Graphene aerogel microlattices (GAMs) hold great prospects for many multifunctional applications due to their low density, high porosity, designed lattice structures, good elasticity, and tunable electrical conductivity. Previous 3D printing approaches to fabricate GAMs require either high content of additives or complex processes, limiting their wide applications. Here, a facile ion‐induced gelation method is demonstrated to directly print GAMs from graphene oxide (GO) based ink. With trace addition of Ca2+ ions as gelators, aqueous GO sol converts to printable gel ink. Self‐standing 3D structures with programmable microlattices are directly printed just in air at room temperature. The rich hierarchical pores and high electrical conductivity of GAMs bring admirable capacitive performance for supercapacitors. The gravimetric capacitance (Cs) of GAMs is 213 F g−1 at 0.5 A g−1 and 183 F g−1 at 100 A g−1, and retains over 90% after 50 000 cycles. The facile, direct 3D printing of neat graphene oxide can promote wide applications of GAMs from energy storage to tissue engineering scaffolds.

A sort of novel high-flux nanofiltration membrane was fabricated by synergistic assembling of graphene and multiwalled carbon nanotubes (MWNTs), in which graphene played the role of molecular sieving and MWNTs expanded the interlayer space between neighbored graphene sheets. The MWNT-intercalated graphene nanofiltration membrane (G-CNTm) showed a water flux up to 11.3 L m(-2) h(-1) bar(-1), more than 2 times that of the neat graphene nanofiltration membrane (GNm), while keeping high dye rejection (>99% for Direct Yellow and >96% Methyl Orange). The G-CNTm also showed good rejection ratio for salt ions (i.e., 83.5% for Na2SO4, 51.4% for NaCl). We also explored the antifouling performance of G-CNTm and GNm with bovine serum albumin (BSA), sodium alginate (SA) and humic acid (HA). Both G-CNTm and GNm possessed excellent antifouling performance for SA and HA but inferior for BSA because of the strong interaction between protein and graphene sheets.

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.

We report on the vibrational population and orientational relaxation dynamics of 1 -methylperylene in the series of normal alkanes n-pentane through n-decane, n-dodecane, and n-hexadecane. We find that both the vibrational population relaxation time constant, T I , of the 1-methylperylene 1370 cm-' mode and the orientational relaxation time constant( s), ror, depend sensitively and nonlinearly on the aliphatic chain length of the n-alkane solvent. The data show that the two relaxations are sensitive to solvent local organization on approximately the same length scale and stand in contrast to our recent reports on the relaxation dynamics of perylene in the same n-alkane solvents (1. Phys. Chem. 1994, 98,6436; 1994,98,941 l), where the operative length scale of TI relaxation was found to be substantially shorter than the length of the perylene molecule. We understand these differences in the context of the different polar v-v coupling processes utilized by perylene and 1-methylperylene. The rotational diffusion data for 1 -methylperylene indicate that the dominant reorientation axis of the chromophore changes with solvent aliphatic chain length.

Aqueous rechargeable batteries are highly safe, low‐cost, and environmentally friendly, but restricted by low energy density. One of the most efficient solutions is to improve the concentration of the aqueous electrolytes. However, each salt is limited by its physical solubility, generally below 21–32 mol kg−1 (m). Here, a ZnCl2/ZnBr2/Zn(OAc)2 aqueous electrolyte with a record super‐solubility up to 75 m is reported, which breaks through the physical solubility limit. This is attributed to the formation of acetate‐capped water–salt oligomers bridged by Br−/Cl−‐H and Br−/Cl−/O‐Zn2+ interactions. Mass spectrometry indicates that acetate anions containing nonpolarized protons prohibit the overgrowth and precipitation of ionic oligomers. The polymer‐like glass transition temperature of such inorganic electrolytes is found at ≈−70 to −60 °C, without the observation of peaks for salt‐crystallization and water‐freezing from 40 to −80 °C. This supersoluble electrolyte enables high‐performance aqueous dual‐ion batteries that exhibit a reversible capacity of 605.7 mAh g−1, corresponding to an energy density of 908.5 Wh kg−1, with a coulombic efficiency of 98.07%. In situ X‐ray diffraction and Raman technologies reveal that such high ionic concentrations of the supersoluble electrolyte enable a stage‐1 intercalation of bromine into macroscopically assembled graphene cathode.

