2D materials

The study of 2D materials has been present along my whole academic trajectory. Here are some examples:

I started with the study of the effect of parent graphite on the structure of graphene oxide (GO) layers during my master thesis.

Then I succeeded in the first isolation of antimonene, a single layer of antimony atoms, leading the experimental research on this novel 2D material. We demonstrated that it was possible to obtain it by mechanical and liquid phase exfoliation and studied some of its fundamental properties.

I carried out studies on graphene, locally tuning its properties at ultrahigh pressures with a diamond AFM tip. Using this approach, we p-doped specific regions that exhibited a much lower electrical contact resistance. We also used this methodology to improve the adhesion of graphene to the substrate, better sealing graphene blisters and reducing gas leakage from them.

I have also made contributions towards the understanding of the fundamental properties of hexagonal boron nitride (hBN). I successfully gave the first experimental evidence of piezoelectricity in monolayer hBN and participated in the first experimental evidence that the presence of out-of-plane dipoles in marginally twisted hBN crystals generate moiré superlattices of spontaneously charge-polarized domains, effectively creating ferroelectric-like bilayer domains at the interface.

Using 2D materials to fabricate thickness-controlled nanochannels with atomic precision, I took part in the first reliable measurement of the dielectric constant of interfacial water, finding that its out-of-plane dielectric constant presents an anomalously low value, ~2.

I have studied fundamental mechanical properties of two-dimensional materials, in particular, how the van der Waals (vdW) interaction affects wrinkle formation in 2D materials, analyzing the formation of wrinkles around mono- and few-layer “bubbles” in both incommensurate and commensurate vdW heterostructures.

 1D materials

The study of 1D materials has been also present along my whole trajectory. Here are some examples:

Estimation of the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes with AFM.

I was able to visualize the helix periodicity of dsRNA equilibrated on mica under liquid using different AFM high-sensitive force-detection methods.

I succeeded in the study of the dependence of the electrical resistance with the length of bundles of few down to just one/two MMX chains (MMX metal-organic polymers are sequences of halide (X) atoms that bind subunits with two metal ions (MM) connected by organic ligands). Our experiemal measurements in [Pt2(EtCS2)4I]n chains, complemented with theoretical simulations including structural defects, confirmed that the current is limited by the defects, in this case mainly by vacant iodine atoms, through which the current is limited to flow. Even so, the electrical transport measured over distances above 250 nm exceeded that of all other molecular wires reported so far.