RESUMO
Two-dimensional transition metal carbides, that is, MXenes and especially Ti3C2, attract attention due to their excellent combination of properties. Ti3C2 nanosheets could be the material of choice for future flexible electronics, energy storage, and electromechanical nanodevices. There has been limited information available on the mechanical properties of Ti3C2, which is essential for their utilization. We have fabricated Ti3C2 nanosheets and studied their mechanical properties using direct in situ tensile tests inside a transmission electron microscope, quantitative nanomechanical mapping, and theoretical calculations employing machine-learning derived potentials. Young's modulus in the direction perpendicular to the Ti3C2 basal plane was found to be 80-100 GPa. The tensile strength of Ti3C2 nanosheets reached up to 670 MPa for â¼40 nm thin nanoflakes, while a strong dependence of tensile strength on nanosheet thickness was demonstrated. Theoretical calculations allowed us to study mechanical characteristics of Ti3C2 as a function of nanosheet geometrical parameters and structural defect concentration.
RESUMO
In situ transmission electron microscopy (TEM) is one of the most powerful approaches for revealing physical and chemical process dynamics at atomic resolutions. The most recent developments for in situ TEM techniques are summarized; in particular, how they enable visualization of various events, measure properties, and solve problems in the field of energy by revealing detailed mechanisms at the nanoscale. Related applications include rechargeable batteries such as Li-ion, Na-ion, Li-O2 , Na-O2 , Li-S, etc., fuel cells, thermoelectrics, photovoltaics, and photocatalysis. To promote various applications, the methods of introducing the in situ stimuli of heating, cooling, electrical biasing, light illumination, and liquid and gas environments are discussed. The progress of recent in situ TEM in energy applications should inspire future research on new energy materials in diverse energy-related areas.