Multispecies-coadsorption-induced rapid preparation of graphene glass fiber fabric and applications in flexible pressure sensor.

Direct chemical vapor deposition (CVD) growth of graphene on dielectric/insulating materials is a promising strategy for subsequent transfer-free applications of graphene. However, graphene growth on noncatalytic substrates is faced with thorny issues, especially the limited growth rate, which severely hinders mass production and practical applications. Herein, graphene glass fiber fabric (GGFF) is developed by graphene CVD growth on glass fiber fabric. Dichloromethane is applied as a carbon precursor to accelerate graphene growth, which has a low decomposition energy barrier, and more importantly, the produced high-electronegativity Cl radical can enhance adsorption of active carbon species by Cl-CH2 coadsorption and facilitate H detachment from graphene edges. Consequently, the growth rate is increased by ~3 orders of magnitude and carbon utilization by ~960-fold, compared with conventional methane precursor. The advantageous hierarchical conductive configuration of lightweight, flexible GGFF makes it an ultrasensitive pressure sensor for human motion and physiological monitoring, such as pulse and vocal signals.

Overcoming the Incompatibility Between Electrical Conductivity and Electromagnetic Transmissivity: A Graphene Glass Fiber Fabric Design Strategy.

Conventional conductive materials such as metals are crucial functional components of conductive systems in diverse electronic instruments. However, their severe intrinsic impedance mismatch with air dielectric causes strong reflection of incident electromagnetic waves, and the resulting low electromagnetic transmissivity typically interferes with surrounding electromagnetic signal communications in modern multifunction-integrated instruments. Herein, graphene glass fiber fabric (GGFF) that merges intrinsic electrical and electromagnetic properties of graphene with dielectric attributes and highly porous macrostructure of glass fiber fabric (GFF) is innovatively developed. Using a novel decoupling chemical vapor deposition growth strategy, high-quality and layer-limited graphene is prepared on noncatalytic nonmetallic GFF in a controlled manner; this is pivotal to realizing GGFF with the desired compatibility among high conductivity, low electromagnetic reflectivity, and high electromagnetic transmissivity. At the same sheet resistance over a wide range of values (250-3000 Ω·sq-1), the GGFF exhibits significantly lower electromagnetic reflectivity (by 0.42-0.51) and higher transmissivity (by 0.27-0.62) than those of its metal-based conductive counterpart (CuGFF). The material design strategy reported herein provides a constructive solution to eliminate the incompatibility between electrical conductivity and electromagnetic transmissivity faced by conventional conductive materials, spotlighting the applicability of GGFF in electric heating scenarios in radar, antenna, and stealth systems.

Scalable Fabrication of Dual-Function Fabric for Zero-Energy Thermal Environmental Management through Multiband, Synergistic, and Asymmetric Optical Modulations.

Solar heating and radiative cooling techniques have been proposed for passive space thermal management to reduce the global energy burden. However, the currently used single-function envelope/coating materials can only achieve static temperature regulation, presenting limited energy savings and poor adaption to dynamic environments. In this study, a sandwich-structured fabric, composed of vertical graphene, graphene glass fiber fabric, and polyacrylonitrile nanofibers is developed, with heating and cooling functions integrated through multiband, synergistic, (solar spectrum and mid-infrared ranges) and asymmetric optical modulations on two sides of the fabric. The dual-function fabric demonstrates high adaption to the dynamic environment and superior performance in a zero-energy-input temperature regulation. Furthermore, it demonstrates ≈15.5 and ≈31.1 MJ m-2 y-1 higher annual energy savings compared to those of their cooling-only and heating-only counterparts, corresponding to ≈173.7 MT reduction in the global CO2 emission. The fabric exhibits high scalability for batch manufacturing with commercially abundant raw materials and facile technologies, providing a favorable guarantee of its mass production and use.

Graphene Infrared Radiation Management Targeting Photothermal Conversion for Electric-Energy-Free Crude Oil Collection.

Graphene has been widely used as a solar absorber for its broad-band absorption. However, targeting a higher photothermal efficiency, the intrinsic infrared radiation loss of graphene requires to be further reduced. Herein, band structure engineering is performed to modulate graphene infrared radiation. Nitrogen-doped vertical graphene is grown on quartz foam (NVGQF) by the plasma-enhanced chemical vapor deposition method. Under the premise of keeping high solar absorption (250-2500 nm), graphitic nitrogen doping effectively modulates the infrared emissivity (2.5-25 µm) of NVGQF from 0.96 to 0.68, reducing the radiation loss by ∼31%. Based on the excellent photothermal properties of NVGQF, a temperature-gradient-driven crude oil collecting raft is designed, where the crude oil flows along the collecting path driven by the viscosity gradient without any external electric energy input. Compared with a nondoped vertical graphene quartz foam raft, the NVGQF raft with a superior photothermal efficiency shows a significantly enhanced crude oil collecting efficiency by three times. The advances in this work suggest broad radiation-managed application platforms for graphene materials, such as seawater desalination and personal or building thermal management.

Complementary Chemical Vapor Deposition Fabrication for Large-Area Uniform Graphene Glass Fiber Fabric.

