Nanoengineering of multicomponent reversible graphene superlattices: Probing the fundamentals from the molecular level to the device scale.

Projektinformationen

MRGS-Nano-Spec.

ID Finanzhilfevereinbarung: 101105762

DOI

10.3030/101105762

Projekt abgeschlossen

EK-Unterschriftsdatum 7 April 2023

Startdatum 1 August 2023

Enddatum 31 Juli 2025

Finanziert unter

• Marie Skłodowska-Curie Actions (MSCA)

Gesamtkosten

Keine Daten

EU-Beitrag

€ 191 760,00

Koordiniert durch

KATHOLIEKE UNIVERSITEIT LEUVEN
Belgium

Periodic Reporting for period 1 - MRGS-Nano-Spec. (Nanoengineering of multicomponent reversible graphene superlattices: Probing the fundamentals from the molecular level to the device scale.)

Berichtszeitraum: 2023-08-01 bis 2025-07-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

This project set out to explore the nanoengineering of single-layer graphene, an atomically thin sheet of carbon atoms arranged in a honeycomb structure, with the goal of fabricating novel graphene-based hybrid materials with advanced functionalities. Although graphene displays exceptional chemical, physical, mechanical, and electrical properties, its intrinsic characteristics often limit its direct use in many technological applications and hinder the development of next-generation devices in fields such as optoelectronics, sensing, and energy harvesting.
A promising way to overcome these limitations is through chemical functionalization, where carefully selected functional groups are covalently anchored to graphene, or by controlling the molecular orientation and self-assembly of physisorbed molecules at its surface. Both approaches offer the possibility of tailoring graphene’s properties in a highly controlled manner, creating customized materials with novel behaviors.
The ambition of this project was to uncover the fundamental physical and chemical mechanisms governing multicomponent graphene functionalization and to use this knowledge to build a novel photo-switchable hybrid graphene superlattice. In parallel, the project aimed to advance nanoscale surface characterization of atomically thin graphene, enabling the visualization and understanding of defect distribution at the molecular level, a critical step toward precisely engineering new functionalities.
The overall objectives were therefore to:
• Develop facile and efficient covalent functionalization strategies to pattern graphene with high spatial resolution.
• Explore and fabricate light-controlled photochromic molecules as building blocks for photo-switchable graphene superlattices.
• Establish nanoscale optical and structural characterization protocols to upscale the fundamental knowledge of hybrid graphene structures.
Through these objectives, the project directly addresses the demand for cost-effective, sustainable, and multifunctional materials. It also demonstrates the fabrication of novel hybrid graphene substrates, laying the foundation for future applications in optoelectronics, sensing, and nanotechnology.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

To achieve the project’s objectives, a combination of surface chemistry, optical spectroscopy, and advanced microscopy techniques was employed. Two complementary methods were developed to covalently pattern graphene: light-mediated (photochemical) and wet-chemical functionalization. These approaches enabled the fabrication of a variety of customized graphene architectures, including top-side, bottom-side, Janus-type, and multicomponent patterns.
The functionalized materials were comprehensively characterized using state-of-the-art tools such as Raman spectroscopy and imaging, electron microscopy, and scanning probe techniques (AFM, KPFM). While nanospectroscopy methods such as Tip-Enhanced Raman Spectroscopy (TERS) and nano-IR did not yield the expected results for single-layer graphene, complementary Electron Diffraction (ED) and Electron Energy Loss Spectroscopy (EELS) successfully provided nanoscale structural and chemical information. Importantly, the kinetics of molecule desorption (degrafting) were investigated through a correlative approach that combined time-resolved Raman spectroscopy, ED, and EELS. This demonstrated, for the first time, the complete restoration of pristine graphene with nanoscale spatial resolution.
To advance the development of photo-switchable graphene superlattices, spiropyran derivatives were employed and their reversible photoisomerization under ultraviolet (UV) light was established. Although the switching behavior was confirmed by distinct color changes, high-resolution Scanning Tunneling Microscopy (STM) images of self-assembled networks could not be obtained, limiting direct experimental evidence of superlattice formation.
As a strategic alternative, the project successfully demonstrated the fabrication of novel covalently linked graphene–perovskite heterostructure. Detailed optical and structural studies revealed distinct behaviors between covalent and van der Waals (vdW) regions, providing new insights into hybrid material design and opening promising directions for future optoelectronic applications.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The project delivered several results that advance the state of the art in graphene research and hybrid material design.
A straightforward and efficient photopatterning methodology was established under both liquid and dry conditions, enabling spatially controlled covalent patterning of graphene with high precision. This approach allowed the selective anchoring of different functional groups at desired locations, making it possible to achieve different patterned substrates. These advanced graphene architectures were thoroughly characterized using a suite of state-of-the-art techniques to evaluate their efficiency and surface properties. The nanoscale chemical and structural visualization of the functionalized graphene has also yields the comprehensive information into its surface properties.
A major breakthrough was the demonstration of reversible covalent functionalization, where covalently bound molecules could be selectively removed with the aid of a focused laser, restoring its pristine characteristics without introducing additional defects. Using a correlative approach that combined time-resolved Raman spectroscopy, Electron Diffraction (ED), and Electron Energy Loss Spectroscopy (EELS), the real-time insight into the degrafting process was elucidaded for the first time. This revealed the back-conversion kinetics from sp³ to sp² hybridization and established the foundation for re-usable and sustainable graphene platforms.
Another significant achievement was the first prototype demonstration of a covalently linked graphene–perovskite conjugate system. Detailed optical and structural characterization, including Raman mapping, photoluminescence (PL) spectroscopy, SEM, and synchrotron-based XANES and EXAFS measurements, revealed clear domain-dependent behaviors between van der Waals and covalently bonded interfaces. These findings open new research directions for hybrid materials with tailored optoelectronic properties. However, further research, dedicated technology development, and potential industrial collaborations will be required to advance this type of conjugate system toward practical applications.
Together, these results not only advance the fundamental knowledge of graphene functionalization, restoration, and hybrid materials, but also establish practical methodologies that can support future applications in optoelectronics, sensing, and nanomaterials. At the same time, they provide a solid foundation for developing sustainable and re-usable graphene-based technologies.

Light-mediated covalent patterning of graphene and multimodal surface characterization