Aerosol Jet Printing of Graphene and Carbon Nanotube Patterns on Realistically Rugged Substrates

Direct-write additive manufacturing of graphene and carbon nanotube (CNT) patterns by aerosol jet printing (AJP) is promising for the creation of thermal and electrical interconnects in (opto)electronics. In realistic application scenarios, this however often requires deposition of graphene and CNT patterns on rugged substrates such as, for example, roughly machined and surface oxidized metal block heat sinks. Most AJP of graphene/CNT patterns has thus far however concentrated on flat wafer-or foil type substrates. Here, we demonstrate AJP of graphene and single walled CNT (SWCNT) patterns on realistically rugged plasma electrolytic-oxidized (PEO) Al blocks, which are promising heat sink materials. We show that AJP on the rugged substrates offers line resolution of down to similar to 40 mu m width for single AJP passes, however, at the cost of noncomplete substrate coverage including noncovered mu m-sized pores in the PEO Al blocks. With multiple AJP passes, full coverage including coverage of the pores is, however, readily achieved. Comparing archetypical aqueous and organic graphene and SWCNT inks, we show that the choice of the ink system drastically influences the nanocarbon AJP parameter window, deposit microstructure including crystalline quality, compactness of deposit, and inter/intrapass layer adhesion for multiple passes. Simple electrical characterization indicates aqueous graphene inks as the most promising choice for AJP-deposited electrical interconnect applications. Our parameter space screening thereby forms a framework for rational process development for graphene and SWCNT AJP on application-relevant, rugged substrates

Curcumin Induced Human Gastric Cancer BGC-823 Cells Apoptosis by ROS-Mediated ASK1-MKK4-JNK Stress Signaling Pathway

The signaling mediated by stress-activated MAP kinases (MAPK), c-Jun N-terminal kinase (JNK) has well-established importance in cancer. In the present report, we investigated the effects of curcumin on the signaling pathway in human gastric cancer BGC-823 cells. Curcumin induced reactive oxygen species (ROS) production and BGC-823 cells apoptosis. Inhibition of ROS generation by antioxidant (NAC or Trion) significantly prevented curcumin-mediated apoptosis. Notably, we observed that curcumin activated ASK1, a MAPKKK that is oxidative stress sensitive and responsible to phosphorylation of JNK via triggering cascades, up-regulated an upstream effector of the JNK, MKK4, and phosphorylated JNK protein expression in BGC-823 cells. However, curcumin induced ASK1-MKK4-JNK signaling was attenuated by NAC. All the findings confirm the possibility that oxidative stress-activated ASK1-MKK4-JNK signaling cascade promotes the apoptotic response in curcumin-treated BGC-823 cells

Ultrahigh-voltage integrated micro-supercapacitors with designable shapes and superior flexibility

With the development of power source-integrated electronics, the miniaturization of high-voltage integrated micro-supercapacitors (IMSCs) with multiple innovative form factors is urgently required but remains unsolved. Here, we demonstrate a universal, costeffective, industrially applicable protocol for fast and scalable fabrication of graphene-based planar IMSCs, with shape diversity, aesthetic versatility, outstanding flexibility and superior modularization. Using highly-conducting graphene ink, we directly screenprint shape-designable IMSCs in several seconds, consisting of hundreds to thousands of individual MSCs on arbitrary substrates. The resulting IMSCs are free of external metal current collectors and interconnects as well as separators, and exhibit exceptional electrical double-layer capacitive behaviors and remarkable flexibility. Notably, the output voltage and capacitance of IMSCs are readily adjustable through connection in well-defined arrangements of MSCs. As a proof of concept, a tandem energy storage pack of IMSCs with 130 MSCs can output a recorded voltage exceeding 100 V, demonstrative of superior modularization and performance uniformity

In situ assembly of multi-sheeted buckybooks from single-walled carbon nanotubes

We report a simple approach for the direct and nondestructive assembly of multi-sheeted singlewalled carbon nanotube book-like macrostructures (buckybooks) with good control of the nanotube diameter, the sheet packing density, and the book thickness during the floating catalytic growth process. The promise of such buckybooks is highlighted by demonstrating their high capacitance and high-efficiency molecular separation by directly using them as a binder-free electrode and as a filter, respectively. Our approach also provides a flexible and reliable way to easily assemble various other types of nanotubes into book-like or even more sophisticated sandwich-like hybrid macrostructures, realizing the shape-engineering of one-dimensional nanostructures to macroscopic well-defined architectures for various applications.</p

Aerosol Jet Printed Nanocarbons on Heat Sink Materials

Graphene- and carbon nanotube (CNT)-based inks have been printed on relevant heat sink materials by Aerosol jet. The thickness of the layers varied between ~100 and ~1.500 nm. The inks’ viscosity ranged from &lt;20 up to 600 cps at a solid content between 0.18 and 3% and wide particle sizes from 5 nm up to 5 µm. The printed layers could be interesting for rather high-power and high-temperature applications including thermal heat spreaders, resistive heaters, high-current carrying interconnectors, temperature sensors and ordnance fuze technology

Fibrous Hybrid of Graphene and Sulfur Nanocrystals for High-Performance Lithium–Sulfur Batteries

Graphene–sulfur (G–S) hybrid materials with sulfur nanocrystals anchored on interconnected fibrous graphene are obtained by a facile one-pot strategy using a sulfur/carbon disulfide/alcohol mixed solution. The reduction of graphene oxide and the formation/binding of sulfur nanocrystals were integrated. The G–S hybrids exhibit a highly porous network structure constructed by fibrous graphene, many electrically conducting pathways, and easily tunable sulfur content, which can be cut and pressed into pellets to be directly used as lithium–sulfur battery cathodes without using a metal current-collector, binder, and conductive additive. The porous network and sulfur nanocrystals enable rapid ion transport and short Li⁺ diffusion distance, the interconnected fibrous graphene provides highly conductive electron transport pathways, and the oxygen-containing (mainly hydroxyl/epoxide) groups show strong binding with polysulfides, preventing their dissolution into the electrolyte based on first-principles calculations. As a result, the G–S hybrids show a high capacity, an excellent high-rate performance, and a long life over 100 cycles. These results demonstrate the great potential of this unique hybrid structure as cathodes for high-performance lithium–sulfur batteries

Toward More Reliable Lithium–Sulfur Batteries: An All-Graphene Cathode Structure

Lithium–sulfur (Li–S) batteries are attracting increasing interest due to their high theoretical specific energy density, low cost, and eco-friendliness. However, most reports of the high gravimetric specific capacity and long cyclic life are not practically reliable because of their low areal specific capacity derived from the low areal sulfur loading and low sulfur content. Here, we fabricated a highly porous graphene with high pore volume of 3.51 cm³ g^–1 as the sulfur host, enabling a high sulfur content of 80 wt %, and based on this, we further proposed an all-graphene structure for the sulfur cathode with highly conductive graphene as the current collector and partially oxygenated graphene as a polysulfide-adsorption layer. This cathode structural design enables a 5 mg cm^–2 sulfur-loaded cathode showing both high initial gravimetric specific capacity (1500 mAh g^–1) and areal specific capacity (7.5 mAh cm^–2), together with excellent cycling stability for 400 cycles, indicating great promise for more reliable lithium–sulfur batteries