Controlled Synthesis Of Gold Nanomaterials And Their Applications

Electrodeposition has attracted wide attention for it is a simple, feasible, green, and cost-effective method. The small molecules used as a growth directing agent to developed monometallic nanoparticles or bimetallic nanoparticles. To discuss how these nanoparticles are grew, we investigate the effect of electrochemical parameters, concentration of small molecules or the precursor concentration. The electrocatalytic behavior and SERS of the nanoparticles are investigated in same detail. The main contents of this thesis the following four parts:1. Au porous textile-like sheet arrays (AuPTSAs) have been facilely prepared on a glassy carbon electrode (GCE) by one-step electrodeposition, which are performed at-0.4V for600s in the electrolysis solution containing10mmol/L HAuCl4,1.25mol/L N-methylimdazole and0.5mol/L H2SO4. Thus prepared AuPTSAs are perpendicular to the electrode surface and growing in the (111) directions and their growth mechanism is discussed in some detail. The AuPTSAs show enhanced electrocatalytic activity with better stability toward methanol oxidation in alkaline media, compared with those of polycrystalline Au nanoparticles.2. Au nanodendrites were simply synthesized by one-step electrodeposition with the constant potential of-0.2V for900s in0.5mol/L H2SO4containing7.5mmol/L HAuCl4and150mmol/L L-asparagine, which were preferentially growing along the (111) directions. The as-prepared Au dendrites were used as highly active SERS substrates for highly sensitive detection of formaldehyde based on its reaction with4-amino-3-hydrazino-5-mercapto-1,2,4-triazol (AHMT). The formaldehyde sensor displayed a wide linear range from83.2to997.5nmol/L, with a low detection limit of7.2nmol/L (S/N=3).3. A simple, facile, controllable, and green one-step electrochemical co-deposition method was developed for the preparation of hierarchical wheat-like Au-Pd heterostructures on a glassy carbon electrode (GCE) without any template or surfactant, only using L-glutamic acid as a growth directing agent. Meanwhile, the electrochemical experiments demonstrate the superior electrocatalytic activity of the Au-Pd heterostructures toward methanol oxidation, achieving a maximum catalytic current density is45.8mA cm-2in the presence of0.5mol/L methanol, much larger than those on pure Au (5.4mA cm-2) or Pd (25.0mA cm-2) under the same conditions.4. The nano-thorn gold-platinum structures were constructed on a glassy carbon electrode (GCE) through one-step electrochemical reduction of HAuCl4and H2PtCl6in acidic media with the assistance of N-methylimdazole. It is found that the applied potential, the molar ratio of HAuCl4to H2PtCl6, electrodeposition time, and concentration of N-methylimdazole played an important role in the construction of nano-thorn gold-platinum structures and their growth mechanism was discussed in some detail. Meanwhile, the nano-thorn gold-platinum structures show enhanced electrocatalytic activity with better stability toward ethylent glycol in alkaline media, compared with those of polycrystalline Au nanoparticles and Pt nanoparticles.