performance.Herein,we present a nonenzymatic glucose biosensor based on hollow multi-shelled Co3O4 dodecahedra,which obtained from the thermal transformation of Co-based metal-organic framework(ZIF-67).Morphology,crystal structure and electrochemical property of hollow multi-shelled Co3O4 dodecahedra were characterized by using X-ray diffraction,transmission electron microscope,N2 physisorption,cyclic voltammetry,amperometry,and electrochemical impedance spectroscopy.Due to the topological arrangement of Co atoms in ZIF-67,the oriented assembly of Co3O4 nanoparticles in hollow dodecahedra leads to a porous shell with more exposure of(111)facets,which allows for the improved molecule-diffusion and charge-transfer properties as well as enhanced catalytical activities for the electrooxidation of glucose.As a result,multi-shelled hollow Co3O4 hollow dodecahedra gives a high sensitivity of 4075.2μA mmol/(L cm^2)toward glucose at a low concentration level of 0.01-0.338 mmol/L,which is superior over ordered mesoporous Co3O4 with large and small mesopores of 12 and 4.5 nm(3561.1 and 2074.3μA mmol/(L cm^2),respectively).This work demonstrated the potential of hollow multi-shelled Co3O4 dodecahedra as a novel electrocatalyst for advanced nonenzymatic glucose biosensor,which will bring more opportunities for designing and developing other electrocatalysts with higher activities.