Synthesis Of Gold@carbon Nanocomposites And Their Application In Electrochemical Sensin

It has been widely accepted that the discharge and residue of diverse pollutants would not only cause enormous harm to Mother Nature but also produce a severe hazard to human beings with the continuous progress of production technology in human society.Hence,it is of enormous significance for the efficient quantitative analysis of these toxic substances.Excitingly,various electrochemical sensors have been promptly developed and put into the utilization on account of inexpensive raw materials,fast response/recovery time,and facile operation procedure.Currently,the main factor limiting the performance of the electrochemical sensor is the electrochemical performance of the sensing probes.Among them,nanostructured gold（Au）has a fascinating attraction in the sensing realm,especially in electrochemical sensors on account of its large specific surface area,magical light absorption,excellent electron transfer ability,and biomimetic enzyme catalytic performance.Furthermore,in accordance with different composite substrates,a variety of gold nanocomposites can be constructed on the basis of nanostructured elemental gold.Among them,these substrates include other metals（core-shell）,organic-carbon polymer materials,inorganic-carbon materials,semiconductor metal oxides materials,etc.Notably,not only could these novel gold nanocomposites possess the remarkable catalytic oxidation ability,but also exhibit excellent properties in other aspects such as stability and biocompatibility.Thus in this paper,some novel sensing probes based on gold@carbon（Au@C）nanocomposites,including the organic-carbon nanomaterials and the inorganic-carbon nanomaterials have been successfully fabricated to construct the electrochemical sensor with the aid of Nafion solution.Subsequently,these electrochemical sensors could achieve the efficient and accurate quantitative analysis of common pollutants in human daily life,and the details are shown as follows:1.Chemical preparation has been utilized in our work,that is,polydopamine nanospheres（PDA NPs）have been prepared in an alkaloid buffer solution and then HAu Cl₄has been reduced to Au nanoclusters（NCs）immobilized on the surface of the PDA NPs through electrostatic interaction.At the same time,with the help of molecular imprinting technology（MIT）,formaldehyde is used as the template molecule and acrylamide is chosen as the functional monomer,and then molecularly imprinted polymers（MIPs）were synthesized on the surface of as-prepared bi-nanospherical particles.Therefore,the Au@organic carbon nanocomposite sensing probes have been obtained.Under the action of Nafion solution（5wt.%）,the sensing probes were immobilized on the central surface of the highly oriented pyrolytic graphite（HOPG）electrode,thus an electrochemical sensor has been fabricated for the specific detection of formaldehyde in solution with a three-electrode system.Compared with other traditional analytical methods that can detect formaldehyde,this Au@organic carbon nanocomposite-based electrochemical sensor can not only sensitively detect formaldehyde in solution（limit of detection=0.1μM）but also can selectively detect formaldehyde in some similar isomers with excellent anti-interference.2.The biological template was utilized in our work.In detail,polydopamine nanospheres（PDA NPs）are isolated and purified from cuttlefish ink in vivo.Afterward,HAu Cl₄and Ag NO₃are reduced to gold@silver（Au@Ag）core-shell nanoclusters by a one-step approach which is anchored on the surface of the PDA NPs.Then by the topological transformation（TTF）technology,the above precursor has been transformed to Au@Ag core-shell NCs modified nitrogen-doped porous carbon（NPC）nanospheres,which can be utilized as novel ternary core-shell electrochemical nanoprobes.With the help of Nafion solution（5 wt.%）,the Au@inorganic carbon sensing probes have been immobilized on the surface of a highly oriented pyrolytic graphite（HOPG）electrode to construct an electrochemical sensor that can selectively detect resorcin in solution through a three-electrode system.Compared with some traditional analytical methods that can detect resorcin,this sensor based on Au@inorganic C nanocomposite has an extremely low limit of detection（0.06μM）and is capable of selective detection of resorcinol in a variety of isomers（hydroquinone,catechol,resorcin）.