Preparation Of Few-layered Graphdiyne Nanostructures And Their Application In Detection

Graphdiyne（GDY）is a new carbon allotrope composed of alkyne bond（sp hybrid carbon atom）and benzene ring（sp² hybrid carbon atom）.Linear sp hybrid carbon atom and planar sp² hybrid carbon atom give GDY uniform distribution of pores,largeπ-conjugated structure and easily modified surface.These characteristics can enhance the adsorption capacity of GDY to analytes and improve the sensitivity of sensors,thus showing the application potential in the field of analysis and detection.In addition,the conductivity and specific surface area of GDY are also key factors affecting the sensor performance.Currently,the thickness of GDY reported for detection is mostly tens of nanometers,which affects its electron transport efficiency,and only the surface of GDY can strongly interact with the analyte.Therefore,the preparation of GDY with thin layer and large specific surface area,so as to provide more adsorption sites and obtain higher electron transmission efficiency,is the key to improve the detection sensitivity of the sensor.In this paper,an ultrathin graphdiyne/graphene（GDY/G）nanostructure was prepared by using liquid-exfoliated graphene（G）as epitaxy template,and loaded with hemin and Cu on GDY/G,and studied their application in the field of analysis and detection.The specific research content are as follows:1.Two-dimensional（2D）ultrathin GDY/G nanostructures were prepared in a solution containing hexaethynylbenzene by using liquid-exfoliated G as an epitaxial template and growing GDY on its sides.GDY/G exhibits lower electrochemical impedance and higher electrochemical active surface area,which is conducive to material diffusion and electron transfer.When GDY/G is used as electrode material in electrochemical sensor,it shows wide linear range and low limit of detection for heavy metal ions(Cd²⁺,Pb²⁺)and toxic molecules（nitrobenzene,4-nitrophenol）due to d-πandπ-πinteraction.In addition,hemin was immobilized to GDY/G byπ-πinteraction,and hemin/GDY/G was successfully used for ascorbic acid and uric acid detection.The prepared electrodes showed excellent recoveries and relative standard deviations in real sample detections,including river water,lake water,and serum,and flexible wearable UA sensors are also promising for the detection of UA in human sweat.2.Based on the successful preparation of GDY/G nanostructures,Cu/GDY/G nanomaterials with laccase-like nanozyme activity and photothermal property were prepared by loading Cu nanoparticle on their surface,and laccase-like nanozyme activity and photothermal conversion ability were tested.Cu/GDY/G was used as electrode material for the detection of hydroquinone,catechol and resorcin.Due to the synergistic effect ofπ-πinteraction between GDY and phenols,high laccase-like nanozyme activity and the high electron transport efficiency provided by G,the detection of hydroquinone,catechol and resorcin showed a wide linear range and limit of detection.The prepared electrodes show good recovery and low relative standard deviation in real samples（tap water,river water）.The Cu/GDY/G laccase-like nanozyme showed the highest degradation efficiency using the photothermal degradation model of catechol.3.Based on the successful preparation of Cu/GDY/G nanostructures,the experimental model composed of H₂O₂ and 3,3’,5,5’-tetramethylbenzidine（TMB）confirms that Cu/GDY/G has excellent peroxidase property.The mechanism of Cu/GDY/G enzyme-catalyzed reaction was evaluated from the perspective of kinetics.Based on this,the colorimetric detection mechanism of Cu/GDY/G-H₂O₂-TMB system for dopamine was established.It has low limit of detection（0.31μM）and wide linear range（0.5-150μM）for dopamine detection,and it has low relative standard deviation（≤3.06%）and good recovery（96.61%-102.60%）in actual samples（serum and urine）detection.