Carbon nanotube are exceptional mechanical resonators. Indeed, they are extremely light, with masses in the range of ~ag (1 ag = 10-18g). In addition, as bottom-up materials, they do not suffer from surface defect as their top-down counterparts (MEMS etched from silicon or nitride substrates). From these 2 features stems their exquisite mass sensitivity as demonstrated by Chaste et al[1] with a sensitivity of 1.4 yg in a cryogenic environment. Yet, this sensitivity was reported to be much worse at room temperature, about 25 zg[2]. This has hindered the use of CNTs as sensors in real-life applications. In this work, we propose a unique set-up to track in real time the vibrations of a individual single-walled CNT (SWCNTs) at room temperature. It allows us to demonstrate a record mass sensitivity of 0.2 yg +/- 0.17 yg (1 yg = 10-24 g, the mass of a single proton).We carefully investigated the noise mechanisms that could be limiting the sensitivity: set-up noise, interaction with the gas phase and Brownian motion to name only the most important ones. We found that our device operates closely to the Brownian noise limit and is not limited by external sources of noise. Surprisingly, increasing the pressure up to 35 mbar (after which we could not detect the motion due to viscous damping) does not seem to degrade the sensitivity, which might be preserved up to ambient pressure. Finally, yet importantly, the exquisite sensitivity observed here is similar for several devices, making it a reliable and reproducible feature. This opens up the possibility to perform single-molecule sensing, in various contexts such as biological applications, mass spectrometry or surface science[1,3].[1] J. Chaste, A. Eichler, J. Moser, G. Ceballos, R. Rurali, A. Bachtold (2012). A nanomechanical mass sensor with yoctogram resolution, Nat. Nano, 7, 5, 301-304.[2] B. Lassagne, D. Garcia-Sanchez, A. Aguasca, A. Bachtold (2008). Ultrasensitive mass sensing with a nanotube electromechanical resonator, Nano. Let., 8, 11, 3735 – 3738.[3] P. Robin, L. Bocquet (2023). Nanofluidics at the crossroads, Soft Cond. Matt., preprint.

This article shows the differentiation between water adsorbed outside of a single-walled carbon nanotube (CNT) and that confined inside. This distinction is made possible by tracking the electronic transport of a CNT-based field effect transistor constructed with an individual nanotube and exposed to controlled environments. The presence of water shifts the electrical neutrality point, indicating charge transfer between the nanotube and its environment. We identify three types of water molecules: (i) chemically adsorbed on the SiO2 surface, forming silanol groups, (ii) physically adsorbed outside the nanotube, and (iii) confined inside. The first type is eliminated only by high-temperature treatment under vacuum, while the latter two desorb at room temperature under moderate or high vacuum, i.e. 10−3 mbar. We observe that water confinement inside the nanotube is fast and thermodynamically favorable, with no qualitative influence from the metallicity of the nanotube.

Carbon nanotubes as nanomechanical resonators are very promising systems due to their small size and mass as well as their stiffness that grant them great sensitivity as a sensor. As a result, ample research [1][2] is oriented towards these devices in order to understand the sources of noise and reach better sensitivities. In this work, we are interested in the mass-sensing applications and will analyze their mechanics, both in the linear and nonlinear regimes. The treatment of nonlinearities is particularly challenging because there is no unique solution to the equation of motion. In addition, even if we do not perceive its characteristic bi-stability at room temperature, we still enter the nonlinear regime where the well-known models are no longer accurate. However, it is not easy to distinguish between the two regimes, since the linear model is only an approximation of the nonlinear model for small drives. The benefit of the nonlinear regime is that the received signal is stronger.There are several parameters to take into account (drive power, temperature,...), we studied some that affect the sensitivity to understand which are relevant for our system. We obtained a record-breaking sensitivity of 2x10⁻²⁵ g.We usually work at room temperature and cannot observe bi-stability, but we observed bi-stability when the temperature is lowered, which is in agreement with the theory that a small Q prevents hysteresis from appearing. With this in mind, it is interesting to have a low Q system at room temperature, as a sharper resonator would introduce additional noise due to bi-stability. We have therefore found a compromise between a large damping [3], which blocks hysteresis, and a sharp resonance, which gives precision.We achieved a record-breaking sensitivity at room temperature of 0.2 yg which is promising for future applications, given that the previous record sensitivity was reached in a cryostat [4].[1] K. L. Ekinci, M. L. Roukes. Nanoelectromechanical systems. Review of Scientific Instruments, (2005). https://doi.org/10.1063/1.1927327.[2] De Bonis, Sergio & Urgell, Carles & Yang, Wei & Samanta, C. & Noury, Adrien & Vergara-Cruz, J. & Dong, Quan & Jin, Yong & Bachtold, A.. (2018). Ultrasensitive Displacement Noise Measurement of Carbon Nanotube Mechanical Resonators. Nano Letters. 18. 10.1021/acs.nanolett.8b02437.[3] Swapan K. Roy et al. ,Improving mechanical sensor performance through larger damping.Science360,eaar5220(2018).DOI:10.1126/science.aar5220[4] Chaste, J., Eichler, A., Moser, J. et al. A nanomechanical mass sensor with yoctogram resolution. Nature Nanotech 7, 301–304 (2012). https://doi.org/10.1038/nnano.2012.42

