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Young Investigator Group Nanoscale Solid-Liquid Interfaces

Materials

In our group, we focus primarily on sustainable materials based on inexpensive raw elements, therefore mainly constituted of carbon, nitrogen and early transition metals. Three main class of materials are investigated:

MXenes

Transition metal carbides and nitrides, so-called MXenes, are a new class of layered 2D materials that have shown outstanding properties for a wide range of applications. Especially, they combine a highly conductive carbide (or nitride) core with an electrochemically active functionalized transition metal surface. In addition, their layered structure with hydrophilic surface groups facilitates the confinement of aqueous electrolyte within nanometer scaled interlayer spaces.

We are currently primarily investigating Ti3C2Tx MXene, which is the most stable MXene so far, and are especially interested in understanding the role of its surface chemistry in pseudocapacitive electrochemical energy storage mechanisms. Additionally, we investigate the impact of MXene morphology from delaminated single flakes to few- and multi-layered MXenes particles in thin films on surface chemistry and reactivity of MXene particles. We are also interested in the characterization of the electronic structure of more exotic MXene phases.

(Nano)diamond

Diamond is a wide bandgap semiconductor (5.5 eV), which has exceptional electronic properties, such as a negative electron affinity when its surface is hydrogenated. This property is particularly relevant for photo/electrochemical energy conversion as it allows the emission of highly reactive solvated electrons in liquid environment, which are able to reduce CO2 and N2 molecules directly in their solvated phase. The large bandgap of diamond remains however a drawback for solar-driven applications. One major challenge is therefore to enable the absorption of visible light by diamond and several approaches based on doping, surface functionalization and nanostructuration are currently under investigation. We are investigating how these material properties can:

  • Introduce sub-bandgap electronic states for achieving solar light absorption,

  • Modify the interfacial water hydration structure,

  • Enhance the emission of solvated electrons in water.

We have experience with the characterization of single crystal diamond, polycrystalline and nanostructured diamond films as well as diamond nanoparticles.

Carbon nitride and nitrogen-doped carbon materials

Carbon nitride and nitrogen-doped carbon nanomaterials often exhibit outstanding (photo)electrochemical properties compared to purely carbon-based nanomaterials. For example, polymeric carbon nitride (C3N4) have shown excellent photocatalytic properties for solar fuel production and nitrogen-doped carbon dots are efficient photoabsorber having shown intrinsic electrochemical activity.

We are interested in understanding how nitrogen atoms can:

  • act as electrochemically active sites in a carbon-based matrix,

  • improve charge transfer processes at the solid-liquid interface,

  • alter the interfacial water organization.