The Preparation Of Dye Molecules Functionalized Graphene Nanocomposites And Its Application In Photocatalytic Hydrogen Production

With the shortage of fossil energy and the pollution of the environment becoming more seriously, Human society are looking for new energy to add or replace the normal energy. Solar energy canbe transformed to hydrogen energy by photocatalysis for water splitting. There are several advantages of the hydrogen energy which is a clean, efficient, high calorific value, and environmentally friendly. Hence, the use of the solar energy photocatalysis is an advanced potential technique to convert solar energy into chemical energy and has many advantages in energy conversion. Photocatalytic water splitting to generate hydrogen has attracted much attention, and is developing rapidly.In this paper we use graphene as substrate material. A series of functionalized graphene nanocomposites were prepared via covalent and non-covalent functionalization. This nanocomposites were characterized and using the nanocomposites as photocatalyst for water splitting. Some corresponding researches were done as follows:(1) A new type of graphene-based nanohybrid was prepared from graphene nanosheets and triphenylamine (TPA-CHO) through1,3-dipolar cycloaddition. The nanohybrid was modified by platinum nanoparticles via photodeposition. The nanohybrid structurewere characterized by AFM, SEM, TEM, Raman, FTIR. The results of fluorescence quenching and photocurrent enhancement of the triphenylamine functionalized graphene revealed that photoinduced electron transfer from triphenylamine moiety to the graphene sheet. Under irradiation of UV-vis light, hydrogen was produced from photodecomposition of water using Pt/G-TPA nanohybrid as the catalyst in the presence of KI. The catalytic activity of Pt/G-TPA nanohybrid was influenced by the pH value and we investigated the stability of catalyst. According to the experimental results, we explain the mechanism of hydrogen evolution over Pt/G-TPA photocatalyst.(2)5,10,15,20-tetrakis(4-(hydroxyl)phenyl) porphyrin (TPPOH) functionalized reduced graphene oxide (RGO) was prepared through non-covalent interaction. RGO nanosheet and Pt/RGO have been successfully prepared with chemical reduction and the structure of the nanocomposite was characterized with AFM, XPS, XRD, FTIR, TEM and Raman, respectively. The results of fluorescence quenching and photocurrent enhancement of the RGO-TPPOH revealed that photoinduced electron transfer from TPPOH moiety to RGO sheet. Under irradiation of UV-vis light, hydrogen was produced from photodecomposition of water using Pt/RGO-TPPOH nanocomposite as the catalyst in the presence of TEA. With the help of surfactant Cetrimonium Bromide (CTAB), it can enhance the stability of catalyst. The catalytic activity of Pt/RGO-TPPOH nanocomposite was influenced by the pH value, the ratio of RGO/TPPOH and the amount of Pt nanoparticles. According to the experimental results, we explain the mechanism of hydrogen evolution over Pt/RGO-TPPOH photocatalyst.(3) TiO2-graphene nanocomposite (TiO2-G) and TiO2/pyrenesulfonic acid-graphene (TiO2-PSA-G) were prepared through photoreduction graphene oxide (GO) in the methanol solution. Those nanohybrids were modified by platinum nanoparticles via photodeposition. The nanohybrid structure and morphology were characterized by SEM, XRD, Raman, FTIR. Under irradiation of UV-vis light, hydrogen was produced from photodecomposition of water using Pt/TiO2-G and Pt/TiO2-PSA-G nanocomposite as the catalys, respectively. The catalytic activities of Pt/TiO2-G and Pt/RGO-TPPOH nanocomposite were influenced by pH value, the amount of graphene and the PSA molecular. According to the experimental results, we explain the mechanism of hydrogen evolution over Pt/TiO2-G and Pt/TiO2-PSA-G photocatalyst respectively.