Seven Kinds of Electrochemical Sensing Research Based on Three Types of Nanocomposites

Author:Duan Cheng Zuo

Supervisor:zheng jian bin

Database:Doctor

Degree Year:2019

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Pages:117

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The nanocomposite has been developed rapidly due to its many advantages,such as large specific surface area,small size and rich active site.These advantages have promoted the development of the electrochemical sensing.The three types of nanocomposites-“transition metal and sulfide nanocomposites”,“SnO2 based materials”,“MOFs nanocomposites”were prepared by hydrothermal method,immersion method and in-situ polymerization method,etc.In this thesis,seven non-enzymatic electrochemical sensors based on three types of nanocomposites were constructed;the relationship between the size,composition,structure and morphology of the nanocomposite and the response performance of the electrochemical sensor was explored;and the new methods for the electrochemical detection of small molecules such as hydrazine hydrate(N2H4),nitrite(NO2-)and dopamine(DA)were established.The research was enriched by the contents of the electrochemical sensing and expanded the application range of the nano-materials.The full text concludes three chapters and the author’s main contribution are presented in three aspects:1.ElectrochemicalsensingresearchbasedonTernaryMetalSulfide nanocompositesTernary Metal Sulfide(TMS)nanocomposites such as FeCo2S4 and NiCo2S4 were synthesized through solvothermal method.The non-enzymatic N2H4 electrochemical sensors were fabricated which were based on FeCo2S4 and NiCo2S4 nanocomposites;the relationship between the size,composition,structure and morphology characteristics of the two functional nanocomposites and the response performance of the electrochemical sensors were also investigated;and the new methods for the determination of N2H4 were also established.The two types of nano-materials were characterized by XRD、FTIR、SEM and TEM techniques,showing that FeCo2S4 and NiCo2S4 were both spherical shaped network structure;they were79-105 nm and 303-368 nm in diameter respectively.And the particles size of NiCo2S4 was more uniform than FeCo2S4.The electrochemical study results showed us that the over-potential of the N2H4 non-enzymatic electrochemical sensor FeCo2S4/GCE was 0.9 V,the linear range were 2.8×10-55 mol·L-11.3×10-44 mol·L-11 and 1.3×10-44 mol·L-19.3×10-44 mol·L-1,sensitivity were 18897.0μA(mmol·L-1)-11 cm-2(in low concentration range)and 2590.0μA(mmol·L-1)-11 cm-2(in high concentration range)and the detection limit was9.33μmol·L-1;the N2H4 non-enzymatic electrochemical sensor NiCo2S4/GCE has reduced the over-potential to 0.38 V,the linear range were 1.7×10-66 mol·L-17.8×10-33 mol·L-1,and the detection limit was 0.6μmol·L-1,the sensitivity was 179.1μA(mmol·L-1)-11 cm-2.Compared with the first sensor in our work,the over-potential of the second sensor has been reduced 0.52V,the detection limits of the latter sensor was reduced one order of magnitude,and the linear range was broadened to four order of magnitude.This study can provide a reference for the preparation of network spherical nanomaterials.2.Electrochemical sensing research based on SnO2 nanocompositesThe nanocomposites AuNPs/SnO2,PANI/SnO2 and AuNPs/PANI/SnO2 which were based on metal oxide semiconductor nanocomposites as substrate were designed and synthesized by impregnation,in-situ polymerization,chemical reduction and hydrothermal method.Furthermore,the non-enzymatic NO2-electrochemical sensor were fabricated which were based on AuNPs/SnO2,PANI/SnO2 and AuNPs/PANI/SnO2 these three nanocomposites;the relationship between the size,composition,structure and morphology characteristics of the three functional nanocomposites and the response performance of the electrochemical sensors was also investigated;and the new method for the determination of NO2-in aqueous solution was also established.The three types of nano-materials were characterized by XRD、FTIR、SEM and TEM techniques,showing that the cloud-like AuNPs/SnO2 nanocomposites was assembled of 50 nm sleet and then AuNPs was absorbed on it;porous coral-shaped PANI/SnO2 nano-materials was 31-46 in diameter and 111-200 nm in length;AuNPs/PANI/SnO2 nanocomposites still kept porous coral-shape and AuNPs absorbed on it was also 10-17 nm in diameter.The electrochemical study results showed us that the over-potential of NO2-on AuNPs/SnO2/GCE was 1.02 V,the detection limit of NO2-non-enzymatic electrochemical sensor based on AuNPs/SnO2 was 0.9μmol·L-1,the linear range was 2.8×10-66 mol L-15.8×10-33 mol·L-11 and the sensitivity was 103.7μA(mmol·L-1)-11 cm-2;the over-potential of NO2-on PANI/SnO2/GCE was 1.02 V,the detection limit of NO2-non-enzymatic electrochemical sensor based on PANI/SnO2 was 0.04μmol L-1,the linear range was 1.2×10-77 mol L-17.8×10-33 mol L-11 and the sensitivity was 121.2μA(mmol·L-1)-11 cm-2;The over-potential of NO2-on AuNPs/PANI/SnO2/GCE was 1.08 V,the NO2-non-enzymatic electrochemical sensor based on AuNPs/PANI/SnO2 has a detection limit of 0.08μmol L-11 and a linear range of 2.5×10-77 mol L-11 to 2.4×10-33 mol L-1.Compared to the first sensor,the over-potential of NO2-on the second one kept the same,while the third sensor only raised 0.06 V,the detection limits of the latter two sensors were reduced one order of magnitude,and the linear range of the last two sensors were broadened one order of magnitude.This research extended the application range of gas sensing materials.3.Electrochemical sensing research based on Metal Organic Frameworks nanocompositesMetal organic frameworks(MOFs),also known as porous coordination networks or porous coordination polymers,was assembled from transition metals as metal clusters/ions with terephthalic acid as organic ligands through coordination bonds,possessing ordered porous networks structure.It synthesized through solvothermal method.The DA and N2H4electrochemical sensor were fabricated which were based on Fe-MOFs(Fe2Ni MIL-88B)and Zr-MOFs(UiO-66)the two nanocomposites;the relationship between the size,composition,structure and morphology characteristics of the two functional nanocomposites and the response performance of the electrochemical sensors was also investigated;and the new method for the determination of DA and N2H4 was also established.The two types of nano-materials were characterized by XRD、FTIR、SEM and TEM techniques,showing that the Fe2Ni MIL-88B was 633-967 nm in length and 100-167 nm in width,and octahedron shaped UiO-66 was 244-333 nm in diameter.The electrochemical study results show us that the linear range of non-enzymatic DA electrochemical sensor based on Fe2Ni MIL-88B was1.2×10-66 mol·L-11.8×10-33 and the detection limit was 0.4μmol L-1,the sensitivity was124.7μA(mmol·L-1)-11 cm-2;the N2H4 non-enzymatic electrochemical sensor UiO-66/GCE has reduced the over-potential to 0.57 V,the reaction rate constant of electrode(kf)was 243.7?10-22 cm s-1,charge transfer coefficient(α)was 0.72,the linear range was 5.0×10-7mol·L-17.8×10-33 mol·L-11 and the detection limit was 0.2μmol·L-1.Compared with the same type sensor in references in table,the sensitivity of the DA non-enzymatic electrochemical sensor increased nearly 13 times than others;the N2H4 non-enzymatic electrochemical sensor UiO-66/GCE has reduced the over-potential to 0.57 V,the linear range was broadened one order of magnitude and the sensitivity increased nearly 3.5 times than others.