3D interdigitated microbattery architectures (3D-IMA) are fabricated by printing concentrated lithium oxide-based inks. The microbatteries are composed of interdigitated, high-aspect ratio cathode and anode structures. Our 3D-IMA, which exhibit high areal energy and power densities, may find potential application in autonomously powered microdevices.

Low-cost, high-yield production of graphene nanosheets (GNs) is essential for practical applications. We have achieved high yield of edge-selectively carboxylated graphite (ECG) by a simple ball milling of pristine graphite in the presence of dry ice. The resultant ECG is highly dispersable in various solvents to self-exfoliate into single-and few-layer (≤5 layers) GNs. These stable ECG (or GN) dispersions have been used for solution processing, coupled with thermal decarboxylation, to produce large-area GN films for many potential applications ranging from electronic materials to chemical catalysts. The electrical conductivity of a thermally decarboxylated ECG film was found to be as high as 1214 S∕cm, which is superior to its GO counterparts. Ball milling can thus provide simple, but efficient and versatile, and eco-friendly (CO 2 -capturing) approaches to low-cost mass production of high-quality GNs for applications where GOs have been exploited and beyond.carbon dioxide | eco-friendly | edge-functionalization | graphite A s a building block for carbon nanomaterials of all other dimensionalities, such as 0D buckyball, 1D nanotubes, and 3D graphite, graphene nanosheets (GNs) with carbon atoms densely packed in a 2D honeycomb crystal lattice have recently attracted tremendous interest for various potential applications (1). Several techniques, including the peel-off by Scotch tape (2), epitaxial growth on SiC (3), chemical vapor deposition (CVD) (4, 5), and solution exfoliation of graphite oxide (GO) (6), have been reported for producing GNs. Although the Scotch tape method led to the Nobel-Prize-winning discovery of high quality GNs (2), it is unsuitable for large-area preparation of GN films due to technique difficulties. On the other hand, large-area thin GN films up to 30 in. have been prepared by CVD (7). However, the CVD process involves extremely careful fabrication processes, which appears to be too tedious and too expensive for mass production. The widely reported solution exfoliation of graphite into GO, followed by solution reduction (8-10), allows the mass production of GNs via an all-solution process. Due to strong interactions between the hexagonally sp 2 -bonded carbon layers in graphite, however, the solution exfoliation requires the involvement of hazardous strong oxidizing reagents (e.g., HNO 3 , KMnO 4 , and/or H 2 SO 4 ) and a tedious multistep process (8,9,11,12). Such a corrosive chemical oxidation often causes severe damage to the carbon basal plane to introduce a large number of chemical and topological defects (13). As a result, postexfoliation reduction of GO into reduced graphene oxide (rGO) is essential in order to restore the graphitic basal plane for the resultant GNs (6,[14][15][16][17][18][19]. To make the matter worse, the reduction reaction also involves hazardous reducing reagents (e.g., hydrazine, NaBH 4 ) with a limited reduction conversion (approximately 70%) (20). The reduced GO (rGO) still contains considerable oxygenated groups and structural defects, and thus additional...

To replace precious platinum (Pt)-based electrocatalysts for cathodic oxygen reduction reaction (ORR), edge-selectively sulfurized graphene nanoplatelets (SGnP) are synthesized as efficient metal-free electrocatalysts simply by ball-milling pristine graphite in the presence of sulfur (S8 ). The resultant SGnPs exhibit remarkable electrocatalytic activity toward ORR with better tolerance to methanol crossover/CO poisoning effects and longer-term stability than those of pristine graphite and commercial Pt/C electrocatalysts. Edge-Selectively Sulfurized Graphene Nanoplatelets as Efficient Metal-Free Electrocatalysts for Oxygen Reduction Reaction: The Electron Spin Effect.

Edge-selectively functionalized graphene nanoplatelets (EFGnPs) with different functional groups were efficiently prepared simply by dry ball milling graphite in the presence of hydrogen, carbon dioxide, sulfur trioxide, or carbon dioxide/sulfur trioxide mixture. Upon exposure to air moisture, the resultant hydrogen- (HGnP), carboxylic acid- (CGnP), sulfonic acid- (SGnP), and carboxylic acid/sulfonic acid- (CSGnP) functionalized GnPs readily dispersed into various polar solvents, including neutral water. The resultant EFGnPs were then used as electrocatalysts for oxygen reduction reaction (ORR) in an alkaline electrolyte. It was found that the edge polar nature of the newly prepared EFGnPs without heteroatom doping into their basal plane played an important role in regulating the ORR efficiency with the electrocatalytic activity in the order of SGnP > CSGnP > CGnP > HGnP > pristine graphite. More importantly, the sulfur-containing SGnP and CSGnP were found to have a superior ORR performance to commercially available platinum-based electrocatalyst.

