Preparation And Characterization Of Gold-based Nanomaterials

The significant size effect of gold-based nanomaterials makes it unique photoelectric and catalytic properties,which can be widely used in the field of biomedical,energy and chemical industry.The potential value of gold based nanomaterials is systematically explored based on Au nanoparticles in the paper.Compared with bulk gold,hollow gold spheres have great application prospects in photoelectric catalysis and photothermal therapy,but the current preparation routes have disadvantages such as low atomic utilisation,small scale and tedious steps.Therefore,we developed a synthetic route to prepare hollow gold spheres,and regulated its morphology to investigate its influencing factors.In addition,Au exsits a compensation effect when alloyed with early transition metals.The controllable preparation,structural composition and dimensional morphology of Au-Ti alloy nanoparticles have been thoroughly investigated using inexpensive Ti as the alloying element.The results obtained confirm that the introduction of Ti element into Au-based alloys can substantially increase their catalytic activity,which is also consistent with the predictions of the Trasatti model for the HER performance of alloyed catalysts,further demonstrating that early transition elements have a very significant enhancement effect on gold-based catalysts.The first part of the work in this thesis is to prepare hollow gold spheres by rapid heating-cooling method on the basis of preparing Au nanoparticles by wet chemical method.The effects of different supports,driving currents,durations and climbing/cooling times on the microstructure of gold hollow spheres were investigated.The results show that gold hollow spheres can be prepared by using lithium naphthalene-treated carbon supports as support carriers with a drive voltage of30 V,a drive current of 35 A,a duration of 20 s and a creep time of 2 s during the rapid heating-cooling process.The method has the advantage of template-free,solvent-free and time-saving.This work provides some reference value for the simple and rapid synthesis of hollow structural materials.In the second part of this thesis,Au-Ti alloy nanoparticles were successfully prepared by pressure co-reduction method.The effects of experimental methods,surfactants,reaction pressure and supporting supports on the microstructure of the samples were investigated.The results show that when the concentration of Au³⁺in the precursor solution is 0.0033 M,the concentration of Ti⁴⁺is 0.0008-0.0033 M,the black carbon support treated with naphthalene lithium was used as the support carrier,and the reaction pressure is 0.5 MPa,the series of Au Ti alloy nanoparticles with good dispersion,narrow particle size distribution and size of 7-9 nm can be prepared.When Ti⁴⁺concentration is 0.0008,0.0011,0.0016 and 0.0033 M,Au-Ti alloy nanoparticles with atomic ratio of 1.21:1,2.36:1,3.24:1,4.14:1 can be prepared.The results of electrocatalytic hydrogen evolution performance test show that when the atomic ratio of Au to Ti is 1.21:1,Au-Ti alloy nanoparticles have the best catalytic activity in 0.5M H₂SO₄solution,and the catalytic activity of Au-Ti alloy nanoparticles with different Ti doping amount is better than Au under alkaline condition(1 M KOH solution).