Study On Micro, Macro Regulations Of Graphene Based Materials And Their Applications In Energy Related Devices

Graphene layer has special properties, which is not mean high performance the devices composed by graphene will own. Using graphene sheets as building blocks, micro and macro regulations, and function research were carried out to provide a theoretical principle and experimental basis for seeking advanced materials for energy storage and conversion. Firstly, the micro regulation of graphene based materialsThe micro regulation(intrinsic regulation) of graphene is achieved by changing chemical environment of carbon atoms, yielding different functions from the original graphene. The methods include doping of heteroatoms, the controlling of graphene size and defects.1. The new type of N,S co-doped nanocomplexes of branched graphene nanocapsules has been fabricated by partially peeling the multi-walled graphitic capsules. Since the abundant edges and defects on the in-situ induced graphene sheets and capsule walls, the N,S co-doping, and the remained conductivity of the inner walls,the sample exhibits high reversible capacity, outstanding rate capability and long cyclic stability, promising as an advanced anode material in lithium-ion batteries(LIBs).2. We have successfully prepared a highly nitrogen-doped graphene-like capsule with three-dimensional(3D) interconnected porous structure. The large surface area and high-level nitrogen doping make the sample have good oxygen reduction reaction(ORR) performance, and as an advanced anode material in LIBs. Furthermore, we successfully developed a facile and scalable approach for hierarchical-structure nitrogen-rich hybrid porous graphen-like capsules with bamboo-like carbon nanotube whiskers grown in situ. The specifically designed sample combines the advantageous features of high surface area, abundant active sites and easy access to medium and rapid mass transport. As a result, they show very highperformance towards ORR and in LIBs. Secondly, the micro regulation of graphene based materialsGraphene fibrous structure owns features of light weight, flexibility, and easy to be functionalized. The 3D graphene with the porous network, usually has the characteristics of good conductivity, large specific surface area, and compressibility. Thus, effective assembly of one-dimensional and three-dimensional graphene was carried out in-depth investigation.1. We have developed a new scalable approach with dual geometric confinement to prepare meter-long graphene microtubings(μGTs) with a tunable diameter. The uniqueness of μGTs includes lightweight, high strength, conductivity, and flexibility. The as-prepared μGTs can be shaped to hierarchical multichannel fashion, andthe site-specific outer-wall, inner-wall, outer/inner-wall, and within-wall functionalization of μGTs are available.2. A general method of substrate-assisted reduction and assembly of graphene oxide(GO) has been developed for spontaneous deposition of 3D graphene network on arbitrary conductive substrates. This process offers a facilebut efficient approach for constructing a variety of unique graphene assemblies of practical importance. Thirdly, 3D assembly graphene sheets with designed compositions1. We have further developed an approach of "dual substrate-assisted reduction and assembly" for the synthesis of 3D functionalized graphenes with metal-based nanocomponents. Initially, GO spontaneous deposited on an active metal substrate. Then, active substrates(Sub0) are further oxidized to Subn+ ions with electron loss, while metal ions(Mm+) in the solution are reduced to the corresponding metal(M) by electron reception though the graphene sheets, thus the metal species spontaneously grow on the 3D graphene sheets in situ. For active metals, they are ready to be oxidized to M2 Om partially or completely, allowing the formation of M/M2 Om hybrids or M2 Om. If the different metal ions in the solution have close redox potentials, alloys could be obtained. The uniquely functionalized 3D graphene are promising for the potential application in the fields of energy conversion and storage.2. Design and synthesis of nanohybrids(Pt/PdCu nanoboxes, ternary Pd2/Pt Fe networks, graphitic C3N4-Pt nanohybrids) with low Pt loading anchored on 3D graphene framework, and the study of these materials as high-performance electrocatalysts for the oxidation of fuel molecules. The synergetic function between Pt and other ingredients in the nanohybrids, plus the conductive 3D graphene network support provide the fuel molecules good accessibility to the active sites, the obtained catalyst exhibits excellent electrocatalytic performance. Furthermore, we have prepared unique PdCu nanocapsules with controlled sizes on 3D graphene. After activation process, the catalyst presents much better electrocatalytic performance towards ethanol oxidation than commercial Pt/C catalyst.