Preparation Of Graphene Quantum Dots By Laser Induced PDMS

Graphene quantum dots(GQDs),as a new zero-dimensional carbon nanomaterialas,not only have the excellent properties of graphene,but also have excellent properties such as low cytotoxicity,superior fluorescence stability,and excellent biocompatibility due to quantum confinement effect and edge effect.It has been widely used in many fields such as biological imaging,fluorescence sensing,optical devices,etc.,and has received extensive attention from the academic community.The traditional preparation methods of GQDs can be divided into top-down and bottom-up methods,but their application and development are greatly limited due to the complex preparation methods,high cost and long preparation cycle.As a representative of rapid processing technology,laser-induced strategy has a series of advantages such as highly efficient,non-contact,easy operated and low pollution.As a pioneering method,laser-induced graphene(LIG)achieves rapid and green preparation of graphene while avoiding the disadvantages of complex and time-consuming traditional methods.This method does not require an overly harsh experimental environment,does not require any chemical reagents,is simple,fast,and has abundant precursors.Through simple laser beam scanning,Graphene patterns can be formed directly on polymers with micron-scale resolution.Therefore,the introduction of laser induced process into the preparation of GQDs has become a research direction of green preparation and large-scale development of GQDs.In order to further explore the green method of laser preparation of GQDs and achieve the low-cost and rapid preparation of GQDs,this paper mainly studied the method of laser induced preparation of GQDs on low-cost PDMS precursor.The main research contents are as follows:1.Using polydimethylsiloxane as carbon source,a method to prepare GQDs using 532nm laser induced polydimethylsiloxane(PDMS)was proposed.The method was divided into two steps.Firstly,PDMS was used as the precursor to prepare low-cost and high-quality graphene by controlling the laser parameters,and then GQDs was prepared by hydrothermal method using the prepared graphene as the precursor.The laser parameters of graphene prepared by laser-induced PDMS were explored.After Raman spectrum analysis,the laser power of 0.8 W,scanning repetition of 3 times and scanning rate of 1 mm/s were the best laser parameters,and the graphene prepared had smaller defects and lower layers.Then,the morphology,fluorescence and structure of the prepared GQDs were characterized,it can be concluded that the prepared GQDs emit bright blue fluorescence under the irradiation of 365nm UV lamp,the average particle size is about 6.67 nm,and the quantum yield is about 6.3%,with stable fluorescence properties.2.In order to further improve the yield and simplify the steps,taking polyimide(PI)/polydimethylsiloxane(PDMS)composite as carbon source,a method of preparing GQDs by532 nm laser-induced PI/PDMS composite is proposed,which can realize one-step preparation of GQDs.Firstly,Reax FF molecular dynamics was used to simulate and analyze the GQDs prepared by the laser-induced filler PI.The results showed that PI could form a graphene structure,which was mainly composed of six-membered carbon rings,and also contained five-membered and seven-membered carbon rings.A small amount of N atoms were doped in the graphene structure,and H atoms were modified at the edge of the structure.The O,H and N elements in PI are mainly released as CO,H₂gas and C_xH_yN_zgas.Through the characterization and analysis of GQDs prepared by laser induced PI/PDMS,the prepared GQDs can emit bright blue fluorescence under the irradiation of 365 nm UV lamp,the average particle size is 6.14 nm,and the yield is about 11.4%.The fluorescence are stable,and the special detection of Fe³⁺ions is realized.