As an emerging class of materials, nanocarbons have attracted significant interest for practical applications due to their remarkable mechanical, electrical and thermal properties coupled with high surface areas and tunable surface chemistry. However, challenges like high aspect ratios and poor dispersibility in polymer matrices hinder their widespread use in technological applications. The problems are most prominently resolved with the use of free-standing nanocarbon sheets. The present paper reviews recent advancements in fabricating and utilizing free-standing sheets consisting of various nanocarbons: carbon nanotubes and 2D materials like graphene, graphene oxide, and reduced graphene oxide. It initially delves into the nanomechanics of these sheets, focusing on inter-particle cross-linking and nacre-like microstructures. Energy storage applications are also examined, with emphasis on the role of nanocarbon-based sheets in the enhancement of specific energy capacity and performance retention of batteries, electric double layer supercapacitors, and pseudocapacitors. In the field of electromagnetic interference shielding, the sheets' superior electrical conductivity and microstructures, which amplify internal reflections in the GHz and THz regions, are showcased. Their potential in heat dissipation, owing to their high thermal conductivity and large surface area, is also explored. Additionally, they are reviewed for membrane-based separation processes, specifically gas separation, reverse osmosis, forward osmosis, and pervaporation, highlighting properties like ion selectivity and chlorine resistance. The last discussion concerns the role of nanocarbon-based sheets in catalysis where they can enhance reaction efficiencies and promote sustainable solutions. Either as catalysts and/or supports, with key features such as high surface area, electrical conductivity, and adaptable functionalities, they showcase significant potential in various catalytic processes like electrocatalysis and environmental remediation.

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Graphene, with its superior physical properties, has been considered as the perfect candidate for the production of lightweight, high-strength composite materials with interesting multi-functionalities. The use of large-sized, high-quality CVD graphene monolayers alternated to ultra-thin polymer films in a laminate configuration has been recently proposed as an efficient route to overcome many of the limitations faced by the use of discontinuous sheets of graphene in nanocomposites. Here we report on the production of CVD graphene/polyetherimide (Gr/PEI) nanolaminates with very low graphene volume fractions (up to 0.165 vol%), using a modified iterative and automatic lift-off/float-on procedure. The produced freestanding Gr/PEI nanolaminates present not only a significant enhancement of mechanical and electrical properties but, very interestingly, show impressive Joule heating efficiency. In fact, upon the application of an electrical potential, they can reach temperatures higher than 250 °C, with heating rates up to 325 °C/s. The produced heaters show a very uniform distribution of the temperature even when bend and are characterized by low power consumptions (up to 16 Watt) and high areal power densities (up to ca. ∼1.28 W/cm2), thus suggesting their possible application in thermal management.@en