The inclusion of atoms other than carbon into the framework of polycyclic conjugated hydrocarbons can have profound effects on the properties of the resultant compounds. Substitution of acenes with nitrogen-, oxygen-, and sulfur-containing rings has long been used as a strategy to alter the HOMO and LUMO energy levels of a compound and direct the solid-state morphology. In this thesis, I present my work in extending heteroatom substitution into the class of compounds known as indenofluorenes. Chapter I serves as an overview of indenofluorenes and related compounds with a special focus on the redox properties of these materials. Chapter II covers the synthesis and characterization of two selenophene-containing indenofluorene analogues. Chapter III discloses a new synthetic method for the preparation of unsymmetrical indenofluorenes and discusses the unusual reactivity of the dione precursors. Chapter IV is a comprehensive study of indacenodibenzothiophenes. This chapter investigates how heteroatom substitution affects the antiaromaticity of the indacene core and presents a detailed optoelectronic, computational, solid-state and materials study of a series of indacenodibenzothiophene derivatives. Chapter V presents my work towards the synthesis of the final unknown indenofluorene isomer, indeno[1,2-a]fluorene. Appendices A and B discuss my work done as part of Professor Shih-Yuan Liu’s research group at the start of my graduate career. This dissertation includes previously published and unpublished coauthored material. / 10000-01-01

Tübingen, Univ., Diss., 2008.

Ultramicroelectrodes (UMEs) are generally defined as electrodes with sizes ≤25 µm. UMEs can be prepared by several methods including by sealing a conductive filament like thin metal wire or a single carbon fiber in a glass capillary. The small size of UMEs makes them useful as probes for measuring electroactive species in confined spaces (for example, inside living cells, etc.), and also enables very effective mass transport, resulting in rapid achievement of steady-state response and facilitating measurement of fast electrochemical reactions. Application of UMEs often requires modification of the electrode surface to improve the selectivity and the sensitivity towards the target analyte. Surface modification methods are time-consuming and may require expensive equipment. Previous research in our group demonstrated that a simple soft nitriding method could be employed to introduce surface nitrogen on carbon fiber (CF). The technique improved electrochemical response of CF-UMEs towards hydrogen peroxide (a reactive oxygen species that has been related to various malignancies and disorders) and, in separate experiments, also enabled deposition of electroactive metal nanoparticles on the UME surface. Since the presence of phosphorus heteroatoms on carbon electrodes has been shown to impart similar benefits, here we investigate a simple phosphorus doping strategy to make P-doped CF-UMEs. We compare their properties towards the electrocatalytic reduction of H2O2 to both N-doped CF-UMEs and unmodified CF-UMEs.

Neste trabalho o carbono comercial Vulcan XC72 foi modificado com heteroátomos de N, S e P por meio do tratamento térmico a 800 °C com ureia, ácido sulfúrico e ácido fosfórico, respectivamente. Os carbonos modificados foram utilizados na preparação de eletrocatalisadores Pt/C e PtRu/C e aplicados na oxidação eletroquímica do metanol. Os materiais obtidos foram caracterizados por espectroscopia dispersiva de raios X, difração de raios X, espectroscopia Raman, microscopia eletrônica de transmissão e voltametria cíclica. A oxidação eletroquímica do metanol foi estudada por voltametria cíclica e cronoamperometria. Os espectros Raman mostraram que as razões de intensidades das bandas D e G dos suportes de carbono modificados com heteroátomos foram maiores que a observada para o carbono Vulcan XC72 sugerindo a incorporação na estrutura do carbono. As análises por difração de raios X mostraram para todos os eletrocatalisadores Pt/C a estrutura cúbica de face centrada (cfc) e as micrografias