The lightweight, flexible, high-performance electrothermal material is in high demand in object thermal management. Graphene glass fiber fabric (GGFF) is characterized by excellent electrical conductivity, light weight, and high flexibility, showing superiorities as an electrothermal material. However, the traditional single-carbon-precursor chemical vapor deposition (CVD) graphene growth strategy commonly suffers from the severe thickness nonuniformity of the large-sized graphene film along the gas-flowing direction. Herein, a complementary CVD graphene growth strategy based on the simultaneous introduction of high- and low-decomposition-energy-barrier mixed carbon precursors is developed. In this way, the large-area uniform GGFF with a dramatically decreased nonuniformity coefficient is fabricated (0.260 in 40 cm × 4 cm). GGFF-based heater presents a widely tunable temperature range (20-170 °C) at low working voltage (<10 V) and uniform large-area heating temperature (171.4 ± 3.6 °C in 20 cm × 15 cm), which realizes remarkable anti/deicing performances under the low energy consumption (fast ice melting rate of 79 s mm-1 under a low energy consumption of 0.066 kWh mm-1 m-2 ). The large-area uniform GGFF possesses substantial advantages for applications in thermal management, and the complementary CVD fabrication strategy shows reliable scalability and universality, which can be extended to the synthesis of various materials.

Flexible Full-Surface Conformal Encapsulation for Each Fiber in Graphene Glass Fiber Fabric against Thermal Oxidation.

Encapsulation for carbon-based electronic devices against oxidation can enhance their long-term working stability. Graphene glass fiber fabric (GGFF), as an advanced flexible electrothermal material, also struggles with graphene oxidation. The flexible, full-surface, conformal encapsulation for each fiber in the large-area fabric puts forward high requirements for encapsulating materials and techniques. Herein, the nanometer-thick h-BN layer was in situ grown on cambered surfaces of each fiber in GGFF with the chemical vapor deposition method. Stable heating duration (500 °C) of h-BN-encapsulated GGFF (h-BN/GGFF) was increased by 1 order of magnitude without compromising the electrothermal performances and flexibility. Theoretical simulations revealed that the enhanced oxidation resistance of h-BN/GGFF was attributed to the decreased interaction and adsorption life of oxygen. The proposed flexible, full-surface, conformal encapsulation technique targeting the fiber-shaped graphene electrothermal device is scalable and can be extended to the other carbon materials, even devices with intricate shapes, which will promote the development of flexible electronics.

Dual-Emitter Graphene Glass Fiber Fabric for Radiant Heating.

Radiant heating, as a significant thermal management technique, is best known for its high thermal effect, media-free operation, good penetration, and compatibility for different heated shapes. To promote sustainable development in this area, developing advanced infrared radiation material is in high demand. In this work, a lightweight, flexible dual-emitter infrared electrothermal material, graphene glass fiber (GGF), is developed by chemical vapor deposition (CVD) method, with both graphene and glass fiber as the radiation elements. Large-area GGF fabric (GGFF) exhibits wavelength-independent high infrared emissivity (0.92) and thermal radiation efficiency (79.4%), as well as ultrafast electrothermal response (190.7 °C s-1 at 9.30 W cm-2) and uniform heating temperature. The superior radiant heating capability of GGFF to traditional alloy heating wires can achieve 33.3% energy saving. GGF can promote the development of efficient and energy-saving heat management technology.

Dependence of Electrical Conductivity on Phase Morphology for Graphene Selectively Located at the Interface of Polypropylene/Polyethylene Composites.

Conductive composites of polypropylene (PP) and polyethylene (PE) filled with thermally reduced graphene oxide (TRG) were prepared using two different processing sequences. One was a one-step processing method in which the TRG was simultaneously melt blended with PE and PP, called TRG/PP/PE. The second was a two-step processing method in which the TRG and the PP were mixed first, and then the (TRG/PP) masterbatch was blended with PE, called (TRG/PP)/PE. The phase morphology and localization of the TRG in TRG/PP/PE and (TRG/PP)/PE composites with different PP/PE compositions were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The TRG was found to be selectively dispersed in the PE phase of the TRG/PP/PE composites, resulting in a low percolation threshold near 2.0 wt%. In the (TRG/PP)/PE composites, the TRG was selectively located at the PP/PE blend interface, resulting in a percolation threshold that was lower than 1.0 wt%. With the addition of 2.0 wt% TRG, the (TRG/PP)/PE composites exhibited a wide range of electrical conductivities at PP/PE weight ratios of 10 w/90 w to 80 w/20 w. Moreover, electrical and rheological measurements of the composites revealed that the co-continuous phase structure is the most efficient candidate for the fabrication of conductive composites.

A 3D-Structured Sustainable Solar-Driven Steam Generator Using Super-Black Nylon Flocking Materials.

Solar-driven evaporation is a promising way of using abundant solar energy for desalinating polluted water or seawater, which addresses the challenge of global fresh water scarcity. Cost-effectiveness and durability are key factors for practical solar-driven evaporation technology. The present cutting-edge techniques mostly rely on costly and complex fabricated nanomaterials, such as metallic nanoparticles, nanotubes, nanoporous hydrogels, graphene, and graphene derivatives. Herein, a black nylon fiber (BNF) flocking board with a vertically aligned array prepared via a convenient electrostatic flocking technique is reported, presenting an extremely high solar absorbance (99.6%), a water self-supply capability, and a unique salt self-dissolution capability for seawater desalination. Through a carefully designed 3D structure, a plug-in-type BNF flocking board steam generator realizes a high evaporation rate of 2.09 kg m-2 h-1 under 1 kW m-2 solar illumination, well beyond its corresponding upper limit of 1.50 kg m-2 h-1 (assuming 100% solar energy is being used for evaporation latent heat). With the advantages of high-efficiency fabrication, cost-effectiveness, high evaporation rate, and high endurance in seawater desalination, this 3D design provides a new strategy to build up an economic, sustainable, and rapid solar-driven steam generation system.