Construction And Properties Of Electrochemical Sensors Based On Carbon Nanomaterials And Their Composites

In this dissertation,various carbon materials and their composites were fabricated by different methods to construct nanozymes,which were immobilized onto glassy carbon electrode by bovine serum albumin(BSA)and glutaraldehyde fixation(GLA)cross-linkers to construct electrochemical sensors for H2O2 detection at the negative working potentials.And electrochemical properties of as-prepared sensors were optimized and three kinds of substrate materials used for electrochemical sensors were developed.The main research contents and results were as follows:First of all,CeO2 nanoparticles were dirertly decorated on the surface of reduced graphene oxide(rGO)through the hydrothermal method and annealing process,the influence of cerium nitrate concentration,urea concentration,hydrothermal reaction time and reaction temperature on the morphology of CeO2/rGO nanocomposites were investigated.After that,CeO2/rGO nanocomposites were calcined in Ar atmosphere to form oxygen vacancy in CeO2 and form CeO2-x/rGO nanocomposites.Subsequently,CeO2-x/rGO nanocomposites were immobilized onto glassy carbon electrode by the cross-linking method to fabricate electrochemical sensor for H2O2 detection.Since oxygen vacancy can be generated after the calcination of CeO2 in argon atmosphere,the conversion of Ce3+/Ce4+ was realized,tanus CeO2-x showed reducibility towards the detection of hydrogen peroxide at low potentials.Due to the synergistic catalysis of rGO and CeO2-x,it was found that the electrochemical sensor based on CeO2-x/rGO nano composites exhibited high sensitivity(230.03μA·cm-2mM-1)and selectivity at negative potential.Secondly,ZIF-67 nanoparticles were prepared by aging method,nitrogen doped porous carbon nanomaterials were obtained with calcination in Ar atmosphere and etching process,and used as substrate to construct electrochemical sensors for H2O2 detection.Nitrogen doped porous carbon owned high specific surface area,excellent conductivity and good stability,therefore the nitrogen doped porous carbon showed excellent catalytic activity to H2O2 at low potential.The H2O2 electrochemical sensor based on nitrogen doped porous carbon nanomaterials exhibited high sensitivity and acceptable selectivity,the sensitivity was 386.47 μA·cm-2·mM-1 and a linear range from 50 μM to 4250 μM.Finally,on the basis of ZIF-67 nanoparticles,cerium was loaded onto the surface of ZIF-67 nanoparticles by ion exchange method.After calcination and etching process,nitrogen-doped porous C@CeO2-x nanocomposites were formed.The electrocatalytic performance of nitrogen-doped porous C@CeO2-x nanocomposites towards H2O2 detection improved greatly compared to pure nitrogen-doped carbon nanomaterials,the sensitivity of electrochemical sensor based on nitrogen doped porous C@CeO2-x nanocomposites towards H2O2 detection was up to 739.23 μA·cm-2.mM-1,the anti-interference ability had also been improved a lot and the linear range from 50 μM to 4750 μM was achieved.