eletrônicas de transmissão que todos materiais apresentaram tamanhos de partícula na faixa 4-5 nm. Para os eletrocatalisadores PtRu/C preparados com os suportes de carbono modificados com N e S, os difratogramas de raios-X apresentaram apenas a fase Pt (cfc) não havendo deslocamento dos picos desta fase. Nestes materiais os picos referentes a fases de Ru não foram identificados sugerindo que o Ru apresenta-se como uma fase amorfa. Por outro lado, para o material modificado com P, observou-se um deslocamento dos picos da fase Pt(cfc) para ângulos maiores, sugerindo a formação de liga Pt-Ru e também foi observado a presença da fase Ru hexagonal compacta. Os eletrocatalisadores Pt/C e PtRu/C preparados com os suportes contendo heteroátomos apresentaram uma melhora significativa na atividade eletrocatalítica quando comparados aos materiais preparados com o suporte não modificado. A melhora na atividade pode estar relacionada a modificações na interação metal-suporte, bem como, as diferentes espécies Pt e Ru presentes no caso do eletrocatalisador PtRu/C preparado utilizando o suporte modificado com P. / In this work, commercial Vulcan XC72 carbon was modified with heteroatoms like N, S and P by thermal treatment at 800 ° C in the presence of urea, sulfuric acid and phosphoric acid, respectively. The modified carbons were used in the preparation of Pt/C and PtRu/C electrocatalysts and tested for methanol electro-oxidation. The materials were characterized by dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy and cyclic voltammetry. The methanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry. The Raman spectra showed that the intensity ratios of D- and G- bands of the carbon supports modified with heteroatoms were higher than that observed for Vulcan XC72 carbon suggesting the incorporation in the structure. X-ray diffraction analysis showed that Pt/C electrocatalysts have face-centered cubic structure (fcc) and transmission electron micrographs presented particle sizes in the range 4-5 nm. For PtRu/C electrocatalysts made with carbon supports modified with N and S, the X-ray diffraction patterns showed only the presence of Pt(fcc) phase with no shift of the Pt peaks. Peaks of Ru crystalline phases were not identified suggesting that in these materials Ru appears as an amorphous phase. On the other hand, for PtRu/C electrocatalyst prepared with carbon support modified with P, there was a shift of Pt(fcc) peaks to higher angles suggesting Pt-Ru alloy formation and the presence of Ru hexagonal close-packed phase was also observed. Pt/C and PtRu/C electrocatalysts prepared with carbon support modified with heteroatoms showed a significant improvement of electrocatalytic activity when compared to the unmodified material. The improvement in electrocatalytic activity can be related to changes in the metal-support interaction, as well as to the different Pt and Ru species for PtRu/C electrocatalyst prepared with carbon support modified with P.

The supercapacitor is one of the most important energy storage devices as its construction allows for addressing many of the drawbacks related to batteries, but the low energy density of current systems is a major issue. In this doctoral dissertation, with a view to attaining high energy density supercapacitor systems that can be comparable to those for batteries, new heteroatom-containing carbons in the form of particles and three-dimensional films were investigated. A nitrogen-containing material, acrodam, was chosen as the carbon precursor due to the inexpensiveness, high carbonization yield, oligomerizability, etc. The carbon particles were prepared from acrodam together with caesium acetate as a meltable flux agent, and disclosed excellent properties in hydroquinone-loaded sulphuric acid electrolyte with high energy densities (up to 133.0 Wh kg–1) and sufficient cycle stabilities. These properties are already now comparable to those of batteries. Besides, conductive carbon three-dimensional films were fabricated using acrodam oligomer as the precursor by the inexpensive spin coating method. The films