Reversible Phase Transfer Mediated Single Micellar Inverse Emulsion Synthesis Of Sulfide Quantum Dots

Metal sulfide nanocrystals are a class of semiconductors with excellent performance,which have broad application prospects in the field of green renewable energy due to their rich electronic,optical,and chemical properties.At present,the synthesis of small-sized nanoparticles still has shortcomings such as uneven distribution,difficult separation,poor stability,and high-temperature synthesis,which severely limit the performance of nanomaterials.In this paper,the reversible phase transfer method was used to endow metal ions with water-oil dual compatibility,and the synthesis mechanism of single micelle inverse emulsion was systematically discussed.Small-sized monodisperse metal sulfide nanocrystals were synthesized,and photocatalytic performance experiments were carried out.The specific research content is as follows:(1)Research on the mechanism of reversible phase transfer of metal ions to prepare dualsoluble organometallic precursors.The aqueous solution of metal ions is mixed with the ethanol solution of organic amines to form coordination complexes of metal ions and organic amines,and the metal ions are first transferred to the organic phase of isooctane,and then reverse-phase transferred.The process control factors of bidirectional transfer and diffusion of metal ions between water and oil phases were systematically studied,including ion concentration,type and dosage of organic amines,etc.,and the reversible phase transfer mechanism of metal ions was preliminarily investigated.The method can be widely used in the preparation of various water-oil dual-soluble metal ion precursors.(2)Research on the synthesis mechanism of monomicellar inverse emulsions and preparation of small-sized monodisperse metal sulfide quantum dots.Doubly soluble organometallic precursors are diffused from the organic phase into water droplets in an inverse emulsion,and react with sulfide ions in the water droplets to form metal sulfide quantum dots,which are then controlled for growth in a single micelle.It is demonstrated that organic amine ligands enhance the rigidity of micelles during the synthesis of single-micellar inverse emulsions,and the micelle coalescence is inhibited,and the process control factors of the synthesis mechanism of single-micellar inverse emulsions are investigated,including water and surface The active agent molar ratio,surfactant concentration and oil phase environment have basically proved the synthesis mechanism of single micelle inverse emulsion.The method can be applied to metal sulfide quantum dots with small size and good monodisperse stability.(3)Photocatalytic performance testing of silver sulfide.Silver sulfide quantum dots were prepared by reversible phase transfer mechanism and single micelle inverse emulsion synthesis mechanism.The photocatalytic degradation of methylene blue(MB)showed that the synthesized silver sulfide quantum dots had good photocatalytic performance.The degradation rate was as high as 50% within 40 min,and the entire degradation was basically completed within 140 min,which was a certain improvement over the reported single catalyst catalytic effect.It shows that the prepared metal sulfide nanoparticles have great practical value and potential value in the field of photocatalysis.In summary,in this paper,through the in-depth exploration of the reversible phase transfer mechanism and the synthesis mechanism of single micellar emulsion,small-sized monodisperse sulfide nanocrystals were prepared,and the silver sulfide degradation experiment of methylene blue proved that the prepared silver sulfide has excellent performance.Finally,this paper also provides a new direction and approach for the preparation of small-sized monodisperse sulfide quantum dots.