{"id":{"repo_id":"tu-berlin","oai_identifier":"oai:depositonce.tu-berlin.de:11303/26038"},"canonical_url":"https://search.dev.ndltd.org/etd/tu-berlin/oai:depositonce.tu-berlin.de:11303/26038","repository":{"repo_id":"tu-berlin","name":"Technische Universität Berlin","base_url":"https://api-depositonce.tu-berlin.de/server/oai/request"},"display":{"title":"Nanoscale imaging of MXenes by X-ray microscopy","abstract":"The global transition towards a carbon-neutral society by 2050 necessitates not only the development of renewable energy sources but also advanced energy storage technologies to address the intermittent nature of solar, wind, and other sustainable energy systems. In this context, MXenes, a novel class of two-dimensional (2D) materials, have attracted considerable interest for their promising applications in energy storage. MXenes, with their unique structure and chemical diversity, offer a combination of metallic conductivity and tunable surface properties, making them ideal candidates for energy storage devices like batteries and supercapacitors. Despite their potential, fundamental questions remain regarding the intercalation and redox mechanisms of individual MXene flakes, the coverage of MXenes with surface terminations, and defects that influence their electrochemical performance. This thesis explores the chemical and structural properties of Ti3C2Tx, Mo2CTx, and vacancy-ordered Mo1.33CTx MXenes, focusing on their thermal stability, surface chemistry, and interaction with aqueous electrolytes. Scanning X-ray Microscopy (SXM) is a suitable technique for the investigation of the surface and core chemistry of MXenes, particularly for capturing post mortem the intercalation mechanisms of a Li-ion battery and during exposure to varying conditions (temperature, gas, and liquid). SXM provided critical insights into the local distribution and chemical nature of surface terminations, defects, and intercalated water molecules, as well as the redox behavior of MXene flakes at the nanoscale. The thesis reveals that intercalants and surface terminations such as O, OH, and F play a significant role in the thermal stability and redox reactions of MXenes, with O-terminated surfaces being active sites for redox reactions. These findings also highlight the effect of ordered vacancies and surface chemistry in Mo-based MXenes on their stability. These MXenes present signs of degradation during annealing above 400 °C, unlike the thermally stable Ti3C2Tx MXene. Additionally, the surface oxidation of Ti3C2Tx MXene flakes, induced by their exposure to alkaline electrolyte, is only partially reversible by exposure to acidic electrolyte. These findings enhance the understanding of MXenes in energy storage, revealing at the nanoscale the interplay of intercalation and surface chemistry. Monitoring surface chemistry down to the level of single MXene flake provides valuable insights into the chemical changes that can occur during oxygenation or ion intercalation, adding to the understanding of electrochemical energy storage mechanisms in MXenes.","abstract_html":"The global transition towards a carbon-neutral society by 2050 necessitates not only the development of renewable energy sources but also advanced energy storage technologies to address the intermittent nature of solar, wind, and other sustainable energy systems. In this context, MXenes, a novel class of two-dimensional (2D) materials, have attracted considerable interest for their promising applications in energy storage. MXenes, with their unique structure and chemical diversity, offer a combination of metallic conductivity and tunable surface properties, making them ideal candidates for energy storage devices like batteries and supercapacitors. Despite their potential, fundamental questions remain regarding the intercalation and redox mechanisms of individual MXene flakes, the coverage of MXenes with surface terminations, and defects that influence their electrochemical performance. This thesis explores the chemical and structural properties of Ti3C2Tx, Mo2CTx, and vacancy-ordered Mo1.33CTx MXenes, focusing on their thermal stability, surface chemistry, and interaction with aqueous electrolytes. Scanning X-ray Microscopy (SXM) is a suitable technique for the investigation of the surface and core chemistry of MXenes, particularly for capturing post mortem the intercalation mechanisms of a Li-ion battery and during exposure to varying conditions (temperature, gas, and liquid). SXM provided critical insights into the local distribution and chemical nature of surface terminations, defects, and intercalated water molecules, as well as the redox behavior of MXene flakes at the nanoscale. The thesis reveals that intercalants and surface terminations such as O, OH, and F play a significant role in