were found to be homogeneous, flat, void- and crack-free, and high conductivities (up to 334 S cm–1) could be obtained at the carbonization temperature of 1000 ºC. Furthermore, a porous carbon three-dimensional film could be formed using an organic template at the first attempt. This finding demonstrates the film’s potentiality for various applications such as supercapacitor electrode; the essential absence of contact resistance within the network should contribute to effective transportation of electron within the electrode. The progress made in this dissertation will open a new way to further enhancement of energy density for supercapacitor as well as other applications that exceeds the current properties. / Der Superkondensator ist einer der wichtigsten Energiespeicher da seine Konstruktion die Lösung vieler Nachteile von Batterien erlaubt. Allerdings weisen derzeitige Systeme noch zu geringe Energiedichten auf. Um Superkondensatoren mit Energiedichten vergleichbar zu Batterien zu ermöglichen, wurden in der vorliegenden Dissertation neue, heteroatomhaltige Kohlenstoffe in Form von Partikeln und Filmen untersucht. Aufgrund geringer Kosten, hohen Ausbeuten, Polymerisierbarkeit usw. wurde die stickstoffhaltige Substanz Acrodam als Kohlenstoffvorstufe verwendet. Die Kohlenstoffpartikel wurden ausgehend von Acrodam zusammen mit Cäsiumacetat als schmelzbares Flussmittel hergestellt und wiesen ausgezeichnete Eigenschaften in Hydrochinon geladenen Schwefelsäure-Elektrolyten mit hohen Energiedichten (bis zu 133,0 Wh kg–1) und guten Zyklusstabilitäten auf. Diese Eigenschaften sind bereits jetzt vergleichbar mit denen von Batterien. Weiterhin wurden unter Verwendung von Acrodamoligomeren als Vorstufe und mit Hilfe der kostengünstigen Rotationsbeschichtung leitfähige, dreidimensionale Kohlenstofffilme hergestellt. Bei einer Karbonisierungstemperatur von 1000 °C konnten die Materialien als homogene, flache, Hohlraum-und Riss-freie Filme erhalten werden, die eine hohe Leitfähigkeit (bis zu 334 S cm–1) aufwiesen. Darüber hinaus konnte mit einem organischen Templat ein dreidimensionaler, poröser Kohlenstoff geformt werden. Dies zeigt das Potential der Filme für verschiedene Anwendungen wie Superkondensatorelektroden; die Abwesenheit von Übergangswiderständen im Netzwerk sollte zu einem effizienten Transport von Elektronen in der Elektrode beitragen. Die Ergebnisse dieser Dissertation werden neue Wege zur Verbesserung der Energiedichte von Superkondensatoren sowie weiteren Anwendungen eröffnen.

Neste trabalho o carbono comercial Vulcan XC72 foi modificado com heteroátomos de N, S e P por meio do tratamento térmico a 800 °C com ureia, ácido sulfúrico e ácido fosfórico, respectivamente. Os carbonos modificados foram utilizados na preparação de eletrocatalisadores Pt/C e PtRu/C e aplicados na oxidação eletroquímica do metanol. Os materiais obtidos foram caracterizados por espectroscopia dispersiva de raios X, difração de raios X, espectroscopia Raman, microscopia eletrônica de transmissão e voltametria cíclica. A oxidação eletroquímica do metanol foi estudada por voltametria cíclica e cronoamperometria. Os espectros Raman mostraram que as razões de intensidades das bandas D e G dos suportes de carbono modificados com heteroátomos foram maiores que a observada para o carbono Vulcan XC72 sugerindo a incorporação na estrutura do carbono. As análises por difração de raios X mostraram para todos os eletrocatalisadores Pt/C a estrutura cúbica de face centrada (cfc) e as micrografias eletrônicas de transmissão que todos materiais apresentaram tamanhos de partícula na faixa 4-5 nm. Para os eletrocatalisadores PtRu/C preparados com os suportes de carbono modificados com N e S, os difratogramas de raios-X apresentaram apenas a fase Pt (cfc) não havendo deslocamento dos picos desta fase. Nestes materiais os picos referentes a fases de Ru não foram identificados sugerindo que o Ru apresenta-se como uma fase amorfa. Por outro lado, para o material modificado com P, observou-se um deslocamento dos picos da fase Pt(cfc) para ângulos maiores, sugerindo a formação de liga