Flexible Nanoporous WO3-x Nonvolatile Memory Device.

Flexible resistive random access memory (RRAM) devices have attracted great interest for future nonvolatile memories. However, making active layer films at high temperature can be a hindrance to RRAM device fabrication on flexible substrates. Here, we introduced a flexible nanoporous (NP) WO3-x RRAM device using anodic treatment in a room-temperature process.

Mechanistic understanding of calcium-phosphonate solid dissolution and scale inhibitor return behavior in oilfield reservoir: formation of middle phase.

Phosphonates are an important class of mineral scale inhibitors used for oilfield scale control. By injecting the phosphonate into an oilfield reservoir, calcium-phosphonate precipitate will form and subsequently release the phosphonate into produced water for scale control. In this study, a systematic procedure is developed to mechanistically characterize an acidic calcium-phosphonate amorphous material that is later developed into a middle phase and eventually a crystalline phase.

Growth and Transfer of Seamless 3D Graphene-Nanotube Hybrids.

Seamlessly connected graphene and carbon nanotube hybrids (GCNTs) have great potential as carbon platform structures in electronics due to their high conductivity and high surface area. Here, we introduce a facile method for making patterned GCNTs and their intact transfer onto other substrates. The mechanism for selective growth of vertically aligned CNTs (VA-CNTs) on the patterned graphene is discussed.

High-Performance Pseudocapacitive Microsupercapacitors from Laser-Induced Graphene.

All-solid-state, flexible, symmetric, and asymmetric microsupercapacitors are fabricated by a simple method in a scalable fashion from laser-induced graphene on commercial polyimide films, followed by electrodeposition of pseudocapacitive materials on the interdigitated in-plane architectures. These microsupercapacitors demonstrate comparable energy density to commercial lithium thin-film batteries, yet exhibit more than two orders of magnitude higher power density with good mechanical flexibility.

Unimolecular Submersible Nanomachines. Synthesis, Actuation, and Monitoring.

Unimolecular submersible nanomachines (USNs) bearing light-driven motors and fluorophores are synthesized. NMR experiments demonstrate that the rotation of the motor is not quenched by the fluorophore and that the motor behaves in the same manner as the corresponding motor without attached fluorophores. No photo or thermal decomposition is observed.

Carbon-Free Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions.

A nanoporous Ag-embedded SnO2 thin film was fabricated by anodic treatment of electrodeposited Ag-Sn alloy layers. The ordered nanoporous structure formed by anodization played a key role in enhancing the electrocatalytic performance of the Ag-embedded SnO2 layer in several ways: (1) the roughness factor of the thin film is greatly increased from 23 in the compact layer to 145 in the nanoporous layer, creating additional active sites that are involved in oxygen electrochemical reactions; (2) a trace amount of Ag (∼1.7 at %, corresponding to a Ag loading of ∼3.

Three-Dimensional Networked Nanoporous Ta2O(5-x) Memory System for Ultrahigh Density Storage.

Oxide-based resistive memory systems have high near-term promise for use in nonvolatile memory. Here we introduce a memory system employing a three-dimensional (3D) networked nanoporous (NP) Ta2O5-x structure and graphene for ultrahigh density storage. The devices exhibit a self-embedded highly nonlinear I-V switching behavior with an extremely low leakage current (on the order of pA) and good endurance.

Porous cobalt-based thin film as a bifunctional catalyst for hydrogen generation and oxygen generation.

A mixed-phased Co-based catalyst composed of Co phosphide and Co phosphate is successfully fabricated for bifunctional water electrolysis. The highly porous morphology in this anodized film enables efficient catalytic activity toward water splitting in an extremely low loading mass. The mixed phases in the porous film afford an ability to generate both H2 and O2 in a single electrolyzer.

Cobalt nanoparticles embedded in nitrogen-doped carbon for the hydrogen evolution reaction.

There is great interest in renewable and sustainable energy research to develop low-cost, highly efficient, and stable electrocatalysts as alternatives to replace Pt-based catalysts for the hydrogen evolution reaction (HER). Though nanoparticles encapsulated in carbon shells have been widely used to improve the electrode performances in energy storage devices (e.g.

Asphalt-derived high surface area activated porous carbons for carbon dioxide capture.

Research activity toward the development of new sorbents for carbon dioxide (CO2) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO2 uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source.

Edge-oriented MoS2 nanoporous films as flexible electrodes for hydrogen evolution reactions and supercapacitor devices.

A simple method to fabricate edge-oriented MoS2 films with sponge-like morphologies is demonstrated. They are directly fabricated through the reaction of sulfur vapor with anodically formed Mo oxide sponge-like films on flexible Mo substrates. The edge-oriented MoS2 film delivers excellent hydrogen evolution reaction (HER) activity with enhanced kinetics and long-term cycling stability.

Hydrothermally formed three-dimensional nanoporous Ni(OH)2 thin-film supercapacitors.

A three-dimensional nanoporous Ni(OH)2 thin-film was hydrothermally converted from an anodically formed porous layer of nickel fluoride/oxide. The nanoporous Ni(OH)2 thin-films can be used as additive-free electrodes for energy storage. The nanoporous layer delivers a high capacitance of 1765 F g(-1) under three electrode testing.

Enhanced cycling stability of lithium sulfur batteries using sulfur-polyaniline-graphene nanoribbon composite cathodes.

A hierarchical nanocomposite material of graphene nanoribbons combined with polyaniline and sulfur using an inexpensive, simple method has been developed. The resulting composite, characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron microscopy, and X-ray diffraction analysis, has a good rate performance and excellent cycling stability. The synergistic combination of electrically conductive graphene nanoribbons, polyaniline, and sulfur produces a composite with high performance.

