Preparation And Electrochemical Behavior Of Graphene-Au, Pt Nanoassemblies

In the last few decades, the use of solar energy has received more and more attention. At present, the research about the use of solar energy is focused on the use of photocatalytic hydrogen production and solar cells. Among them, graphene/metal nanomaterials have excellent solar energy conversion properties due to their excellent optical and electron transfer properties. It is considered as a functional material with wide application prospect. But the electron transfer in the system and its influencing factors are not clear. So that, the graphene/Au, Pt nanomaterials were prepared, and their photoelectric chemical behavior and influencing factors were systematically studied. On this basis, the synergistic effect and mechanism of Eosin Y and Rhodamine B were detail discussed in the graphene/Pt nanomaterials. The specific research contents and results are as follows:1. The graphene/Au nanoparticle electrode was constructed by layer by layer self-assembly technique, and its morphology, optical properties and electrochemical properties were characterized. Subsequently, the photoelectrochemical behavior of the electrode and the effect of pH, Au nanoparticle size, the loading capacity and other factors on the photoelectrochemical behavior of the electrode were investigated. The results show that the photoelectric response of graphene/Au nanoparticle electrode is 5 times as much as that of the graphene electrode. Moreover, with the size of the loading of Au nanoparticles becomes smaller, the photoelectric response intensity of graphene/Au nanoparticle electrode increases continuously. When using different wavelengths of monochromatic light source, we find that with the excitation light wavelength increases, the graphene/Au nanoparticles electrode photoelectric response intensity gradually weaken, but the photoelectric response relative strength of the graphene/Au nanoparticle electrodes and pure graphene electrode is gradually increased. The reason of the results is that the ability of Au nanoparticles to capture visible light is stronger than that of graphene. And the larger the excitation wavelength, the greater the difference between the Au nanoparticles and graphene. These experimental results provide a theoretical support for the application of graphene based materials in the field of photocatalytic hydrogen production and solar cells.2. Graphene/Pt nanoparticle electrode was prepared by situ photoreduction method. The morphology and optical properties of the system were also characterized. Subsequently, the photoelectrochemical behavior of the electrode and the effect of pH, Pt loading capacity and the photoreduction degree of RGO were investigated. In addition, the effect of the metal species on the photoelectrochemical behavior of graphene was discussed. The results show that the photoelectric response of graphene/Pt nanoparticle electrode is 5.9 times of the pure graphene electrode. Comparing with the graphene/Au nanoparticles, we found that the Pt nanoparticles have a similar effect on the photoelectrochemical behavior of graphene with Au nanoparticles. But the effect of Pt nanoparticles on graphene was greater than the Au nanoparticles. The reason for this result may be that the work function of Pt is larger than Au, so it is more favorable for the migration of the optical electron.3. A photoelectrochemical system containing Eosin Y, Rhodamine B and the graphene loaded with Pt nanoparticles was fabricated. And the synergistic effect between Eosin Y and Rhodamine B was explored using photoelectrochemical technique. The results show that there exists obvious synergistic effect between Eosin Y and Rhodamine B in the as-fabricated photoelectrochemical system. Compared with the photoelectrochemical systems only containing Eosin Y or Rhodamine B, the photoelectrochemical system containing Eosin Y and Rhodamine B exhibits higher photoelectrochemical response. When the graphene loaded with Pt nanoparticles is cosensitized by Eosin Y and Rhodamine B, the photocurrent is about 71% higher than the sum of the photocurrents of the photoelectrochemical system containing Eosin Y and the photoelectrochemical system containing Rhodamine B. This synergistic effect may be ascribed to the energy transfer from Eosin Y to Rhodamine B under irradiation. Herein, the Pt nanoparticles play an important role in the photovoltaic performance. The synergistic effect between Eosin Y and Rhodamine B cannot be observed if the Pt nanoparticles are absent. Moreover, the synergistic effect was investigated as a function of pH, content of Pt, molar ratio of Eosin Y to Rhodamine B, and total concentration of Eosin Y and Rhodamine B, respectively.