Structural Design And Performance Study Of Biomass-Based Electrode Materials For Non-Enzymatic Glucose Sensors

Diabetes can cause-damage-to-multiple-organs in the body-and-is a chronic disease that threatens human health.Currently,diabetes is still not completely curable,but can only be controlled or prevented.Therefore,it is of great importance to quickly and accurately detect the glucose level in blood.The traditional non-enzymatic glucose sensor electrode material is prepared by adding binder and conductive agent to the active ingredient and then coated on the glassy carbon electrode,which is easy to fall off the active ingredient after several tests,resulting in weak sensing performance and poor stability.Therefore,this paper aims to solve the problems of weak sensing performance and poor stability of traditional electrode materials by designing the fine structure of electrode materials and elucidating the correlation mechanism between microstructure and key performance in order to construct new,high-performance selfsupporting electrode materials.In this paper,based on two biomass substrates(hierarchical porous cellulose nanofibrils(CNF))aerogel and anisotropic wood-based carbon framework and one non-biomass substrate(three-dimensional porous nickel foam(NiF)skeleton),three novel self-supporting electrode materials were cleverly prepared by loading catalytically active substances such as Co3O4,cobalt-nickel hydroxide(CoNi-LDH)and CuS by methods such as plasma enhanced chemical vapor deposition(PECVD),hydrothermal method,calcination and electrodeposition,and analyzed the ability of these electrode materials to electrocatalyze the oxidation of glucose molecules.In addition,the superiority and gain mechanism of the unique microstructure and physicochemical properties of biomass substrates in improving the performance of catalytic oxidation of glucose are compared and illustrated in this paper.The main research content and results are as follows:(1)A conventional porous NiF skeleton was used as a substrate for the preliminary experimental exploration,and a layered micro-nano-mimetic structure(NiF@GNSCo3O4 NGs)was successfully constructed by coating a layer of graphene nanosheets(GNSs)on the NiF surface by PECVD,and then growing grass-like cobalt tetroxide(Co3O4 NGs)with the help of a combined hydrothermal and calcination technique The results showed that the NiF@GNS-Co3O4NGs electrode material exhibited good electrocatalytic performance,moderate linearity range(30.04 mM)and good intra-and inter-electrode reproducibility.DFT calculations indicated that the charge transfer from GNSs to Co3O4 improved the electron transport throughout the composite structure,as well as the formation of Co3O4 microsurfaces with strong adsorption energy for glucose surface,thus enhancing the sensing performance of the electrode material.(2)The linear range of electrode materials constructed with NiF as the substrate is relatively average,it was shown that the large pore size(micron level)of its substrate material NiF and the difficulty of adjustment was the key limiting factor.Therefore,for the performance bottlenecks,a new hierarchical porous CNF/PPy/CoNi-LDH selfsupporting electrode material is constructed using CNF aerogel with hierarchical porous structure as the substrate by a bottom-up method.The CNF aerogel substrate with microporous(<2 nm),mesoporous(2～50 nm)and macroporous(>50 nm)substrates can efficiently transport and store ions with its through-channel structure,enabling CNF/PPy/CoNi-LDH to exhibit a wider linear range(up to 35.5 mM)and a higher sensitivity(851.4 μA mM-1 cm-2).Meanwhile,CNF aerogels exhibit a surfacecontrolled ion transport mechanism with a faster ion migration effect relative to diffusion control,thus conferring a faster response time(2.6 s)and a low detection limit(0.56 μA)for CNF/PPy/CoNi-LDH.(3)In order to further improve the sensing characteristics of electrode materials,accelerating the ion migration rate is the key factor.Although the porous CNF aerogel has well-developed pore size and large specific surface area,its isotropic structure does not allow for the shortest ion migration path.Therefore,based on the previous work,a novel non-enzymatic glucose sensor was constructed by using wood with anisotropic channel structure with parallel growth direction as raw material and hollow flower-like CuS/carbonized delignified wood(HF-CuS/CDW)electrode material was prepared by alkaline cooking,calcination,and solvent heat method in a top-down approach.The results show that the anisotropic channel structure not only effectively shortens the diffusion path of these substances,but also the high-density anchoring of HF-CuS in the channel enhances the local reaction efficiency of glucose molecules.Therefore,the HF-CuS/CDW electrode material exhibits an ultra-wide linear range(up to 47.1 mM)and high sensitivity(2225 μA mM-1 cm-2)as well as a faster response time(1.4 s)for glucose.In addition,the trapping effect of this anisotropic wood-based carbon framework on interfering factors such as chloride ions significantly enhances the antiinterference and anti-toxicity of the HF-CuS/CDW electrode material.Meanwhile,the HF-CuS/CDW electrode material also exhibited excellent long-term stability(the current response value retained 95.3%of the initial value after 30 days),low detection limit(0.36 μM),and excellent intra and inter electrode reproducibility.Benefiting from the natural structure and rich pore structure of biomass materials,the prepared novel self-supporting electrode materials with large specific surface area and abundant active sites cleverly solve the problems of weak sensing performance and poor stability of traditional electrode materials,showing excellent stability and linear range.This research mainly prepares novel self-supporting electrode materials from biomass sources,which provides new ideas for the design and preparation of electrode materials for non-enzymatic glucose sensors,and is of great significance for reducing material costs,reducing environmental pollution and promoting electrochemical sensing technology.