the thermal stability and redox reactions of MXenes, with O-terminated surfaces being active sites for redox reactions. These findings also highlight the effect of ordered vacancies and surface chemistry in Mo-based MXenes on their stability. These MXenes present signs of degradation during annealing above 400 °C, unlike the thermally stable Ti3C2Tx MXene. Additionally, the surface oxidation of Ti3C2Tx MXene flakes, induced by their exposure to alkaline electrolyte, is only partially reversible by exposure to acidic electrolyte. These findings enhance the understanding of MXenes in energy storage, revealing at the nanoscale the interplay of intercalation and surface chemistry. Monitoring surface chemistry down to the level of single MXene flake provides valuable insights into the chemical changes that can occur during oxygenation or ion intercalation, adding to the understanding of electrochemical energy storage mechanisms in MXenes.","abstract_has_math":false,"creators":["Amargianou, Faidra"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Petit, Tristan"],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026","date_published":"2026","updated_at":"2026-07-27T21:28:29Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":["https://creativecommons.org/licenses/by/4.0/"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://doi.org/10.14279/depositonce-24866"],"render_values":[{"text":"https://doi.org/10.14279/depositonce-24866","href":"https://doi.org/10.14279/depositonce-24866","code":true}]}]},"links":{"outbound_url":"https://depositonce.tu-berlin.de/handle/11303/26038","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Petit, Tristan"]},{"key":"dc:creator","label":"Author","values":["Amargianou, Faidra"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-03-02T09:40:56Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-03-02T09:40:56Z"]},{"key":"dc:date.issued","label":"Date","values":["2026"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights.uri","label":"Rights URI","values":["https://creativecommons.org/licenses/by/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://depositonce.tu-berlin.de/handle/11303/26038","https://doi.org/10.14279/depositonce-24866"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The global transition towards a carbon-neutral society by 2050 necessitates not only the development of renewable energy sources but also advanced energy storage technologies to address the intermittent nature of solar, wind, and other sustainable energy systems. In this context, MXenes, a novel class of two-dimensional (2D) materials, have attracted considerable interest for their promising applications in energy storage. MXenes, with their unique structure and chemical diversity, offer a combination of metallic conductivity and tunable surface properties, making them ideal candidates for energy storage devices like batteries and supercapacitors. Despite their potential, fundamental questions remain regarding the intercalation and redox mechanisms of individual MXene flakes, the coverage of MXenes with surface terminations, and defects that influence their electrochemical performance. This thesis explores the chemical and structural properties of Ti3C2Tx, Mo2CTx, and vacancy-ordered Mo1.33CTx MXenes, focusing on their thermal stability, surface chemistry, and interaction with aqueous electrolytes. Scanning X-ray Microscopy (SXM) is a suitable technique for the investigation of the surface and core chemistry of MXenes, particularly for capturing post mortem the intercalation mechanisms of a Li-ion battery and during exposure to varying conditions (temperature, gas, and liquid). SXM provided critical insights into the local distribution and chemical nature of surface terminations, defects, and intercalated water molecules, as well as the redox behavior of MXene flakes at the nanoscale. The thesis reveals that intercalants and surface terminations such as O, OH, and F play a significant role in the thermal stability and redox reactions of MXenes, with O-terminated surfaces being active sites for redox reactions. These findings also highlight the effect of ordered vacancies and surface chemistry in Mo-based MXenes on their stability. These MXenes present signs of degradation during annealing above 400 °C, unlike the thermally stable Ti3C2Tx MXene. Additionally, the surface oxidation of Ti3C2Tx MXene flakes, induced by their exposure to alkaline electrolyte, is only partially reversible by exposure to acidic electrolyte. These findings enhance the understanding of MXenes in energy storage, revealing at the nanoscale the interplay of intercalation and surface chemistry. Monitoring surface chemistry down to the level of single MXene flake provides valuable insights into the chemical changes that can occur during oxygenation