Controlled Synthesis Of Ag₂S/Ag Janus Nanoparticles And Their Properties Investigation

Janus nanoparticles consist of two or more material phases, and usually possess multiple functional properties, resulting from the strong coupling interactions between different moieties, which make them promise potential applications across vast fields of medicine, catalysis, optoelectronic devices, etc. Silver sulfide semiconductor nanoparticles, due to its relatively large band gap and absorption coefficient, have NIR-FL signals, which have been widely investigated in the field of biomarkers, diagnostics, and in vivo imaging. Besides, the Ag nanoparticles, as a kind of important noble metal nanomaterials, have also excellent catalytic and SPR properties.In this thesis, we developed a novel one-pot surfactant reduction-based approach to controllable synthesis of Ag2S/Ag janus nanoparticles, via direct thermal decomposition of dithiocarbamate compounds. Furthermore, their optical properties and catalysis properties were also discussed. The contents of this thesis are as follows:1. A new strategy for one-pot direction preparation of Ag2S/Ag janus nanoparticles was proposed based on the thermal decomposition of single-source precursor silver diethyldithiocarbamate (Ag(DDTC)) at proper molar ratio of the surfactants of octadecylamine (ODA) and oleic acid (OA). The results showed that the surfactant ratio was ODA:OA?50:100, which resulted in the production of Ag2S/Ag janus nanoparticles. While the surfactant ratio was ODA:OA?100:50, which resulted in the production of Ag2S nanoparticles. The as-synthesized Ag2S/Ag janus nanoparticles had the average size of 10.12±0.87 nm with heterodimer structure, and exhibited two different lattices of monoclinic structure for Ag2S and face centered cubic structure for Ag. It was inferred that the surfactant of ODA as weak reluctant played a great role in the controlled synthesis of Ag2S/Ag janus nanoparticles. This one-step controlled reduction synthesis methodology for synthesis of Ag2S/Ag janus nanoparticles provide a facial approach for synthesis of janus nanomaterials.2. An alternative one-pot preparation of Ag2S/Ag janus nanoparticles was proposed based on the thermal decomposition of silver octadithiocarbamate from the mixture of CS2, ODA and AgNO3, and chosing ODA, myristylamine and octylamine as the reductant surfactants, respectively. Further investigation demonstrated that the Ag2S/Ag janus nanoparticles exhibit NIR emission at 984 nm under 850 nm excitation with full width at half maximum of 44.5 nm. Meanwhile, the janus nanoparticles showed catalytic degradation of organic dyes methyl blue and the blue color of methyl blue solution would fade gradually after addition of aqueous janus nanoparticles. This facile methodology for synthesis of Ag2S/Ag janus nanoparticles may be generally expanded to fabricate other janus nanocrystals. And the as-ordered Ag2S/Ag janus nanoparticles have the NIR-FL signals and catalytic decomposition properties, which have the potential to construct multi-mode, multi-signal and multi-functional application platform.