Pt-Ru e também foi observado a presença da fase Ru hexagonal compacta. Os eletrocatalisadores Pt/C e PtRu/C preparados com os suportes contendo heteroátomos apresentaram uma melhora significativa na atividade eletrocatalítica quando comparados aos materiais preparados com o suporte não modificado. A melhora na atividade pode estar relacionada a modificações na interação metal-suporte, bem como, as diferentes espécies Pt e Ru presentes no caso do eletrocatalisador PtRu/C preparado utilizando o suporte modificado com P. / In this work, commercial Vulcan XC72 carbon was modified with heteroatoms like N, S and P by thermal treatment at 800 ° C in the presence of urea, sulfuric acid and phosphoric acid, respectively. The modified carbons were used in the preparation of Pt/C and PtRu/C electrocatalysts and tested for methanol electro-oxidation. The materials were characterized by dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy and cyclic voltammetry. The methanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry. The Raman spectra showed that the intensity ratios of D- and G- bands of the carbon supports modified with heteroatoms were higher than that observed for Vulcan XC72 carbon suggesting the incorporation in the structure. X-ray diffraction analysis showed that Pt/C electrocatalysts have face-centered cubic structure (fcc) and transmission electron micrographs presented particle sizes in the range 4-5 nm. For PtRu/C electrocatalysts made with carbon supports modified with N and S, the X-ray diffraction patterns showed only the presence of Pt(fcc) phase with no shift of the Pt peaks. Peaks of Ru crystalline phases were not identified suggesting that in these materials Ru appears as an amorphous phase. On the other hand, for PtRu/C electrocatalyst prepared with carbon support modified with P, there was a shift of Pt(fcc) peaks to higher angles suggesting Pt-Ru alloy formation and the presence of Ru hexagonal close-packed phase was also observed. Pt/C and PtRu/C electrocatalysts prepared with carbon support modified with heteroatoms showed a significant improvement of electrocatalytic activity when compared to the unmodified material. The improvement in electrocatalytic activity can be related to changes in the metal-support interaction, as well as to the different Pt and Ru species for PtRu/C electrocatalyst prepared with carbon support modified with P.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23719号 / 理博第4809号 / 新制||理||1688(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)准教授 齊藤 尚平, 教授 依光 英樹, 教授 時任 宣博 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

The underlying motivation for the work carried out for this thesis was the growing need for more sustainable technologies. The aim was to synthesize a “palette” of functional nanomaterials using the established technique of hydrothermal carbonization (HTC). The incredible diversity of HTC was demonstrated together with small but steady advances in how HTC can be manipulated to tailor material properties for specific applications. Two main strategies were used to modify the materials obtained by HTC of glucose, a model precursor representing biomass. The first approach was the introduction of heteroatoms, or “doping” of the carbon framework. Sulfur was for the first time introduced as a dopant in hydrothermal carbon. The synthesis of sulfur and sulfur/nitrogen doped microspheres was presented whereby it was shown that the binding state of sulfur could be influenced by varying the type of sulfur source. Pyrolysis may additionally be used to tune the heteroatom binding states which move to more stable motifs with increasing pyrolysis temperature. Importantly, the presence of aromatic binding states in the as synthesized hydrothermal carbon allows for higher heteroatom retention levels after pyrolysis and hence more efficient use of dopant sources. In this regard, HTC may be considered as an “intermediate” step in the formation of conductive heteroatom doped carbon. To assess the novel hydrothermal carbons in terms of their potential for electrochemical applications, materials