Showing papers on "FOIL method published in 2018"

Metal ion cycling of Cu foil for selective C–C coupling in electrochemical CO2 reduction

Abstract: Electrocatalytic CO2 reduction to higher-value hydrocarbons beyond C1 products is desirable for applications in energy storage, transportation and the chemical industry. Cu catalysts have shown the potential to catalyse C–C coupling for C2+ products, but still suffer from low selectivity in water. Here, we use density functional theory to determine the energetics of the initial C–C coupling steps on different Cu facets in CO2 reduction, and suggest that the Cu(100) and stepped (211) facets favour C2+ product formation over Cu(111). To demonstrate this, we report the tuning of facet exposure on Cu foil through the metal ion battery cycling method. Compared with the polished Cu foil, our 100-cycled Cu nanocube catalyst with exposed (100) facets presents a sixfold improvement in C2+ to C1 product ratio, with a highest C2+ Faradaic efficiency of over 60% and H2 below 20%, and a corresponding C2+ current of more than 40 mA cm–2. Electrocatalytic reduction of CO2 to products containing multiple carbon atoms is useful for producing high-value chemicals and fuels. This work uses theory to predict the preferred copper surface for C–C coupling, and subsequent metal ion cycling to produce the desired facets results in a catalyst that is highly selective for C2+ products.

Robust Pinhole-free Li3N Solid Electrolyte Grown from Molten Lithium.

Abstract: Lithium metal is the ultimate anode choice for high energy density rechargeable lithium batteries. However, it suffers from inferior electrochemical performance and safety issues due to its high reactivity and the growth of lithium dendrites. It has long been desired to develop a materials coating on Li metal, which is pinhole-free, mechanically robust without fracture during Li metal deposition and stripping, and chemically stable against Li metal and liquid electrolytes, all while maintaining adequate ionic conductivity. However, such an ideal material coating has yet to be found. Here we report a novel synthesis method by reacting clean molten lithium foil directly with pure nitrogen gas to generate instantaneously a pinhole-free and ionically conductive α-Li3N film directly bonded onto Li metal foil. The film consists of highly textured large Li3N grains (tens of μm) with (001) crystalline planes parallel to the Li metal surface. The bonding between textured grains is strong, resulting in a mechanical...

Highly Oriented Monolayer Graphene Grown on a Cu/Ni(111) Alloy Foil

Abstract: Fast-growth of single crystal monolayer graphene by CVD using methane and hydrogen has been achieved on “homemade” single crystal Cu/Ni(111) alloy foils over large area. Full coverage was achieved in 5 min or less for a particular range of composition (1.3 at.% to 8.6 at.% Ni), as compared to 60 min for a pure Cu(111) foil under identical growth conditions. These are the bulk atomic percentages of Ni, as a superstructure at the surface of these foils with stoichiometry Cu6Ni1 (for 1.3 to 7.8 bulk at.% Ni in the Cu/Ni(111) foil) was discovered by low energy electron diffraction (LEED). Complete large area monolayer graphene films are either single crystal or close to single crystal, and include folded regions that are essentially parallel and that were likely wrinkles that “fell over” to bind to the surface; these folds are separated by large, wrinkle-free regions. The folds occur due to the buildup of interfacial compressive stress (and its release) during cooling of the foils from 1075 °C to room tempera...

High-Performance Carbon Nanotube Complementary Electronics and Integrated Sensor Systems on Ultrathin Plastic Foil.

Abstract: The longtime vacancy of high-performance complementary metal-oxide-semiconductor (CMOS) technology on plastics is a non-negligible obstacle to the applications of flexible electronics with advanced functions, such as continuous health monitoring with in situ signal processing and wireless communication capabilities, in which high speed, low power consumption, and complex functionality are desired for integrated circuits (ICs). Here, we report the implementation of carbon nanotube (CNT)-based high-performance CMOS technology and its application for signal processing in an integrated sensor system for human body monitoring on ultrathin plastic foil with a thickness of 2.5 μm. The performances of both the p- and n-type CNT field-effect transistors (FETs) are excellent and symmetric on plastic foil with a low operation voltage of 2 V: width-normalized transconductances (gm/W) as high as 4.69 μS/μm and 5.45 μS/μm, width-normalized on-state currents reaching 5.85 μA/μm and 6.05 μA/μm, and mobilities up to 80.26...

