Study On Construction,Functionalization And Performance Of High Performance 3D Graphene Materials

The construction of three-dimensional graphene is the main way to utilize the excellent properties of graphene at the macroscopic scale.Graphene aerogel is one of the most important three-dimensional graphene materials,and has been widely used in the fields of sensing,energy storage,catalysis,biomedicine and so on.However,the excellent properties of graphene are still far from being fully reflected in existing graphene aerogel materials.It is of great practical significance to carry out research on the preparation,functionalization and performance of high-performance three-dimensional graphene materials.Point at the problem that the electrical and mechanical properties of graphene aerogel are not ideal as "large and empty",a multi-gelation method is established to prepare high-density graphene aerogel.The design of "puncture" and "mold" breaks through the limitation of increasing the density of graphene aerogel,caused by low water solubility of graphite oxide.The steady growth of graphene aerogel density leads to rapid improvement of electrical and mechanical properties;high-density graphene aerogel is functionalized by nitrogen doping,nitrogen-sulfur co-doping,introduction of sulphur,nano-gold stars and gold-palladium nano-alloys.As a result,the hydrophilicity and electrocatalytic activity are improved for ultra-sensitive electrochemical detection of DNA and dopamine.The detection limits were 3.9×10-22 g mL-1 and 3.6×10-10 mol L-1,respectively.To solve the problem of partial loss of electrical and mechanical properties by "tearing"before the use of graphene aerogel,a w/o/w multiple emulsion template method was used to prepare graphene aerogel microspheres.The electrical conductivity and BET specific surface area of the as-prepared graphene aerogel microspheres with micrometer length are 3250 S m-1 and 1252.7 m2 g-1,respectively.With ultra-high electrocatalytic activity,graphene aerogel microspheres were applied for electrochemical detection of acetaminophen,the detection limit was 5.7×10-9 mol L-1.Against the lack of specific functions of graphene aerogel,functionalized nanographene surfactants were designed and synthesized.The micro/nano-graphene hybrid aerogel microspheres were prepared by Pickering emulsion soft template method;The special PN interface of the semiconductor(nano-graphene)/conductor(micrographene)leads to higher electrocatalytic activity;The development of octadecylamine functionalized and dodecylamine with gold-palladium nanoalloys co-functionalized micro/nano-graphene hybrid aerogel microspheres,for electrochemical detection of acetaminophen and peanut allergen Ara h 1,with detection limits of 3.8×10-10 mol L-1 和 4.7×10-23 mol L-1,respectively.Aiming at the problem that the large-sized graphene sheets are easily overlapped and the active sites are greatly reduced,the graphene aerogel nanospheres are prepared by the Pickering emulsion template method with nanographene.The "Pickering Emulsion Soft Template" and"Slow Reduction with Hydrazine at Low Temperature" designs are used to construct a finer graphene network structure;the prepared folic acid/octadecylamine functionalized graphene aerogel nanosphere can specifically identify the HepG2,and produce a highly sensitive electrochemical response;While,the prepared octadecylamine functionalized graphene aerogel nanospheres have a highly sensitive electrochemical response to hydroquinone,with a detection limit of 4.9×10-12 mol L-1.For the problem that simple physical mixing cannot achieve deep fusion of graphene with functional materials.Histidine and octadecylamine co-functionalized nanographene is coordinated with rare-earth element,followed by fluoride ion exchange and high temperature hydrothermal reaction to obtain graphene/rare-earth hydrogel nano-microspheres.The microspheres are highly hydrophilic and the upconversion luminescence efficiency is 102.7 times that of the single rare earth nanoparticles.The microspheres have a large drug loading amount,and the targeted cancer therapy in mice is realized by the light-controlled release of the drug by nano gold,which demonstrate the great potential in biomedical application.