with defined nano-architectures and high surface areas were synthesized via templated, as well as template-free routes. Sulfur and/or nitrogen doped carbon hollow spheres (CHS) were synthesized using a polystyrene hard templating approach and doped carbon aerogels (CA) were synthesized using either the albumin directed or borax-mediated hydrothermal carbonization of glucose. Electrochemical testing showed that S/N dual doped CHS and aerogels derived via the albumin approach exhibited superior catalytic performance compared to solely nitrogen or sulfur doped counterparts in the oxygen reduction reaction (ORR) relevant to fuel cells. Using the borax mediated aerogel formation, nitrogen content and surface area could be tuned and a carbon aerogel was engineered to maximize electrochemical performance. The obtained sample exhibited drastically improved current densities compared to a platinum catalyst (but lower onset potential), as well as excellent long term stability. In the second approach HTC was carried out at elevated temperatures (550 °C) and pressure (50 bar), corresponding to the superheated vapor regime (htHTC). It was demonstrated that the carbon materials obtained via htHTC are distinct from those obtained via ltHTC and subsequent pyrolysis at 550 °C. No difference in htHTC-derived material properties could be observed between pentoses and hexoses. The material obtained from a polysaccharide exhibited a slightly lower degree of carbonization but was otherwise similar to the monosaccharide derived samples. It was shown that in addition to thermally induced carbonization at 550 °C, the SHV environment exhibits a catalytic effect on the carbonization process. The resulting materials are chemically inert (i.e. they contain a negligible amount of reactive functional groups) and possess low surface area and electronic conductivity which distinguishes them from carbon obtained from pyrolysis. Compared to the materials presented in the previous chapters on chemical modifications of hydrothermal carbon, this makes them ill-suited candidates for electronic applications like lithium ion batteries or electrocatalysts. However, htHTC derived materials could be interesting for applications that require chemical inertness but do not require specific electronic properties. The final section of this thesis therefore revisited the latex hard templating approach to synthesize carbon hollow spheres using htHTC. However, by using htHTC it was possible to carry out template removal in situ because the second heating step at 550 °C was above the polystyrene latex decomposition temperature. Preliminary tests showed that the CHS could be dispersed in an aqueous polystyrene latex without monomer penetrating into the hollow sphere voids. This leaves the stagnant air inside the CHS intact which in turn is promising for their application in heat and sound insulating coatings. Overall the work carried out in this thesis represents a noteworthy development in demonstrating the great potential of sustainable carbon materials. / Das Ziel der vorgelegten Arbeit war es, mit Hilfe der Hydrothermalen Carbonisierung (HTC) eine Palette an verschiedenen Materialien herzustellen, deren physikalische und chemische Eigenschaften auf spezifische Anwendungen zugeschnitten werden können. Die Motivation hierfür stellt die Notwendigkeit, Alternativen zu Materialien zu finden, die auf fossilen Brennstoffen basieren. Dabei stellen vor allem nachhaltige Energien eine der größten Herausforderungen der Zukunft dar. HTC ist ein mildes, nachhaltiges Syntheseverfahren welches prinzipiell die Nutzung von biologischen Rohstoffen (z. B. landwirtschaftlichen Abfallprodukten) für die Herstellung von wertvollen, Kohlenstoff-basierten Materialien erlaubt. Es wurden zwei verschiedene Ansätze verwendet, um hydrothermalen Kohlenstoff zu modifizieren. Zum einen wurde HTC unter „normalen“ Bedingungen ausgeführt, d. h. bei 180 °C und einem Druck von etwa 10 bar. Der Zucker Glukose diente in allen Fällen als Kohlenstoff Vorläufer. Durch Zugabe von stickstoff und /oder schwefelhaltigen Additiven