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Wearable electronics represent a significant paradigm shift in consumer electronics since they eliminate the necessity for separate carriage of devices. In particular, integration of flexible electronic devices with clothes, glasses, watches, and skin will bring new opportunities beyond what can be imagined by current inflexible counterparts. Although considerable progresses have been seen for wearable electronics, lithium rechargeable batteries, the power sources of the devices, do not keep pace with such progresses due to tenuous mechanical stabilities, causing them to remain as the limiting elements in the entire technology. Herein, we revisit the key components of the battery (current collector, binder, and separator) and replace them with the materials that support robust mechanical endurance of the battery. The final full-cells in the forms of clothes and watchstraps exhibited comparable electrochemical performance to those of conventional metal foil-based cells even under severe folding-unfolding motions simulating actual wearing conditions. Furthermore, the wearable textile battery was integrated with flexible and lightweight solar cells on the battery pouch to enable convenient solar-charging capabilities.

The formation of 2D polyaniline (PANI) has attracted considerable interest due to its expected electronic and optoelectronic properties. Although PANI was discovered over 150 y ago, obtaining an atomically well-defined 2D PANI framework has been a longstanding challenge. Here, we describe the synthesis of 2D PANI via the direct pyrolysis of hexaaminobenzene trihydrochloride single crystals in solid state. The 2D PANI consists of three phenyl rings sharing six nitrogen atoms, and its structural unit has the empirical formula of C 3 N. The topological and electronic structures of the 2D PANI were revealed by scanning tunneling microscopy and scanning tunneling spectroscopy combined with a first-principle density functional theory calculation. The electronic properties of pristine 2D PANI films (undoped) showed ambipolar behaviors with a Dirac point of -37 V and an average conductivity of 0.72 S/cm. After doping with hydrochloric acid, the conductivity jumped to 1.41 × 10 3 S/cm, which is the highest value for doped PANI reported to date. Although the structure of 2D PANI is analogous to graphene, it contains uniformly distributed nitrogen atoms for multifunctionality; hence, we anticipate that 2D PANI has strong potential, from wet chemistry to device applications, beyond linear PANI and other 2D materials.was discovered in 1834 (1), the word PANI was first coined in 1947 (2), and PANI garnered immense attention from the scientific community due to its intrinsically conducting nature (3). During the last three decades, PANI has been one of the most extensively studied conducting polymers because of its simple synthesis, low cost, high conductivity, environmental stability, and doping chemistry (4, 5). Linear PANI has found broad applicability in rechargeable batteries (6), electromagnetic shielding (7), nonlinear optics (8), light-emitting devices (9), sensors (10), field effect transistors (11), erasable optical information storage (12), membranes (13), digital memory devices (14) (27)], cyclic, spiral, and complex nanostructures have also been reported (28). However, due to the mechanistic complexity of aniline polymerization, the atomic-scale control of PANI structure has not yet been realized (28). Together with the recent discovery of all-carbon-based 2D graphene and its promising potentials (29), 2D network polymers are galvanizing a new wave of research in the scientific community (30). Here, we, for the first time to our knowledge, report the synthesis of real 2D PANI framework from direct pyrolysis of organic single crystals, hexaaminobenzene trihydrochloride (HAB), at 500°C. This synthetic methodology could serve as a straightforward way for the design and synthesis of other new 2D layered materials with many potential applications, from wet chemistry to devices. Results and DiscussionThe key building block, HAB, as a monomer with six functional groups (M6), was synthesized in a pure crystalline form (Fig. 1A and SI Appendix, Fig. S1) (31). It was observed that the HAB single crystals pyrolyze before mel...

The outstanding performance (sheet resistance of 5 Ω sq at transmittance of 90%) and strongly adhesive (30.7 J m ) silver nanowires (AgNWs) are fabricated using flash-induced plasmonic welding (FPW) based on theoretical research of photothermal interactions. The FPW-processed AgNWs are utilized as electrodes of a transparent flexible energy harvester, and this device exhibits excellent transmittance and high electric output performance. The FPW methodology provides a high-tech solution for transparent flexible electronics.