This article introduces our group’s recent study on a new strategy that uses amorphous conjugated polymer networks (CPNs) to develop functional nanocarbons as structural analogs of graphene and graphene oxide. Amorphous CPNs are usually synthesized by the simultaneous random copolymerization of multiple conjugated monomers, such as redox-active molecules. In amorphous CPNs, the functional unit molecules are dispersed in the network without aggregation, whereas rigid assemblies are formed in conventional main- and side-chain polymers and metal- and covalent-organic frameworks. This new state of assembly of functional molecules has structural flexibility which is advantageous for their functionalization. Because the amorphous CPNs are obtained in stacked layers, nanosheets are obtained by exfoliation. A systematic screening of the monomers was conducted based on data provided by artificial intelligence-assisted data analysis. We have reported the electrochemical uses of the amorphous CPNs containing quinone derivatives. Their excellent electrochemical performance, such as catalytic activity for the hydrogen evolution reaction and charge capacities for supercapacitors and batteries, are due to their nanostructures of the amorphous CPNs. When the conjugated networks are expanded using monomers rich in conjugated moieties, the resultant CPNs can be considered amorphous graphene and graphene-oxide analogs that can be used to design and synthesis new nanocarbon materials.

The growing demand for point-of-care testing technologies has accelerated the development of rapid diagnostics that can be used outside clinical settings. Blood gas analyzers, commonly used in emergency care, assess respiratory and metabolic status using arterial blood. They provide real-time information on oxygenation (pO₂), ventilation (pCO₂), and acid-base balance. Modern systems also measure concentrations of electrolytes (e.g., Na⁺, K⁺, Ca²⁺, and Cl⁻), glucose, and lactate. As the range of analytes increases and healthcare increasingly shifts toward home and decentralized settings, there is a growing need for miniaturized, low-cost, and reliable electrochemical sensors. However, miniaturization is hindered by key technical issues, including the lack of stable reference electrodes and interference issues in enzymatic glucose sensors that require complex structures and expensive Pt electrodes. We introduce graphene-coated porous silica spheres loaded with Prussian-blue (PB/G/PSS) as a versatile material platform to solve these problems. Because of the extremely low solubility of PB, PB/G/PSS serves as a stable and reliable reference electrode for miniaturized oxygen sensors. In addition, the unique electrochemical activity of Prussian blue, with a hydrogen peroxide reduction potential positioned between the oxidation potential of ascorbic acid and the reduction potential of oxygen, enables PB/G/PSS to function effectively as a working electrode even in the presence of interfering species.

In this thesis, design guidelines for precursor molecules used in the synthesis of functional carbon materials were established. Precursor molecules were systematically designed and synthesized to develop carbonaceous materials with tailored structures and properties. The applications of the resulting porous carbons as catalysts and catalyst supports were also extensively investigated.

Carbon materials, owing to their diverse structures and unique physicochemical properties, play a crucial role in realizing a sustainable society. Solid-state nuclear magnetic resonance (NMR) is a powerful tool for investigating the structures of carbon materials, as well as the states of atoms and molecules within them. However, the potential of solid-state NMR in carbon materials research has not been fully realized due to several inherent difficulties. The aim of this thesis is to develop and apply advanced solid-state NMR techniques for carbon materials research. In Chapter 2, dynamic nuclear polarization (DNP)-NMR was applied to achieve highly sensitive and accurate analysis of carbon surface functional groups. In Chapter 3, the effects of heteroatoms doped into carbon materials on sodium storage were investigated using multiple techniques including solid-state NMR. In Chapter 4, the first observation of the ³⁹K NMR signals in potassium-graphite intercalation compounds (K-GICs) was demonstrated. Collectively, these results contribute to the development of analytical methods and deeper understanding of phenomena in advanced carbon materials.