konnte dotierte Hydrothermalkohle hergestellt werden. Dotierte Kohlenstoffe sind bereits für ihre positiven Eigenschaften, wie verbesserte Leitfähigkeit oder erhöhte Stabilität, bekannt. Zusätzlich zu Stickstoff dotierter Hydrothermalkohle, die bereits von anderen Gruppen hergestellt werden konnte, wurde in dieser Arbeit zum ersten Mal Schwefel in Hydrothermalkohle eingebaut. Außerdem wurden verschiedene Ansätze verwendet, um Oberfläche und definierte Morphologie der dotierten Materialien zu erzeugen, welche wichtig für elektrochemische Anwendungen sind. Schwefel- und/oder stickstoffdotierte Kohlenstoff Nanohohlkugeln sowie Kohlenstoff Aerogele konnten hergestellt werden. Mit Hilfe von einem zusätzlichen Pyrolyseschritt (d. h. Erhitzen unter Schutzgas) konnte die Leitfähigkeit der Materialien hergestellt werden, die daraufhin als Nichtmetall-Katalysatoren für Wasserstoff-Brennstoffzellen getestet wurden. Im zweiten Ansatz wurde HTC unter extremen Bedingungen ausgeführt, d. h. bei 550 °C und einem Druck von ca. 50 bar, welches im Wasser Phasendiagram dem Bereich des Heißdampfes entspricht. Es konnte gezeigt werden, dass die so erhaltene Hydrothermalkohle ungewöhnliche Eigenschaften besitzt. So hat die Hochtemperatur-Hydrothermalkohle zwar einen hohen Kohlenstoffgehalt (mehr als 90 Massenprozent), enthält aber auch viele Wasserstoffatome und ist dadurch schlecht leitfähig. Da damit elektrochemische Anwendungen so gut wie ausgeschlossen sind, wurde die Hochtemperatur-Hydrothermalkohle für Anwendungen vorgesehen, welche chemische Stabilität aber keine Leitfähigkeit voraussetzen. So wurden beispielsweise Hochtemperatur-Kohlenstoff-Nanohohlkugeln synthetisiert, die großes Potential als schall- und wärmeisolierende Additive für Beschichtungen darstellen. Insgesamt konnten erfolgreich verschiedenste Materialien mit Hilfe von HTC hergestellt werden. Es ist zu erwarten, dass sie in Zukunft zu nachhaltigen Technologien und damit zu einem weiteren Schritt weg von fossilen Brennstoffen beitragen werden.

The present thesis is to be brought into line with the current need for alternative and sustainable approaches toward energy management and materials design. In this context, carbon in particular has become the material of choice in many fields such as energy conversion and storage. Herein, three main topics are covered: 1)An alternative synthesis strategy toward highly porous functional carbons with tunable porosity using ordinary salts as porogen (denoted as “salt templating”) 2)The one-pot synthesis of porous metal nitride containing functional carbon composites 3)The combination of both approaches, enabling the generation of highly porous composites with finely tunable properties All approaches have in common that they are based on the utilization of ionic liquids, salts which are liquid below 100 °C, as precursors. Just recently, ionic liquids were shown to be versatile precursors for the generation of heteroatom-doped carbons since the liquid state and a negligible vapor pressure are highly advantageous properties. However, in most cases the products do not possess any porosity which is essential for many applications. In the first part, “salt templating”, the utilization of salts as diverse and sustainable porogens, is introduced. Exemplarily shown for ionic liquid derived nitrogen- and nitrogen-boron-co-doped carbons, the control of the porosity and morphology on the nanometer scale by salt templating is presented. The studies within this thesis were conducted with the ionic liquids 1-Butyl-3-methyl-pyridinium dicyanamide (Bmp-dca), 1-Ethyl-3-methyl-imidazolium dicyanamide (Emim-dca) and 1 Ethyl 3-methyl-imidazolium tetracyanoborate (Emim-tcb). The materials are generated through thermal treatment of precursor mixtures containing one of the ionic liquids and a porogen salt. By simple removal of the non-carbonizable template salt with water, functional graphitic carbons with pore sizes ranging from micro- to mesoporous and surface areas up to 2000 m2g-1 are obtained. The carbon morphologies, which presumably originate from different onsets of