Dry transfer of graphene to dielectrics and flexible substrates using polyimide as a transparent and stable intermediate layer

Abstract: We demonstrate the direct transfer of graphene from Cu foil to rigid and flexible substrates, such as glass and PET, using as an intermediate layer a thin film of polyimide (PI) mixed with an aminosilane (3-aminopropyltrimethoxysilane) or only PI, respectively. While the dry removal of graphene by an adhesive has been previously demonstrated—being removed from graphite by scotch tape or from a Cu foil by thick epoxy (~20 µm) on Si—our work is the first step towards making a substrate ready for device fabrication using the polymer-free technique. Our approach leads to an article that is transparent, thermally stable—up to 350 °C—and free of polymer residues on the device side of the graphene, which is contrary to the case of the standard wet-transfer process using PMMA. Also, in addition to previous novelty, our technique is fast and easier by using current industrial technology—a hot press and a laminator—with Cu recycling by its mechanical peel-off; it provides high interfacial stability in aqueous media and it is not restricted to a specific material—polyimide and polyamic acids can be used. All the previous reasons demonstrate a feasible process that enables device fabrication.

A resistive switching memory device with a negative differential resistance at room temperature

Abstract: In this study, large-area ZnO nanorod arrays covering a Zn foil substrate were produced by a low-cost and low temperature approach. In this approach, oxidation of zinc metal was achieved in a formamide/water mixture. Taking advantage of the product, a sandwiched structure, Ag/ZnO/Zn, was fabricated in which Ag acts as the top electrode, ZnO as the active layer and Zn foil as the bottom electrode. Resistive switching memory behavior (with an HRS/LRS resistance ratio of ∼10) along with a negative differential resistance effect (the largest slope being −3.85) was synchronously observed for this device at room temperature. This device opens up possibilities for multifunctional components in future electronic applications.

Fabrication, characterization and photoelectrochemical properties of cuprous oxide-reduced graphene oxide photocatalysts for hydrogen generation

Abstract: Reduced graphene oxide protected Cu2O/Cu foil (rGO/Cu2O/Cu foil) photocathodes have been synthesized via a two-step strategy. (NH4)2S2O8 was first used to oxidize Cu foil and prepare Cu(OH)2 nanostructures/Cu foil. In the second step, graphene oxide (GO) solution and the prepared Cu(OH)2/Cu foil sample were hydrothermally reacted in a Teflon lined stainless steel autoclave for different periods of time at 120 °C, followed by calcination at 450 °C under N2 atmosphere for 3 h. The effect of modification of rGO on the photoelectrochemical activity of different rGO/Cu2O/Cu foil samples has been studied by FESEM, XRD, FTIR, Raman spectroscopy and UV–Vis diffuse reflectance spectroscopy. Continuous and transparent layer of GO sheets are formed on the surface of Cu(OH)2 nanostructures/Cu foil, according to FESEM results. The photoelectrochemical properties of the prepared samples in the dark and under illumination conditions were investigated using linear sweep voltammetry and chronoamperometry techniques. The rGO/Cu2O/Cu foil photocathodes exhibit enhanced photocurrent density under illumination (85 mW/cm2) in comparison with the bare Cu2O/Cu foil photocathode. The improved separation efficiency of photogenerated charge carriers may be mainly accounted for this enhanced photoelectrochemical performance. A low photostability of 12.5% of the initial photocurrent density was observed for the bare Cu2O/Cu foil photocathode after 1000s of illumination whereas this value reached to almost 77% after modification of rGO. The new rGO/Cu2O/Cu foil nanocomposite prepared in this study is believed to be a promising photocathode material in photoelectrochemical cells for efficient water splitting.

Hierarchically Mesostructured Aluminum Current Collector for Enhancing the Performance of Supercapacitors.

