Preparation Of Hydrothermal Carbon-based Composite And Its Applications In Molecular Detection

Carbon is the most abundant and important element in nature. Carbon–based materials have a series of excellent performance. It has alwaysbeing a research hotspot to research and develop novel synthetic methodsfor preparation of these materials, expand their application field, andachieve the goal of good performance, high output and low consumption.Hydrothermal carbonization meets the development needs. It has lots ofcharacteristics superior to other preparation methods, which makes itoutstanding in preparing high-performance carbon materials. At presentthere are few reports about the applications of hydrothermal carbonmaterials in the field of molecular detection.Therefore this article willmainly prepare carbon-based precious metal composites by hydrothermalcarbonization and in situ reduction, and study their applications inelectrochemical analysis of dopamine and surface enhanced Ramanscattering (SERS) of rhodamine6G and malachite green. The mainresearch contents and results as follows:1. Homogeneous carbon spheres and Ag@HTC core-shell sphereswith smooth surface were synthesized by hydrothermal carbonization withglucose, glucose and AgNO3aqueous solution as raw materialsrespectively. The results of XRD, XPS, FT-IR, Raman, etc. showed thatthe two kinds of carbon materials are amorphous, and both of the surfacescontained rich oxygen-containing groups, such as carboxyl, hydroxyl etc.,which was beneficial to the surface modification.2. Because of reduction ability of oxygen-containing groups, Ptnanoparticles were in situ deposited on the surface of HTC sphere. Glassy carbon electrode was modified with the compound and was used for theworking electrode. The electrochemical analysis properties of dopaminewere studied using cyclic voltammetry. The results showed that threefactors, including the adsorption of dopamine and oxygen-containinggroups on the surface of HTC/Pt, the catalysis of dopamine by Ptnanoparticles and the huge contact area between the base solution and theelectrode, led to dopamine stronger electrochemical response signal on themodified electrode. In addition, the paper was also focused on the effect ofdifferent dispersions on electrochemical sensitivity and selectivity of thedopamine, which indicated that0.5wt%hexadecyl trimethyl ammoniumbromide has better comprehensive performance compared with0.5wt%Nafion and0.5wt%sodium dodecyl sulfate. The detection limit ofdopamine was as low as0.1μmol/L, and the anti-interference performancewas also quite good.3. Ag nanoparticles were in situ deposited on the surface of Ag@HTCcore-shell sphere, and their enrichment and aggregation degrees wereincrease gradually as the increase of AgNO3concentration in theself-reduction process. SERS results showed that the increase of quantity,density and size of Ag nanoparticles was beneficial to enhancing theRaman signal of the molecule. With Ag@HTC/Ag as the substrate, thedetection limit of rhodamine6G and malachite green was as low as10-11mol/L and10-10mol/L respectively. Highly sensitive detection of lowconcentration molecules could be realized.