demixing, mainly depend on the nature of the porogen salt whereas the nature of the ionic liquid plays a minor role. Thus, a structural effect of the porogen salt rather than activation can be assumed. This offers an alternative to conventional activation and templating methods, enabling to avoid multiple-step and energy-consuming synthesis pathways as well as employment of hazardous chemicals for the template removal. The composition of the carbons can be altered via the heat-treatment procedure, thus at lower synthesis temperatures rather polymeric carbonaceous materials with a high degree of functional groups and high surface areas are accessible. First results suggest the suitability of the materials for CO2 utilization. In order to further illustrate the potential of ionic liquids as carbon precursors and to expand the class of carbons which can be obtained, the ionic liquid 1-Ethyl-3-methyl-imidazolium thiocyanate (Emim-scn) is introduced for the generation of nitrogen-sulfur-co-doped carbons in combination with the already studied ionic liquids Bmp-dca and Emim-dca. Here, the salt templating approach should also be applicable eventually further illustrating the potential of salt templating, too. In the second part, a one-pot and template-free synthesis approach toward inherently porous metal nitride nanoparticle containing nitrogen-doped carbon composites is presented. Since ionic liquids also offer outstanding solubility properties, the materials can be generated through the carbonization of homogeneous solutions of an ionic liquid acting as nitrogen as well as carbon source and the respective metal precursor. The metal content and surface area are easily tunable via the initial metal precursor amount. Furthermore, it is also possible to synthesize composites with ternary nitride nanoparticles whose composition is adjustable by the metal ratio in the precursor solution. Finally, both approaches are combined into salt templating of the one-pot composites. This opens the way to the one-step synthesis of composites with tunable composition, particle size as well as precisely controllable porosity and morphology. Thereby, common synthesis strategies where the product composition is often negatively affected by the template removal procedure can be avoided. The composites are further shown to be suitable as electrodes for supercapacitors. Here, different properties such as porosity, metal content and particle size are investigated and discussed with respect to their influence on the energy storage performance. Because a variety of ionic liquids, metal precursors and salts can be combined and a simple closed-loop process including salt recycling is imaginable, the approaches present a promising platform toward sustainable materials design. / Die vorliegende Arbeit basiert auf der Notwendigkeit für eine alternative und nachhaltige Energiewirtschaft sowie alternativer Herstellungsmethoden der damit verbundenen Materialien. Hierbei kommt besonders Kohlenstoffen und kohlenstoffbasierten Systemen eine hohe Bedeutung zu. Im Rahmen der Dissertation wurden drei Ansätze verfolgt, die zu der Entwicklung alternativer Strategien zur Herstellung poröser Heteroatom-enthaltender Kohlenstoffe und deren Komposite beitragen. Die Materialien wurden des Weiteren für die CO2 Nutzung sowie Energiespeicherung in Form von Superkondensatoren getestet. Allen Materialien ist gemeinsam, dass sie ausgehend von ionischen Flüssigkeiten, Salze mit einem Schmelzpunkt unterhalb von 100 °C, als Kohlenstoffvorstufe durch Hochtemperaturverfahren hergestellt wurden. Im ersten Teil wird ein alternatives und nachhaltiges Verfahren zur Herstellung hochporöser Stickstoff und Stickstoff-Bor-haltiger Kohlenstoffe vorgestellt. Bei dieser als „Salztemplatierung“ bezeichneten Methode werden herkömmliche Salze als Porogen verwendet. Damit sind sehr hohe Oberflächen erreichbar, die neben der Porengröße und dem Porenvolumen durch die Variation der Salzspezies und Salzmenge einstellbar sind. Dies bietet gegenüber herkömmlichen Templatierungsverfahren den Vorteil, dass das Salz nach erfolgter