Carbon aerogels demonstrate wide applications for their ultralow density, rich porosity, and multifunctionalities. Their compressive elasticity has been achieved by different carbons. However, reversibly high stretchability of neat carbon aerogels is still a great challenge owing to their extremely dilute brittle interconnections and poorly ductile cells. Here we report highly stretchable neat carbon aerogels with a retractable 200% elongation through hierarchical synergistic assembly. The hierarchical buckled structures and synergistic reinforcement between graphene and carbon nanotubes enable a temperature-invariable, recoverable stretching elasticity with small energy dissipation (~0.1, 100% strain) and high fatigue resistance more than 106 cycles. The ultralight carbon aerogels with both stretchability and compressibility were designed as strain sensors for logic identification of sophisticated shape conversions. Our methodology paves the way to highly stretchable carbon and neat inorganic materials with extensive applications in aerospace, smart robots, and wearable devices.

Using low-pressure chemical vapor deposition (LPCVD), we, for the first time, realize the self-limiting growth behavior of monolayer graphene on commercially available electroplated copper foils from a carbon precursor other than methane, and systematically investigate the growth of graphene from ethanol and compare its self-limiting behavior over copper facets with different identities. Results show that the growth of graphene from ethanol in the LPCVD process is a substratemediated process, in which the domains of graphene are determined by the lattice axes on the copper facets. Moreover, during the evolution of the domains, low-index copper facets of Cu(111) and Cu(100) play a critical role in the following self-limiting process of a continuous graphene sheet, whereas the Cu(110) and high-index facets favor nucleation and formation of secondary layers. In addition, a high degree of similarity exists between graphene grown from ethanol and methane, showing that, when the carbon flux is sufficiently low, the self-limiting growth of graphene on copper surfaces using LPCVD is independent of the precursor structure of ethanol and methane.

A computationally efficient mode space simulation method for atomistic simulation of a graphene nanoribbon field-effect transistor in the ballistic limits is developed. The proposed simulation scheme, which solves the nonequilibrium Green's function coupled with a three dimensional Poisson equation, is based on the atomistic Hamiltonian in a decoupled mode space. The mode space approach, which only treats a few modes (subbands), significantly reduces the simulation time. Additionally, the edge bond relaxation and the third nearest neighbor effects are also included in the quantum transport solver. Simulation examples show that, mode space approach can significantly decrease the simulation cost by about an order of magnitude, yet the results are still accurate. This article also demonstrates that the effects of edge bond relaxation and third nearest neighbor significantly influence the transistor's performance and are necessary to be included in the modeling.

High-performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine-functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid-infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp domains, and the trapping of photoexcited charge carriers in the localized states in sp domains. Tunable photoresponse is achieved by controlling the nature of sp sites and the size and fraction of sp /sp domains. In addition, the photoresponse due to the different photoexcited-charge-carrier trapping times in sp and sp nanodomains is determined. The proposed scheme paves the way toward implementing high-performance broadband graphene-based photodetectors.

Using ethanol as the carbon source, self-limiting growth of AB-stacked bilayer graphene (BLG) has been achieved on Cu via an equilibrium chemical vapor deposition (CVD) process. We found that during this alcohol catalytic CVD (ACCVD) a source-gas pressure range exists to break the self-limitation of monolayer graphene on Cu, and at a certain equilibrium state it prefers to form uniform BLG with a high surface coverage of ∼94% and AB-stacking ratio of nearly 100%. More importantly, once the BLG is completed, this growth shows a self-limiting manner, and an extended ethanol flow time does not result in additional layers. We investigate the mechanism of this equilibrium BLG growth using isotopically labeled (13)C-ethanol and selective surface aryl functionalization, and results reveal that during the equilibrium ACCVD process a continuous substitution of graphene flakes occurs to the as-formed graphene and the BLG growth follows a layer-by-layer epitaxy mechanism. These phenomena are significantly in contrast to those observed for previously reported BLG growth using methane as precursor.

a b s t r a c tWe show that graphene single crystals as large as 5 mm can be synthesized from ethanol via chemical vapor deposition (CVD). Key conditions for the successful reduction in nucleation density are extremely low partial pressure of ethanol vapor and pre-oxidation of Cu substrates. The resulting graphene flakes are predominantly homogeneous single-layer hexagons, as characterized by Raman spectroscopy and selected area electron diffraction. However, the edge of ethanol produced graphene shows an armchair feature, suggesting a possible different mechanism from conventional methane CVD.

An ultrahigh arsenic uptake capacity was achieved using a hierarchically porous UiO-66 with tunable mesopores and active sites.

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