NiCo-based Two-dimensional Nanomaterials/Nanoporous Gold Needle Heterostructure For Electrochemical Glucose Biosensors

Diabetes has drawn great attentions in recent years because of the increasing number of people with diabetes.The real-time monitoring of glucose concentration is of great significance for the diagnosis and control of diabetes.Therefore,it is paramount to the development of low-cost and high-performance non-enzymatic glucose sensors for replacing the traditional enzymatic glucose sensors.The key to prepare high-performance non-enzymatic glucose sensor lies in the preparation of novel electrode materials and the research on the catalytic mechanism of various materials.In recent years,more and more two-dimensional materials are gradually applied in the field of glucose sensors due to its unique structure and physicochemical properties.Effectively synthesize two-dimensional materials and modulate the surface and interface of them is still a challenge for non-enzymatic glucose sensors with highly selectivity at neutral conditions.Based on the above research background,we prepared a disposable nanoporous gold needle/ultrathin NiCo₂O₄ nanosheets heterostructure material and a two-dimensional NiCo-MOFs nanosheets array material by electrochemical and hydrothermal method,respectively.The morphology and composition of the as-synthesized materials were characterized by X-ray diffraction?XRD?,scanning electron microscope?SEM?,EDX,Element mapping,transmission electron microscopy?TEM?,selected electron diffraction,high resolution electron microscopy,Raman spectroscopy,and X-ray photoelectron spectroscopy.Performances of the constructed non-enzymatic glucose sensors were also investigated.The research conclusions are as follows:1.Disposable nanoporous gold needle/ultrathin NiCo₂O₄ nanosheets heterostructure material was prepared by electrochemical methods for non-enzymatic electrochemical glucose sensor.Firstly,we prepared a new needle-type electrode with stainless steel needle as core of nanoporous gold,which can be applied to implantable and wearable devices.The introduction of needle-type stainless steel enhances its overall mechanical strength and reduces its cost,while nanoporous gold increases the conductivity and electrochemical active areas of transition metal oxides and prevents it from stacking.As a result,the material exhibits excellent performances for glucose oxidation at a low operating voltage of 0.45 V with a fast respond time of<1 s and a linear range of 0.01 to 21.24 mM with correlation coefficient of>0.999.This sensor has great potential for practical application and the work also provides a low-cost nanoporous gold as a new support material for other applications in the field of catalysis.2.Uniform 2D NiCo-MOF nanosheets array on the surface of nanoporous gold was prepared by bottom-up strategy without surfactant.A great sensing performance was obtained in the linear range of 1?M to 8 mM with a detection limit of 0.29?M and a response time of less than 1 s.The control experiments showed that only bulk MOFs were obtained from the conventional substrates of foam copper,nickel foam,and carbon cloth.The reason why vertical NiCo-MOFs nanosheets can be prepared by using nanoporous gold as the substrate is that the nanoporous gold can effectively prevent the stacking of MOFs nanosheets and its support effect.In addition,XPS indicated that the enhanced performance of NiCo-MOFs for glucose oxidation mainly due to the strong electron interaction among N,Ni,and Co.The research also provides a novel strategy for preparing new two-dimensional materials by using the bottom-up strategy.