Karbonisierung der ionischen Flüssigkeit in Anwesenheit der nicht karbonisierbaren Salzspezies einfach mit Wasser auswaschbar ist. Hierbei ist ein Recyclingprozess denkbar. Bei hohen Synthesetemperaturen werden graphitische, bei niedrigen hochfunktionalisierte, polymerartige Produkte erhalten. Letztere erwiesen sich als vielversprechende Materialien für die CO2 Nutzung. Unter Verwendung einer bisher nicht eingesetzten ionische Flüssigkeit konnte weiterhin die Einführung von Schwefel als Heteroatom ermöglicht werden. Im zweiten Teil wird eine Templat-freie Einschrittsynthese von porösen Kompositen aus Metallnitrid Nanopartikeln und Stickstoff-dotiertem Kohlenstoff vorgestellt. Die Materialien werden ausgehend von einer Lösung aus einer ionischen Flüssigkeit und einem Metallvorläufer hergestellt, wobei die ionische Flüssigkeit sowohl als Kohlenstoffvorläufer als auch als Stickstoffquelle für die Metallnitride dient. Der Metallgehalt, das Metallverhältnis in ternären Nitriden und die Oberfläche sind über den Anteil des Metallvorläufers einstellbar. Schließlich werden beide Ansätze zur Salztemplatierung von den Kompositen kombiniert. Dadurch wird die Einschrittsynthese von Kompositen mit einstellbarer Oberfläche, Zusammensetzung, Partikelgröße und Morphologie ermöglicht. Diese Materialien wurden schließlich als Elektroden für Superkondensatoren getestet und der Einfluss verschiedener Parameter auf die Leistungsfähigkeit untersucht. Aufgrund verschiedener Kombinationsmöglichkeiten von ionischen Flüssigkeiten, Metallvorläufern und Salzen, stellen die hier präsentierten Ansätze eine vielversprechende Plattform für die nachhaltige Materialsynthese dar.

Activated carbons as emerging classes of porous materials have gained tremendous attention because of their versatile applications such as gas storage/separations sorbents, oxygen reduction reaction (ORR) catalysts and supercapacitor electrodes. This diversity originates from fascinating features such as low-cost, lightweight, thermal, chemical and physical stability as well as adjustable textural properties. More interestingly, sole heteroatom or combinations of various elements can be doped into their framework to modify the surface chemistry. Among all dopants, nitrogen as the most frequently used element, induces basicity and charge delocalization into the carbon network and enhances selective adsorption of CO2. Transformation of a task-specific and single source precursor to heteroatom-doped carbon through a one-step activation process is considered a novel and efficient strategy. With these considerations in mind, we developed multiple series of heteroatom doped porous carbons by using nitrogen containing carbon precursors. Benzimidazole-linked polymers (BILP-5), benzimidazole monomer (BI) and azo-linked polymers (ALP-6) were successfully transformed into heteroatom-doped carbons through chemical activation by potassium hydroxide. Alternative activation by zinc chloride and direct heating was also applied to ALP-6. The controlled activation/carbonization process afforded diverse textural properties, adjustable heteroatom doping levels and remarkable gas sorption properties. Nitrogen isotherms at 77 K revealed that micropores dominate the porous structure of carbons. The highest Brunauer-Emett-Teller (BET) surface area (4171 m2 g-1) and pore volume (2.3 cm3 g-1) were obtained for carbon synthesized by KOH activation of BI at 700 °C. In light of the synergistic effect of basic heteroatoms and fine micropores, all carbons exhibit remarkable gas capture and selectivity. Particularly, BI and BIPL-5 derived carbons feature unprecedented CO2 uptakes of 6.2 mmol g-1 (1 bar) and 2.1 mmol g-1 (0.15 bar) at 298 K, respectively. The ALP-6 derived carbons retained considerable amount of nitrogen dopants (up to 14.4 wt%) after heat treatment owing to the presence of more stable nitrogen-nitrogen bonds compared to nitrogen-carbon bonds in BILP-5 and BI precursors. Subsequently, the highest selectivity of 62 for CO2/N2 and 11 for CO2/CH4 were obtained at 298 K for a carbon prepared by KOH activation of ALP-6 at 500 °C.