or ion intercalation, adding to the understanding of electrochemical energy storage mechanisms in MXenes.","Die weltweite Initiative hin zu einer kohlenstoffneutralen Gesellschaft bis 2050 erfordert nicht nur die Entwicklung erneuerbarer Energiequellen, sondern auch fortschrittliche Energiespeichertechnologien, um die schwankende Natur von Solar-, Wind- und anderen nachhaltigen Energiesystemen zu bewältigen. In diesem Zusammenhang haben MXene, eine neuartige Klasse zweidimensionaler (2D) Materialien, aufgrund ihrer vielversprechenden Anwendungen im Bereich der Energiespeicher großes Interesse geweckt. MXene bieten durch ihre einzigartige Struktur und chemische Vielfalt eine Kombination aus metallischer Leitfähigkeit und abstimmbaren Oberflächeneigenschaften, was sie zu idealen Kandidaten für Energiespeicher wie Batterien und Superkondensatoren macht. Trotz ihres Potentials bleiben bislang grundlegende Fragen zu den Interkalations- und Redoxmechanismen einzelner MXene-Flocken, den Oberflächenterminierungen und zu Defekten, die ihre elektrochemische Leistung beeinflussen, offen. Diese Dissertation beleuchtet die chemischen und strukturellen Eigenschaften von Ti3C2Tx , Mo2CTx und Leerstellen-geordneten Mo1.33CTx MXenen, mit Fokus auf ihrer thermischen Stabilität, Oberflächenchemie und Interaktion mit wässrigen Elektrolyten. Die nanoskalige Chemie der Oberfläche und des Kernes wurde sowohl ex situ als auch in situ mittels Raster-Röntgenmikroskopie (Scanning X-Ray Microscopy, SXM) untersucht, insbesondere um die Interkalationsmechanismen in einer Li-Ionen-Batterie mit MXene als Elektrodenmaterial post mortem und während der Exposition gegenüber unterschiedlichen Bedingungen (Temperatur, Gas und Flüssigkeit) zu erfassen. SXM lieferte entscheidende Einblicke in die lokale Verteilung und chemische Natur von Oberflächenterminierungen, Defekten und interkalierten Wassermolekülen sowie in das Redoxverhalten von MXene- Flocken auf der Nanoskala. Diese Dissertation zeigt, dass Interkalanten und Oberflächenterminierungen wie O, OH und F eine bedeutende Rolle für die thermische Stabilität und Redoxreaktionen von MXenen spielen, wobei O-terminierte Oberflächen als aktive Stellen für Redoxreaktionen fungieren. Diese Erkenntnisse unterstreichen auch den Einfluss geordneter Defekte und der Oberflächenchemie bei Mo-basierten MXenen auf ihre Stabilität. Diese MXene zeigen Anzeichen von Degradation während des Ausheizens bei Temperaturen über 400 °C, im Gegensatz zu dem thermisch stabilen Ti3C2Tx MXene. Darüber hinaus ist die Oxidation der Oberfläche der Ti3C2Tx MXene-Flocken, verursacht durch ihren Kontakt mit alkalinem Elektrolyt, teilweise reversibel durch Kontakt mit saurem Elektrolyten. Diese Ergebnisse erweitern das Verständnis von MXenen in der Energiespeicherung, indem sie das Zusammenspiel von Interkalation und Oberflächenchemie auf der Nanoskala offenbaren. Die Überwachung der Oberflächenchemie bis hinunter zur Ebene einzelner MXene-Flocken liefert wertvolle Einblicke in lokale chemische Veränderungen, die während der Oxidation oder Ioneninterkalation auftreten, und trägt so zum Verständnis der elektrochemischen Energiespeichermechanismen in MXenes bei."]},{"key":"dc:title","label":"Title","values":["Nanoscale imaging of MXenes by X-ray microscopy"]}]}],"canonical_facts":{"dc:contributor.advisor":["Petit, Tristan"],"dc:creator":["Amargianou, Faidra"],"dc:date.accessioned":["2026-03-02T09:40:56Z"],"dc:date.available":["2026-03-02T09:40:56Z"],"dc:date.issued":["2026"],"dc:description.abstract":["The global transition towards a carbon-neutral society by 2050 necessitates not only the development of renewable energy sources but also advanced energy storage technologies to address the intermittent nature of solar, wind, and other sustainable energy systems. In this context, MXenes, a novel class of two-dimensional (2D) materials, have attracted considerable interest for their promising applications in energy storage. MXenes, with their unique structure and chemical diversity, offer a combination of metallic conductivity and tunable surface properties, making them ideal candidates for energy storage devices like batteries and supercapacitors. Despite their potential, fundamental questions remain regarding the intercalation and redox mechanisms of individual MXene flakes, the coverage of MXenes with surface terminations, and defects that influence their electrochemical performance. This thesis explores the chemical and structural properties of Ti3C2Tx, Mo2CTx, and vacancy-ordered Mo1.33CTx MXenes, focusing on their thermal stability, surface chemistry, and interaction with aqueous electrolytes. Scanning X-ray Microscopy (SXM) is a suitable technique for the investigation of the surface and core chemistry of MXenes, particularly for capturing post mortem