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Papers by Liubov Belyaeva

Graphene at fluidic interfaces

In this thesis unconventional tools based on fluidic interfaces were developed to study the surfa... more In this thesis unconventional tools based on fluidic interfaces were developed to study the surface and interfacial chemistry of graphene, to characterize the intrinsic properties of graphene, to disentangle the effects of substrate and of the environmental factors, and to improve handling protocols towards the preservation of the graphene cleanliness, morphology and electrical properties.The use of liquid interfaces in graphene research is now emerging, and this thesis shows that the structural adaptability, molecular smoothness and weaker (compared to solids) intermolecular bonding of fluidic interfaces allow for experimental designs radically different from those involving solid substrates. By demonstrating that fluidic interfaces preserve graphene clean, smooth, unstrained and undoped, and by exploiting these advantages, a step forward was made to the design of (more) accessible and efficient graphene-based devices and technologies.Supramolecular & Biomaterials Chemistr

Langmuir, 2020

Theoretical simulations have predicted that a lipid bilayer forms a stable superstructure when a ... more Theoretical simulations have predicted that a lipid bilayer forms a stable superstructure when a sheet of graphene is inserted in its hydrophobic core. We experimentally produced for the first time a lipid−graphene−lipid assembly by combining the Langmuir− Blodgett and the Langmuir−Schaefer methods. Graphene is sandwiched and remains flat within the hydrophobic core of the lipid bilayer. Using infrared spectroscopy, ellipsometry, and neutron reflectometry, we characterized the superstructure at every fabrication step. The hybrid superstructure is mechanically stable and graphene does not disturb the natural lipid bilayer structure.

DSC for the Study of NANO- materials and mesoporouse bulk materials

New analytical tool to monitor the dispersity of detonation nanodiamonds

Langmuir, 2021

Interactions between water and graphene can be probed on a macroscopic level through wettability ... more Interactions between water and graphene can be probed on a macroscopic level through wettability by measuring the water contact angle and on a microscopic level through water desorption kinetic studies using surface science methods. The contact angle studies of graphene pinpointed the critical role of sample preparation and measurement conditions in assessing the wettability of graphene. So far, studies of water desorption from graphene under the conditions of ultrahigh vacuum provided superior control over the environment but disregarded the importance of sample preparation. Here, we systematically examined the effect of the morphology of the growth substrate and of the transfer process on the macroscopic and microscopic wettability of graphene. Remarkably, the macroscopic wetting transparency of graphene does not always translate into microscopic wetting transparency, particularly in the case of an atomically defined Cu(111) substrate. Additionally, subtle differences in the type of substrates significantly alter the interactions between graphene and the first monolayer of adsorbed water but have a negligible effect on the apparent macroscopic wettability. This work looks into the correlations between the wetting properties of graphene, both on the macroscopic and microscopic scales, and highlights the importance of sample preparation in understanding the surface chemistry of graphene.

Science China Chemistry, 2021

Graphene as a two-dimensional material is prone to hydrocarbon contaminations, which can signific... more Graphene as a two-dimensional material is prone to hydrocarbon contaminations, which can significantly alter its intrinsic electrical properties. Herein, we implement a facile hydrogenation-dehydrogenation strategy to remove hydrocarbon contaminations and preserve the excellent transport properties of monolayer graphene. Using electron microscopy we quantitatively characterized the improved cleanness of hydrogenated graphene compared to untreated samples. In situ spectroscopic investigations revealed that the hydrogenation treatment promoted the adsorption ofytyt water at the graphene surface, resulting in a protective layer against the re-deposition of hydrocarbon molecules. Additionally, the further dehydrogenation of hydrogenated graphene rendered a more pristine-like basal plane with improved carrier mobility compared to untreated pristine graphene. Our findings provide a practical post-growth cleaning protocol for graphene with maintained surface cleanness and lattice integrity...

Nature communications, Jan 10, 2018

Square millimeters of free-standing graphene do not exist per se because of thermal fluctuations ... more Square millimeters of free-standing graphene do not exist per se because of thermal fluctuations in two-dimensional crystals and their tendency to collapse during the detachment from the substrate. Here we form millimeter-scale freely suspended graphene by injecting an air bubble underneath a graphene monolayer floating at the water-air interface, which allowed us to measure the contact angle on fully free-standing non-contaminated graphene. A captive bubble measurement shows that free-standing clean graphene is hydrophilic with a contact angle of 42° ± 3°. The proposed design provides a simple tool to probe and explore the wettability of two-dimensional materials in free-standing geometries and will expand our perception of two-dimensional materials technologies from microscopic to now millimeter scales.

Chemical Society reviews, Jan 27, 2015

Graphene and other two dimensional (2D) materials are currently integrated into nanoscaled device... more Graphene and other two dimensional (2D) materials are currently integrated into nanoscaled devices that may - one day - sequence genomes. The challenge to solve is conceptually straightforward: cut a sheet out of a 2D material and use the edge of the sheet to scan an unfolded biomolecule from head to tail. As the scan proceeds - and because 2D materials are atomically thin - the information provided by the edge might be used to identify different segments - ideally single nucleotides - in the biomolecular strand. So far, the most efficient approach was to drill a nano-sized pore in the sheet and use this pore as a channel to guide and detect individual molecules by measuring the electrochemical ionic current. Nanoscaled gaps between two electrodes in 2D materials recently emerged as powerful alternatives to nanopores. This article reviews the current status and prospects of integrating 2D materials in nanopores, nanogaps and similar devices for single molecule biosensing application...

The Journal of Physical Chemistry C, 2013

Graphite oxide is selectively intercalated by methanol when exposed to liquid water/methanol mixt... more Graphite oxide is selectively intercalated by methanol when exposed to liquid water/methanol mixtures with methanol fraction in the range 20−100%. Insertion of water into the GO structure occurs only when the content of water in the mixture with methanol is increased up to 90%. This conclusion is confirmed by both ambient temperature XRD data and specific temperature variations of the GO structure due to insertion/deinsertion of an additional methanol monolayer observed upon cooling/heating. The composition of GO−methanol solvate phases was determined for both low temperature and ambient temperature phases. Understanding of graphite oxide structural properties in binary water/methanol mixtures is important for understanding the unusual permeation properties of graphene oxide membranes for water and alcohols. It is suggested that graphite oxide prepared by Brodie's method can be used for purification of water using selective extraction of methanol from water/alcohol mixtures.

Advanced materials (Deerfield Beach, Fla.), 2018

Establishing contact angles on graphene-on-water has been a long-standing challenge as droplet de... more Establishing contact angles on graphene-on-water has been a long-standing challenge as droplet deposition causes free-floating graphene to rupture. The current work presents ice and hydrogels as substrates mimicking water while offering a stable support for graphene. The lowest water contact angles on graphene ever measured, namely on graphene-on-ice and graphene-on-hydrogel, are recorded. The contact angle measurements of liquids with a range of polarities allow the transparency of graphene toward polar and dispersive interactions to be quantified demonstrating that graphene in water is hydrophilic. These findings are anticipated to shed light on the inconsistencies reported so far on the wetting properties of graphene, and most particularly on their implications toward rationalizing how molecules interact with graphene in water.