This study investigates the influence of interlayer cations on the thermodynamics and sorption mechanisms of water in a reference Wyoming montmorillonite. The behaviour of the montmorillonite exchanged with monovalent cations (Li + , Na + , K + , Rb + , Cs + ) or divalent cations (Mg 2+ , Ca 2+ , Ba 2+ ) is compared. The analysis combines X-ray diffraction (XRD), water sorption isotherms at various temperatures and mid-infrared spectroscopy. Li + , Mg 2+ and Ca 2+ promote greater water uptake and swelling, whereas K + , Rb + and Cs + significantly limit these processes. The behaviour of Na + and Ba 2+ stands out, demonstrating intermediate water uptake and high swelling. Mid-infrared spectral analysis supports these observations. It is shown that a cation’s effect on water uptake and swelling correlates best with the product of its elementary charge and ionic radius rather than with other properties such as the electrostatic potential, solvation enthalpy or chemical hardness. However, differences in isotherm shapes, hysteresis between adsorption and desorption and the variation of isosteric heat with water content suggest the presence of two distinct sorption mechanisms: one involving Li + , Cs + , Mg 2+ , Ca 2+ and Ba 2+ , and another involving Na + , K + and Rb + . These findings indicate that isotherm shape and swelling alone do not directly reflect water uptake capacity. These findings thus outline that the chaotropic (structure-breaking) or kosmotropic (structure-making) nature of the cations, along with the complex interplay between cation hydration and TOT layer attraction, may explain the complex observed differences.

Hollow mesoporous organosilica (HMO) nanoparticles with a controlled core cavity and a mesoporous organosilica shell are elaborated , the synthesis steps are checked by IR spectroscopy, the HMO are then tested for endocytosis and biocompatibility.

We present a scalable solution-processing method for fabricating high-quality graphene and graphene/1T-MoS2 heterostructure films. The process begins with the synthesis of potassiumintercalated graphite (KC8), which is exfoliated in tetrahydrofuran (THF) to produce stable dispersions of negatively charged (electron rich) graphene sheets. The graphene is subsequently transferred to water, forming a surfactant-free aqueous dispersion suitable for creating homogenous graphene films via vacuum filtration and stamping. Additionally, graphene is combined with 1T-MoS2 nanosheets to fabricate graphene/1T-MoS2 bulk heterostructure films. Comprehensive characterization, including X-ray diffraction (XRD), absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photon emission spectroscopy (XPS), reveals that the heterostructure films exhibit enhanced optical and electronic properties, including improved light absorption, which could lead to novel photo-responsive devices. Raman spectroscopy shows significant changes in the graphene's structural and electronic properties upon interaction with MoS2, indicating strong interlayer coupling and potential charge transfer between the layered components. The graphene films demonstrate highly sensitive detection of dopamine (DA), while the graphene/1T-MoS2 bulk heterostructure films exhibit capacitance values up to 38.3

Fg -1 at 5 mV s -1 in non-aqueous electrolytes. These results highlight the potential of these films for advanced applications in molecular sensing and energy storage.