the intercalation mechanisms of a Li-ion battery and during exposure to varying conditions (temperature, gas, and liquid). SXM provided critical insights into the local distribution and chemical nature of surface terminations, defects, and intercalated water molecules, as well as the redox behavior of MXene flakes at the nanoscale. The thesis reveals that intercalants and surface terminations such as O, OH, and F play a significant role in the thermal stability and redox reactions of MXenes, with O-terminated surfaces being active sites for redox reactions. These findings also highlight the effect of ordered vacancies and surface chemistry in Mo-based MXenes on their stability. These MXenes present signs of degradation during annealing above 400 °C, unlike the thermally stable Ti3C2Tx MXene. Additionally, the surface oxidation of Ti3C2Tx MXene flakes, induced by their exposure to alkaline electrolyte, is only partially reversible by exposure to acidic electrolyte. These findings enhance the understanding of MXenes in energy storage, revealing at the nanoscale the interplay of intercalation and surface chemistry. Monitoring surface chemistry down to the level of single MXene flake provides valuable insights into the chemical changes that can occur during oxygenation or ion intercalation, adding to the understanding of electrochemical energy storage mechanisms in MXenes.","Die weltweite Initiative hin zu einer kohlenstoffneutralen Gesellschaft bis 2050 erfordert nicht nur die Entwicklung erneuerbarer Energiequellen, sondern auch fortschrittliche Energiespeichertechnologien, um die schwankende Natur von Solar-, Wind- und anderen nachhaltigen Energiesystemen zu bewältigen. In diesem Zusammenhang haben MXene, eine neuartige Klasse zweidimensionaler (2D) Materialien, aufgrund ihrer vielversprechenden Anwendungen im Bereich der Energiespeicher großes Interesse geweckt. MXene bieten durch ihre einzigartige Struktur und chemische Vielfalt eine Kombination aus metallischer Leitfähigkeit und abstimmbaren Oberflächeneigenschaften, was sie zu idealen Kandidaten für Energiespeicher wie Batterien und Superkondensatoren macht. Trotz ihres Potentials bleiben bislang grundlegende Fragen zu den Interkalations- und Redoxmechanismen einzelner MXene-Flocken, den Oberflächenterminierungen und zu Defekten, die ihre elektrochemische Leistung beeinflussen, offen. Diese Dissertation beleuchtet die chemischen und strukturellen Eigenschaften von Ti3C2Tx , Mo2CTx und Leerstellen-geordneten Mo1.33CTx MXenen, mit Fokus auf ihrer thermischen Stabilität, Oberflächenchemie und Interaktion mit wässrigen Elektrolyten. Die nanoskalige Chemie der Oberfläche und des Kernes wurde sowohl ex situ als auch in situ mittels Raster-Röntgenmikroskopie (Scanning X-Ray Microscopy, SXM) untersucht, insbesondere um die Interkalationsmechanismen in einer Li-Ionen-Batterie mit MXene als Elektrodenmaterial post mortem und während der Exposition gegenüber unterschiedlichen Bedingungen (Temperatur, Gas und Flüssigkeit) zu erfassen. SXM lieferte entscheidende Einblicke in die lokale Verteilung und chemische Natur von Oberflächenterminierungen, Defekten und interkalierten Wassermolekülen sowie in das Redoxverhalten von MXene- Flocken auf der Nanoskala. Diese Dissertation zeigt, dass Interkalanten und Oberflächenterminierungen wie O, OH und F eine bedeutende Rolle für die thermische Stabilität und Redoxreaktionen von MXenen spielen, wobei O-terminierte Oberflächen als aktive Stellen für Redoxreaktionen fungieren. Diese Erkenntnisse unterstreichen auch den Einfluss geordneter Defekte und der Oberflächenchemie bei Mo-basierten MXenen auf ihre Stabilität. Diese MXene zeigen Anzeichen von Degradation während des Ausheizens bei Temperaturen über 400 °C, im Gegensatz zu dem thermisch stabilen Ti3C2Tx MXene. Darüber hinaus ist die Oxidation der Oberfläche der Ti3C2Tx MXene-Flocken, verursacht durch ihren Kontakt mit alkalinem Elektrolyt, teilweise reversibel durch Kontakt mit saurem Elektrolyten. Diese Ergebnisse erweitern das Verständnis von MXenen in der Energiespeicherung, indem sie das Zusammenspiel von Interkalation und Oberflächenchemie auf der Nanoskala offenbaren. Die Überwachung der Oberflächenchemie bis hinunter zur Ebene einzelner MXene-Flocken liefert wertvolle Einblicke in lokale chemische Veränderungen, die während der Oxidation oder Ioneninterkalation auftreten, und trägt so zum Verständnis der elektrochemischen Energiespeichermechanismen in MXenes bei."],"dc:identifier.uri":["https://depositonce.tu-berlin.de/handle/11303/26038","https://doi.org/10.14279/depositonce-24866"],"dc:language.iso":["en"],"dc:rights.uri":["https://creativecommons.org/licenses/by/4.0/"],"dc:title":["Nanoscale imaging of MXenes by X-ray microscopy"],"dc:type":["Doctoral Thesis"]},"updated_at":"2026-07-27T21:28:29Z"}