In-situ Nitrogen Doped Carbon Material As Electrochemical Sensing

In situ nitrogen-doped carbon-based materials with excellent characteristics,i.e.,simple,green,good conductivity,and excellent electrocatalytic properties,has been used for the modification of glassy carbon electrode?GCE?and then novel and sensitive electrochemical sensors have been prepared for organic analysis.?1?Scanning electron microscopy,transmission electron microscopy,UV-visible absorption spectroscopy,and Raman spectroscopy have been used to characterize the carbon material.?2?In situ nitrogen-doped graphene?C/N-Graphene?modified electrode is prepared and applied for simultaneous detection of hydroquinone isomers,which is an environmental pollutant.The electrochemical performance of C/N-Graphene is tested by cyclic voltammetry and electrochemical impedance spectroscopy,using[Fe?CN?₆]^3-/4-as a probe.The electrical signal of hydroquinone isomers?including hydroquinone HQ,catechol CC,and resorcinol RC?on the C/N-Graphene/GCE are significantly higher than that on the bare GCE and PDA-Graphene/GCE.The potential difference of HQ,CC,and RC is significant,which indicate that hydroquinone isomers can be detected by C/N-Graphene/GCE with high sensitivity and selectivity.Because of different electronegativity of nitrogen and carbon,the distribution of the electron cloud around carbon and the polar is affected,thereby electrochemical oxidation kinetics of hydroquinone isomers are changed,electrocatalytic activity is improved.The detection ranges of HQ,CC,and RC are 0.5-1000,0.5-460,and0.1-580?mol L^-1,respectively,with the detection limit?3S/N?of 0.251,0.144,and 0.072?mol L^-1.The concentrations of method hydroquinone isomer in pharmaceutical wastewater and the river have been detected with a recovery of 97.0-103.0%and its relative standard deviation?n=5?is less than 5%.?3?In situ reduced gold nanoparticles?Au NPs?with high conductivity and large specific surface area are combined with nitrogen-doped carbon spheres for the preparation of the electrode?C/N-Au/GCE?,because Au NPs can promote the redox potential,enlarge the difference of electrocatalytic oxidation kinetics for the difference of steric hindrance,and improve significantly the electrochemical signals.Compared with bare GCE,C-Au/GCE,C/N/GCE,and PDA-Au/GCE,the catalytic activity of nitrophenol and hydroquinone isomers on C/N-Au/GCE is the best.The electrode activity of C/N-Au/GCE can be maintained active at least two weeks.The method with detection range of 0.05-460?mol L^-11 and detection limit?3S/N?of 24-98nmol L^-1 has been used successfully for the actual water determination.?4?As a biomass-derived precursor,pork liver with rich nitrogen,iron,and carbon was calcined,metal organic ligand was carbonized,and then in situ iron nitrogen co-doped,uniform distributed porous carbon material?N/Fe-C?could be prepared with a facile and low-cost synthetic method.The characteristics of as-prepared N/Fe-C electrocatalysts were large surface area(665.1 m²g^-1),excellent electrical conductivity and electrocatalytic activity,and outstanding absorption ability for bioelectroactive molecules?e.g.,dopamine DA,uric acid UA,and acetaminophen PA?.The oxidation and reduction performances of these bioelectroactive molecules on the N/Fe-C electrode surface were different.Compared with GCE modified with nitrogen-doped carbon material?C/N/GCE?and GCE modified with removal of Fe elements nitrogen-doped porous carbon material?N-C/GCE?,the redox performance of N/Fe-C/GCE was improved significantly for Fe and N co-doping and could be utilized for simultaneous determination of DA,UA,and PA.The linear range and detection limit?3S/N?were in the range of 0.5-320?mol L^-1 and 10.6-79.0 nmol L^-1,respectively.This method was used for the analysis of actual blood with satisfactory results.The electrode of N/Fe-C/GCE could be still effective for at least two weeks.