Preparation And Application Of Electrochemical Sensor Based On Biomass Carbon Materials

The advent of nanoscience and nanotechnology has opened new horizons for researchers,and carbon nanomaterials are considered the cornerstone of numerous studies in this regard.So far,a variety of functional carbon nanomaterials have been developed by using biomass as a carbon precursor due to its renewability,low cost,and abundant sources.Biomass-derived porous carbon materials have been used in electrochemical sensor research due to their unique properties,such as unique structures,sustainability,and environmental friendliness.The porosity,specific surface area,and graphitic properties of biomass carbon materials have great influence on the performance of electrochemical sensors.In order to improve the electrocatalytic performance of the working electrode,the experimental conditions were optimized to improve its surface properties.In this paper,biomass physalis alkekengi husks and azaleas were selected to activate and carbonize biomass to prepare biomass carbon materials with large specific surface area,abundant defect sites and excellent electrical conductivity,which were constructed as new electrochemical sensors.Such sensors are used for the analysis of small molecule ascorbic acid and uric acid,as well as the detection of actual samples.It mainly includes the following contents:（1）Using physalis alkekengi husks as carbon precursor,physalis alkekengi husks-derived carbon materials（PCM）was prepared by high temperature carbonization,and physalis alkekengi husks-derived graded porous carbon materials（KPCM）was prepared by KOH activation.Characterized by scanning electron microscopy,X-ray diffraction and nitrogen adsorption and desorption isotherms,KPCM has a larger specific surface area(1345.45 m²g^-1)and more defect sites than PCM without KOH activation.Two carbon materials were used as electrode modifiers to modify the surface of glassy carbon electrode（GCE）to build carbon-based electrodes KPCM/GCE and PCM/GCE,and the electrochemical properities of KPCM/GCE,PCM/GCE and GCE were investigated that KPCM/GCE has higher electron transfer rate,higher electrochemical active area,smaller charge transfer resistance and wider potential window,and has higher catalytic performance for ascorbic acid.Therefore,ascorbic acid electrochemical sensing platform was constructed with KPCM/GCE.Linear sweep voltammetry showed that ascorbic acid had high sensitivity(334.03μA m M^-1cm^-2and 134.52μA m M^-1cm^-2)and low detection limit（0.92μM）（S/N=3）in the linear range of 0.005～1.6 m M.The method was applied to the the analysis and determination of ascorbic acid content in vitamin C chewable tablets.（2）In this study,for the first time,an electrochemical sensing platform based on biomass azaleas-derived carbon/thionine ratio was fabricated to simultaneously measure ascorbic acid and uric acid.Using biomass azaleas as carbon source,azaleas-derived carbon material（ACM）was obtained by high temperature calcination,and azaleas-derived graded porous carbon material（KACM）was obtained by KOH activation and carbonization.Compared with ACM,activated KACM has a large specific surface area,large pore volume and high defect degree.The two carbon materials were modified on glassy carbon electrode（GCE）,and the electrochemical evaluation shows that KACM/GCE has good electrochemical performance,strong catalytic performance for ascorbic acid and uric acid,and can well separate their oxidation peaks.Therefore,thionine（Thi）molecules were assembled on KACM/GCE,and Thi/KACM/GCE electrodes controlled the adsorption of ascorbic acid and uric acid.The optimum experimental conditions were the p H of the bottom solution 6 and the soaking time 15 minutes.Under the optimal conditions,the detection limits of KACM/GCE for ascorbic acid and uric acid are 24.8μM and 22.3μM（S/N=3）,respectively,when the linear range is 0.075～9 m M.The detection limits of Thi/KACM/GCE for ascorbic acid and uric acid are 6.4μM and 10μM（S/N=3）when the linear range is 0.05～9 m M.Therefore,Thi/KACM/GCE has wider linear range,lower detection limit and stronger catalytic performance for the detection of ascorbic acid and uric acid.The recovery rate of Thi/KACM/GCE for simultaneous detection of ascorbic acid and uric acid in human urine were in the range of 99.4%to 101.0%,and satisfactory results were obtained.