Synthesis Of Metal Doped Carbon Nanomaterials And Study Of Their Photo-/Electro-catalytic Properties

Energy plays a vital role in human’s activity.The exploration and utilization of new energy becomes more and more important due to the lack of energy. Hydrogen and oxygen from water are considered as highly efficient energy, which is one of available methods to relieve energy crisis. However, the efficiency of catalyst is too low. So the design and fabrication of efficient catalyst is a significant topic to develop new energy and relieve energy crisis. Carbon nanomaterials have received numerous attentions based on abundant source, low cost and low toxicity. As member of carbon nanomaterials, carbon dots have been applied in various photo- and electric-related fields due to their high solubitity, robust chemical inertness, easy functionalization and distinctive photo properties. This paper introduces preparation of Ag nanoparticle/carbon dots composite(Ag/CQDs), Co and N codoped carbon nanomaterial(Co/N/C) and Ni nanoparticle/carbon dots composite(Ni/CQDs). The structures of these materials were characterized with various instruments. Besides, thephoto-/electro-catalytic activity and corresponding catalytic mechanism of these materials were also studied. The detailed contents are shown as follows:(1) The Ag nanoparticle/carbon dots composite(Ag/CQDs) were synthesized by a simple chemistry method from AgNO3 and CQDs. The structure of Ag/CQDs was characterized by transmission electron microscopy, X-ray diffraction, Raman, UV-Vis and X-ray photoelectron spectroscopy methods. Catalytic activity of Ag/CQDs was investigated with TBHP as oxidant at 60 °C. Ag/CQDs showed efficient catalytic activity for the oxidation of cyclohexane. It was demonstrated that the conversion of cyclohexane reached up to 58.9% and the selectivity to cyclohexanone achieved 84.6%. Furthermore, it was also demonstrated that the excellent photocatalytic activity was attributed to the synergistic effects of Ag nanoparticles(NPs) and CQDs.(2) The porous Co, N codoped carbon nanomaterials(Co/N/C) were synthesized by a facile one-step pyrolysis of vitamin B12(VB12) and CQDs. Varying the initial mass ratio of CQDs and VB12 lead to controllable concentrations of Co and N after pyrolysis. The porous and crystalline structure of Co/N/C was characterized by high resolution transmission electron microscopy, Brunauer–Emmett–Teller(BET), X-ray diffraction, and X-ray photoelectron spectroscopy methods. Catalytic activity of Co/N/C for oxygen reduction reaction(ORR) was investigated. The Co/N/C exhibited efficient catalytic activity for ORR in both acid(0.1 M HClO4) and alkaline electrolyte(0.1 M KOH). Especially, the Co/N/C with 1.12% Co and 2.92% N prepared at 700 °C(Co1.12/N2.92/C-700) showed the highest catalytic activity.(3) Nickel nanoparticle/CQDs hybrid(Ni/CQDs) was prepared by the pyrolysis of Ni(OH)2/CQDs. The successful fabrication of Ni/CQDs was characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy instruments. Ni/CQDs showed efficient catalytic activity for hydrogen evolution reaction(HER) under strong alkaline condition(1 M KOH). Besides, the catakytic activity of Ni/CQDs can be further enhanced under light.