Surface Modification Of Two Dimensional Nano-materials And Its Application In Electrocatalysis

With the development of science and technology, electrochemistry as a classic discipline shows more and more prominent contribution in the real life. The problems that electrochemical studies on constitutes an important means to solve the current world energy crisis and the problem of environmental pollution. In a conventional electrode reaction, hydrogen evolution reaction, oxygen reduction reaction and the methanol oxidation reaction are all important chemical electrode reactions among water splitting devices and fuel cells and other clean energy technologies. However, the precious metal platinum, with its excellent performance as catalyst in these three reactions, has restricted the applications of water splitting and fuel cells due to the high cost. With the development of nanomaterials in recent years, two-dimension nanomaterials, with its unique electrical, optical, magnetic properties and unique structural advantages, has brought new hope for materials design in the field of energy. Two-dimension nanomaterials provide not only the direction for exploring new electrocatalyst and energy storages, but also a new platform for function oriented of material design and performance optimization.In this paper, by means of analyzing constraints of electrochemical catalyst performance, taking the nature of the material itself as the start point, we aimed at designing functionalized two-dimension nanomaterials to improve the electrocatalytic performance and further realized the preparation of high efficient electrochemical energy conversion and energy storage. The author has optimized and upgraded systematically molybdenum sulfide and graphene through defect engineering and element doping to access a high-performance oxygen reduction reaction (ORR), hydrogen evolution reaction (HER) and the methanol oxidation reaction (MOR). This paper provides a new sight to the functional design of two-dimensional nanomaterial as well as to research design and preparation of future high-performance electrochemical catalyst. By the way, this paper mainly includes the following three parts:(1) Molybdenum disulfide (MoS2), as a potential material for catalyst of HER, has a restricted catalytic properties due to its poor conductivity and less catalytic active sites. Based on these considerations, the author uses, for the first time, the low-temperature plasma to create defects and dope oxygen atoms in MoS2 film electrode. Defect rich structure of the material make the active sites increase significantly. In addition, the doping of oxygen reinforces the electrical conductivity of MoS2. Catalytic properties of MoS2 film electrode have been significantly improved after argon and oxygen plasma treatment.(2) Based on the knowledge that the ORR catalytic performance at the edge of the graphene is better than that on the surface, the author, by using of high temperature plasma, designed and fabricated for the first time defect-rich undoped graphene on the surface. The defects of prepared graphene on the surface make itself maintain the intact overall structure, as well as a good electrical conductivity. Meanwhile, taking advantage of the structure of the material makes the graphene fully exposed active sites. After defect engineering, this new defect-rich graphene exhibits a very low onset potential, and maintaining a large current density to achieve a significantly improved catalyst performance.(3) Platinum is one of the ideal catalysts for the MOR, but the high price and low poisoning resistance has restricted its development. This paper, making use of nitrogen-doped graphene as a carrier to support platinum nanoparticles, describes the successful preparation of catalyst with superior performance for methanol oxidation. Compared to platinum catalyst loaded on traditional non-doped graphene, platinum catalyst loaded by nitrogen-doped graphene shows a better catalytic performance and better resistance to carbon monoxide poisoning.