Preparation Of Novel Nobel Metal Nanocrystals And Their Applications In Surface Enhanced Raman Scattering And Catalysis

In recent years,noble metal nanocrystals have been widely applied in biotechnology.nanopharmaceuticals,catalysis,and energy conversion due to their unique physical and chemical properties.In gernal,nanocrystals with different morphologies,compositions or structures exhibit various properties.In this thesis,we employed two approaches to synthesize two kind of noble metal nanoparticles with special morphologies and then further investigated their applications in surface-enhanced Raman scattering(SERS)and ethanol electrooxidationSystem ?:we reported a facile and robust approach for fabricating concave AuBPs(CAuBPs)with multiple high-index facets which are distinct from the conventional AuBPs and nanojavelins structures.We used the conventional AuBPs as seeds,which evolved into CAuBPs upon overgrowth in the presence of HAuCl4,Ag+ and CTBAB.The length of as-preapred CAuBPs can even extend up to 800 nm.The CAuBPs nanoparticles exhibit strikingly pronounced broader plasmonic tuning range(even exceeding 2000 nm).In addition,the SERS performance of CAuBPs improved with the size of CAuBPs increasing,which is mainly attributed to the increased "hot spots" areas on the larger CAuBPs.System ?:the calculated and experimental extinction spectra showed that the surface concavity significantly red-shifted both the longitudinal and transverse plasmon resonances.The especially wide plasmon resonance broadens the promising applications of CAuBPs in optoelectronic areas.FDTD simulation also demonstrated that the improved electric-field enhancements of CAuBPs at its apexes and edges are higher than those of AuBPs.Therefore,the concavity of CAuBPs endows them with higher near-field electromagnetic enhancements and much more exposure of denser uncoordinated atoms,leading to superior SERS and catalytic activities in comparison with AuBPs..System ?,we reported a 2D PdAg dendritic nanosheet that was prepared through co-reduction of the metal precursors in the present of certain surfactant at room temperature,which is distinctively different from previous systems.Octadecyltrimethylammonium chloride(OTAC)plays a crucial role in the synthesis of PdAg nanosheet.The carbochain length of surfactant-mediated transformation from 3D to 2D structure was observed.The prepared PdAg dendritic nanosheets after being loaded with carbon nanocubes showed superior catalysis of ethanol electrooxidation due to the special conjunct effects of alloys,nanosheets and dendritic structures.