In the last decades several new nanostructures of carbon have been discovered, including carbon nanotubes (CNTs), and the recently discovered 2-dimensional graphene. These new materials exhibit extraordinary and unique properties—making them extremely interesting both for fundamental science and for future applications. It is, however, of crucial importance to develop new and improved fabrication and processing methods for these carbon nanomaterials. In this thesis the concept of applying solution chemistry and solution-based techniques to fabricate and to deposit graphene and other carbon nanomaterials is explored. An area-selective deposition method was developed for CNT and carbon-coated iron nanoparticles. By utilizing organic functionalization the properties of the nanomaterials were tuned, with the purpose to make them soluble in a liquid solvent and also enable them to selectively adsorb to non-polar surfaces. The first step of the functionalization process was an acid treatment, to introduce defects in the materials. This method was also used to create defects in so-called carbon nanosheets (CNS). The effect of the defect formation on the electric properties of the graphene-like CNS was studied; it was found that the resistance of the CNS could be reduced to 1/50 by acid treating of the sample. Also, the effect of the created defects on gas adsorption to the surface of the CNS has been investigated. This was done using atomic layer deposition (ALD) of TiO2 on the CNS, and a clear change in nucleation be-havior was seen due to the acid-treatment. Furthermore, a solution-based new method for fabrication of graphene was developed; this method combines intercalation of bromine into graphite with ultrasonic treatment to exfoliate flakes into a solvent. From the solvent the flakes can be deposited onto an arbitrary substrate. Several important parameters in the method were investigated in order to optimize the process. One important parameter proved to be the choice of solvent in all steps of the procedure; it was shown to influence sonication yield, flake size, and deposition results. Toluene was identified as a suitable solvent. A mild heat-treatment of the starting material was also identified as a way to increase the exfoliation yield. Using this method, fabrication of few-layer graphene sheets was achieved and areas down to 3 layers in thickness were identified—this is in the very forefront of current solution-based graphene fabrication techniques.

In order to improve the performance and fundamental understanding of conducting polymers, development of new nanotechnologies for engineering aggregated states and morphologies is one of the central focuses for conducting polymers. In this work, we demonstrated an interfacial engineering method for the rational synthesis of a two-dimensional (2D) polyaniline (PANI) nano-array and its corresponding nitrogen-doped porous carbon nanosheets. Not only was it easy to produce a sandwich-like 2D morphology, but also the thickness, anchored ions and produced various metal phosphides were easily and rationally engineered by controlling the composition of the aqueous layer. The novel structural features of these hybrids enabled outstanding electrochemical capacitor performance. The specific capacitance of the as-produced diiron phosphide embedded nitrogen-doped porous carbon nanosheets was calculated to be as high as 1098 F g−1 at 1 A g−1 and an extremely high specific capacitance of 611 F g−1 at 10 A g−1, outperforming state-of-the-art performance among porous carbon and metal-phosphide-based supercapacitors. We believe that this interfacial approach can be extended to the controllable synthesis of various 2D material coupled sandwich-like hybrid materials with potential applications in a wide range of areas.

The synthesis of crystalline two-dimensional (2D) covalent organic frameworks (COFs) with fully unsaturated carbon–carbon backbones via a solution approach remains a great challenge. In this work, we report the first example of an olefin-linked 2D conjugated COF using a Knoevenagel polycondensation reaction of 1,4-phenylene diacetonitrile and three armed aromatic aldehyde. The resulting 2D poly(phenelyenevinylene) framework (2DPPV) possesses a sheet morphology, and a crystalline layered structure featuring a fully sp2-bonded carbon skeleton with pendant cyanide groups. Its unique alternating structure with a serrated configuration has been essentially evaluated using HR-TEM TEM analysis, nitrogen physisorption measurements, PXRD studies and theoretical simulations. Upon thermal and activation treatments, the as-prepared 2DPPV can be facilely converted into porous carbon nanosheets with large specific surface areas of up to 880 m2 g−1 which exhibit an excellent electrochemical performance as supercapacitor electrodes and electrocatalysts for the oxygen reduction reaction. This represents an economic non-template approach to 2D porous carbon materials for energy-related applications.

The synthesis of crystalline two-dimensional (2D) covalent organic frameworks (COFs) with fully unsaturated carbon–carbon backbones via a solution approach remains a great challenge. In this work, we report the first example of an olefin-linked 2D conjugated COF using a Knoevenagel polycondensation reaction of 1,4-phenylene diacetonitrile and three armed aromatic aldehyde. The resulting 2D poly(phenelyenevinylene) framework (2DPPV) possesses a sheet morphology, and a crystalline layered structure featuring a fully sp2-bonded carbon skeleton with pendant cyanide groups. Its unique alternating structure with a serrated configuration has been essentially evaluated using HR-TEM TEM analysis, nitrogen physisorption measurements, PXRD studies and theoretical simulations. Upon thermal and activation treatments, the as-prepared 2DPPV can be facilely converted into porous carbon nanosheets with large specific surface areas of up to 880 m2 g−1 which exhibit an excellent electrochemical performance as supercapacitor electrodes and electrocatalysts for the oxygen reduction reaction. This represents an economic non-template approach to 2D porous carbon materials for energy-related applications.

In order to improve the performance and fundamental understanding of conducting polymers, development of new nanotechnologies for engineering aggregated states and morphologies is one of the central focuses for conducting polymers. In this work, we demonstrated an interfacial engineering method for the rational synthesis of a two-dimensional (2D) polyaniline (PANI) nano-array and its corresponding nitrogen-doped porous carbon nanosheets. Not only was it easy to produce a sandwich-like 2D morphology, but also the thickness, anchored ions and produced various metal phosphides were easily and rationally engineered by controlling the composition of the aqueous layer. The novel structural features of these hybrids enabled outstanding electrochemical capacitor performance. The specific capacitance of the as-produced diiron phosphide embedded nitrogen-doped porous carbon nanosheets was calculated to be as high as 1098 F g−1 at 1 A g−1 and an extremely high specific capacitance of 611 F g−1 at 10 A g−1, outperforming state-of-the-art performance among porous carbon and metal-phosphide-based supercapacitors. We believe that this interfacial approach can be extended to the controllable synthesis of various 2D material coupled sandwich-like hybrid materials with potential applications in a wide range of areas.