Efficient electrocatalytic oxygen evolution on amorphous nickel-cobalt binary oxide nanoporous layers.

Nanoporous Ni-Co binary oxide layers were electrochemically fabricated by deposition followed by anodization, which produced an amorphous layered structure that could act as an efficient electrocatalyst for water oxidation. The highly porous morphologies produced higher electrochemically active surface areas, while the amorphous structure supplied abundant defect sites for oxygen evolution. These Ni-rich (10-40 atom % Co) binary oxides have an increased active surface area (roughness factor up to 17), reduced charge transfer resistance, lowered overpotential (∼325 mV) that produced a 10 mA cm(-2) current density, and a decreased Tafel slope (∼39 mV decade(-1)).

Nanoporous silicon oxide memory.

Oxide-based two-terminal resistive random access memory (RRAM) is considered one of the most promising candidates for next-generation nonvolatile memory. We introduce here a new RRAM memory structure employing a nanoporous (NP) silicon oxide (SiOx) material which enables unipolar switching through its internal vertical nanogap. Through the control of the stochastic filament formation at low voltage, the NP SiOx memory exhibited an extremely low electroforming voltage (∼ 1.

Three-dimensional thin film for lithium-ion batteries and supercapacitors.

Three-dimensional heterogeneously nanostructured thin-film electrodes were fabricated by using Ta2O5 nanotubes as a framework to support carbon-onion-coated Fe2O3 nanoparticles along the surface of the nanotubes. Carbon onion layers function as microelectrodes to separate the two different metal oxides and form a nanoscale 3-D sandwich structure. In this way, space-charge layers were formed at the phase boundaries, and it provides additional energy storage by charge separation.

Graphene nanoribbon/V2O5 cathodes in lithium-ion batteries.

Nanocrystalline V2O5 particles were successfully entrapped by graphene nanoribbons (GNRs) derived from unzipped carbon nanotubes. The electrical conductivity of V2O5 nanoparticles was enhanced after introducing the GNRs. The 3-dimensional conductive framework in the composites plays a significant role in improving the rate performance and cyclability of the material when used as a cathode in lithium-ion batteries.

Flexible three-dimensional nanoporous metal-based energy devices.

A flexible three-dimensional (3-D) nanoporous NiF2-dominant layer on poly(ethylene terephthalate) has been developed. The nanoporous layer itself can be freestanding without adding any supporting carbon materials or conducting polymers. By assembling the nanoporous layer into two-electrode symmetric devices, the inorganic material delivers battery-like thin-film supercapacitive performance with a maximum capacitance of 66 mF cm(-2) (733 F cm(-3) or 358 F g(-1)), energy density of 384 Wh kg(-1), and power density of 112 kW kg(-1).

Carbon-based nanoreporters designed for subsurface hydrogen sulfide detection.

Polyvinyl alcohol functionalized carbon black with H2S-sensor moieties can be pumped through oil and water in porous rock and the H2S content can be determined based on the fluorescent enhancement of the H2S-sensor addends.

Rebar graphene.

As the cylindrical sp(2)-bonded carbon allotrope, carbon nanotubes (CNTs) have been widely used to reinforce bulk materials such as polymers, ceramics, and metals. However, both the concept demonstration and the fundamental understanding on how 1D CNTs reinforce atomically thin 2D layered materials, such as graphene, are still absent. Here, we demonstrate the successful synthesis of CNT-toughened graphene by simply annealing functionalized CNTs on Cu foils without needing to introduce extraneous carbon sources.

Three-dimensional nanoporous Fe₂O₃/Fe₃C-graphene heterogeneous thin films for lithium-ion batteries.

Three-dimensional self-organized nanoporous thin films integrated into a heterogeneous Fe2O3/Fe3C-graphene structure were fabricated using chemical vapor deposition. Few-layer graphene coated on the nanoporous thin film was used as a conductive passivation layer, and Fe3C was introduced to improve capacity retention and stability of the nanoporous layer. A possible interfacial lithium storage effect was anticipated to provide additional charge storage in the electrode.

Coal as an abundant source of graphene quantum dots.

Coal is the most abundant and readily combustible energy resource being used worldwide. However, its structural characteristic creates a perception that coal is only useful for producing energy via burning. Here we report a facile approach to synthesize tunable graphene quantum dots from various types of coal, and establish that the unique coal structure has an advantage over pure sp2-carbon allotropes for producing quantum dots.

Functionalized low defect graphene nanoribbons and polyurethane composite film for improved gas barrier and mechanical performances.

A thermoplastic polyurethane (TPU) composite film containing hexadecyl-functionalized low-defect graphene nanoribbons (HD-GNRs) was produced by solution casting. The HD-GNRs were well distributed within the polyurethane matrix, leading to phase separation of the TPU. Nitrogen gas effective diffusivity of TPU was decreased by 3 orders of magnitude with only 0.

Graphene nanoribbon and nanostructured SnO2 composite anodes for lithium ion batteries.

A composite made from graphene nanoribbons (GNRs) and tin oxide (SnO2) nanoparticles (NPs) is synthesized and used as the anode material for lithium ion batteries (LIBs). The conductive GNRs, prepared using sodium/potassium unzipping of multiwall carbon nanotubes, can boost the lithium storage performance of SnO2 NPs. The composite, as an anode material for LIBs, exhibits reversible capacities of over 1520 and 1130 mAh/g for the first discharge and charge, respectively, which is more than the theoretical capacity of SnO2.