Research On The Preparation And Application Of Three-dimensional Graphene And Graphene-like Materials

Efficient utilization of solar energy for clean water is an attractive,renewable and environment friendly way to solve the water crisis,with important practical significance.However,conventional processes for solar steam generation generally rely on high-temperature heating of bulk liquids,which requires highly concentrated solar energy and suffers from high energy and optical losses.Therefore,it is important to explore and design solar energy absorbing materials to efficiently convert solar energy into heat energy.Recently,three-dimensional graphene materials have received extensive attention in the field of solar steam generation because of their low cost,efficient broadband absorption,porous structure and high solar-thermal conversion efficiency.In this paper,we use graphene oxide?GO?and melamine foam?MF?as raw materials to prepare nitrogen-doped graphene/carbon hybrid aerogel by a simple squeeze-absorption process,drying and carbonization at different temperatures for highly efficient solar steam generation.It has been found that NGCA carbonized at 600 ^oC?NGCA-600?exhibits excellent stability,efficient light absorption,good hydrophilicity for water supply and abundant micro-pores for vapor escape.The three-dimensional graphene composite achieves a solar-thermal conversion efficiency of 90%at the light density of 1 kW m^-2.This reusable solar-thermal convertible material has broad prospects of application in the fields of seawater desalination,water purification and sterilization.Hexagonal boron nitride?h-BN?is a graphene-like material with good thermal conductivity,chemical stability and unique optical properties.However,the preparation and performance studies of zero-dimensional boron nitride quantum dots?BNQDs?are still in their infancy.In this paper,boron nitride quantum dots?BNQDs?with blue fluorescence,functionalization and an average size of 3 nm were prepared by a simple hydrothermal method using boric acid and melamine as precursors.The as-prepared BNQDs were characterized by transmission electron microscopy?TEM?,high resolution TEM,atomic force microscopy,X-ray photoelectron spectroscopy,UV-vis spectroscopy,and fluorescence spectroscopy.We found that the prepared BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe³⁺with remarkable selectivity and sensitivity?the lowest detection limit was 0.3?M?.In addition,the fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome.Therefore,the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining,fluorescent probes,and biological labeling.