Synthesisand Electrochemical Properties Of Nanohybrid Systems Based On Two-dimensional Materials

After ten-years intense research,two-dimensional(2D) materials represented by single-layer graphene have achieved essential and comprehensive progresses. Meanwhile, the concept of 2D materials also has been permeated into many research fields. Currently, the design and synthesis of hybrid materials based on 2D materialsrepresents a very important research direction in this field. The development of hybrid materials based on 2D materialscan not only contribute todeep understanding theirphysical and chemical properties, but also expend the application range of both 2D materials and hybridizedproperties materials. Aimed at several important electrochemical processes related to energy and environmental fields, this dissertation focuses ondevelopingsame new synthetic methods to construct novel hybrids structures based on 2D materials, and also utilizing the advantages of 2D materials to realize superior electrochemical properties of hybridsystems, more details is as follows:1. Non-Pt noble metal clusterslike Au clusters are believed to b e promisinghigh performance catalysts for the oxygenreduction reaction(ORR) at the cathode of fuelcells, but they still suffer big problems duringthe catalysis reactions, such as a large amountof the capping agents being on the surface andeasy occurrence of dissolution and aggregation.To overcome these obstacles, here, a novel and general strategy was developed to grow ultrafine Au clusters and other metal(Pt, Pd) clusters onthe reduced graphene oxide(r GO) sheets without any additional protecting molecul e orreductant. Compared with the currently generally adopted nanocatalysts, the as-synthesized Au cluster/r GO hybrids display an impressive eletrocatalyticperformance toward ORR, for instance, high onset potential, superior methanol tolerance, and excellent stability.2. In order to get high performancecapacitive deionization(CDI) electrode materials, a novel, simple and versatile methodwas developedto fabricate three dimensional(3D) graphene/metal oxide(including Ti O 2, Ce O2, Fe2O3, and Mn3O4) nanoparticle(NP)hybrids, using lowvalence metal ions as the precursors. Impressively, with respect to three important parameters ofthe CDI process, electroabsorption capacity, rate and reversibility, the GA/TiO2 hybrids outperform the currently reportedmaterials. It is expected that this work not onlyoffers a promising way to develop high effective CDI electrodematerials, but also holds the potential to be applied in otherareas such as supercapacitors, catalysis and newly-emerged ―capacitive mixing‖ technique.3. Design and synthesis of effective electrocatalysts for hydrogen evolution reaction in alkalineenvironments is critical to reduce energy losses in alkaline water electrolysis. A hybrid nanomaterial comprising of one-dimensional ultrathin platinum nanowires grown ontwo-dimensional single-layered nickel hydroxide was successfullysynthesized. Judicious surface chemistry to generate thefully exfoliated nickel hydroxide single layers is explored to be the key for controllable growthof ultrathin platinum nanowires with diameters of about 1.8 nm. Impressively, this hybridnanomaterial exhibits superior electrocatalytic activity for hydrogen evolution reaction inalkaline solution, which outperforms currently reported catalysts, and the obviously improvedcatalytic stability. This work may lead towards the development of singlelayeredmetal hydroxide-based hybrid materials for applications in catalysis and energyconversion.