We have measured the vibrational population relaxation times of the Raman active v7 mode (1375 cm-') and(v7 + v15) combination mode (1733 cm-') of perylene in eight liquid n-alkanes using ultrafast stimulated emission spectroscopy. The vibrational population relaxation time of the perylene v7 mode ranges from -300 to < l o ps depending on the n-alkane solvent chain length, but there is no simple correspondence between alkane length and TI for v7. Energy transfer from the perylene v7 vibrational mode to a specific n-alkane solvent vibrational mode is dominated by long-range resonance coupling. The perylene (v7 + ~1 5 ) combination mode exhibits additional efficient relaxation pathways for different length n-alkanes. These data point collectively to short-range order in the n-alkane solvent surrounding perylene molecule. IntroductionThere have been a large number of recent studies focusing on intermolecular interactions in room temperature liquids because they are an important but ill-understood vehicle for many chemical processes.' Principal among the difficulties associated with understanding intermolecular interactions in liquids is the rapidly changing spatial relationship between neighboring molecules and elucidation of the various pathways in which energy can be exchanged. There are a variety of length scales on which these questions can be addressed, and the information provided by experiments aimed at interrogating the various length scales, taken collectively, can provide insight into local, transient organization in liquids.The advent of lasers capable of producing short pulses of light has allowed the direct investigation of energy and structural relaxation processes in liquids. A common theme in many laserbased experiments on liquid-phase dynamics is the use of a "probe" molecule that absorbs and (sometimes) emits light at wavelengths accessible to pulsed lasers. For almost all of these experiments, there is excess energy remaining in the probe molecule after the information of interest has been extracted, and at least some of this excess energy is stored as vibrational energy. In low-pressure gas-phase experiments, where an excited molecule is comparatively isolated from its neighbors, vibrational energy will dissipate slowly within the molecule to lower energy modes according to the extent of anharmonic coupling between the vibrational modes.2 For probe molecules in liquids, intramolecular relaxation is often less important than direct intermolecular relaxation because the number of collisional interactions with the surrounding medium is large and individual molecules are in closer spatial proximity to one a n~t h e r .~.~ In solution, excess vibrational energy within a molecule can be dissipated directly into the surroundings, sometimes very efficiently. Intermolecular vibrational population relaxation processes include energy transfer from solute vibrational modes into the translational, vibrational, and rota-* Author to whom correspondence should be addressed. @ Abstract published in Advance ACS Ab...

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Shape memory polymers (SMPs) change shapes as-designed through altering the chain segment movement by external stimuli, promising wide uses in actuators, sensors, drug delivery, and deployable devices. However, the recovery speed of SMPs is still far slower than the benchmark shape memory alloys (SMAs), originating from their intrinsic poor heat transport and retarded viscoelasticity of polymer chains. In this work, monolithic nanocomposite aerogels composed of bicontinuous graphene and SMP networks are designed to promote the recovery time of SMP composites to a record value of 50 ms, comparable to the SMA case. The integration of a stretchable graphene framework as a fast energy transformation grid with ultrathin polycaprolactone nanofilms (tunable at 2.5−60 nm) enables the rapid phase transition of SMPs under electrical stimulation. The graphene−SMP nanocomposite aerogels, with a density of ∼10 mg cm −3 , exhibit a fast response (175 ± 40 mm s −1 ), large deformation (∼100%), and a wide response bandwidth (0.1−20 Hz). The ultrafast response of SMP nanocomposite aerogels confers extensive uses in sensitive fuses, micro-oscillators, artificial muscles, actuators, and soft robotics. The design of bicontinuous ultralight aerogels can be extended to fabricate multifunctional and multiresponsive hybrid materials and devices.