Abstract: Aluminum (Al) current collector is one of the most important components of supercapacitors, and its performance has vital effects on the electrochemical performance and cyclic stability of supercapacitors. In the present work, a scalable and low-cost, yet highly efficient, picosecond laser processing method of Al current collectors was developed to improve the overall performance of supercapacitors. The laser treatment resulted in hierarchical micro-nanostructures on the surface of the commercial Al foil and reduced the surface oxygen content of the foil. The electrochemical performance of the Al foil with the micro-nanosurface structures was examined in the symmetrical activated carbon-based coin supercapacitors with an organic electrolyte. The results suggest that the laser-treated Al foil (laser-Al) increased the capacitance density of supercapacitors up to 110.1 F g-1 and promoted the rate capability due to its low contact resistance with the carbonaceous electrode and high electrical conductivity derived from its larger specific surface areas and deoxidized surface. In addition, the capacitor with the laser-Al current collector exhibited high cyclic stability with 91.5% capacitance retention after 10 000 cycles, 21.3% higher than that with pristine-Al current collector due to its stronger bonding with the carbonaceous electrode that prevented any delamination during aging. Our work has provided a new strategy for improving the electrochemical performance of supercapacitors.

Chromatic Titanium Photoanode for Dye-Sensitized Solar Cells under Rear Illumination

Abstract: Titanium (Ti) has high potential in many practical applications such as biomedicine, architecture, aviation, and energy. In this study, we demonstrate an innovative application of dye-sensitized solar cells (DSSCs) based on Ti photoanodes that can be integrated into the roof engineering of large-scale architectures. A chromatic Ti foil produced by anodizing oxidation (coloring) technology is an attractive roof material for large-scale architecture, showing a colorful appearance due to the formation of a reflective TiO2 thin layer on both surfaces of Ti. The DSSC is fabricated on the backside of the chromatic Ti foil using the Ti foil as the working electrode, and this roof-DSSC hybrid configuration can be designed as an energy harvesting device for indoor artificial lighting. Our results show that the facet-textured TiO2 layer on the chromatic Ti foil not only improves the optical reflectance for better light utilization but also effectively suppresses the charge recombination for better electron collection. The power conversion efficiency of the roof-DSSC hybrid system is improved by 30-40% with a main contribution from an improvement of short-circuit current density under standard 1 sun and dim-light (600-1000 lx) illumination.

One-Step Fast-Synthesized Foamlike Amorphous Co(OH)2 Flexible Film on Ti Foil by Plasma-Assisted Electrolytic Deposition as a Binder-Free Anode of a High-Capacity Lithium-Ion Battery.

Abstract: This research prepared an amorphous Co(OH)2 flexible film on Ti foil using plasma-assisted electrolytic deposition within 3.5 min. Amorphous Co(OH)2 structure was determined by X-ray diffraction and X-ray photoelectron spectroscopy. Its areal capacity testing as the binder and adhesive-free anode of a lithium-ion battery shows that the cycling capacity can reach 2000 μAh/cm2 and remain at 930 μAh/cm2 after 50 charge-discharge cycles, which benefits from the emerging Co(OH)2 active material and amorphous foamlike structure. The research introduced a new method to synthesize amorphous Co(OH)2 as the anode in a fast-manufactured low-cost lithium-ion battery.

An experimental investigation on heat transfer enhancement in circular jet impingement on hot surfaces by using Al2O3/water nano-fluids and aqueous high-alcohol surfactant solution

Abstract: The present article reports the heat transfer characteristics of a vertical stainless steel foil of 0.15 mm thickness (SS304) by circular impinging jets of various fluids such as pure water, nano-f...

Palladium-Based Hydrogen Sensors Using Fiber Bragg Gratings

Abstract: This paper reports on the development and evaluation of fiber optic hydrogen sensors based on fiber Bragg gratings. The sensors were tested in a newly developed measurement system for long term experiments of fiber optic gas sensors. Two types of palladium metal sensors were manufactured; sputter coated and a new concept using palladium foil. The sputter coated sensor has a 1600 nm palladium coating with a 30 nm titanium layer between the etched fiber and the palladium serving as an adhesion layer. The foil sensors have either a 20 μ m or 100 μ m palladium foil attached to the fiber. The sensors were tested for different hydrogen concentration in a newly developed gas sensing test setup. The maximum wavelength change (at 90 °C and 1060 mbar with both 1% and 5% hydrogen in nitrogen) of the coated sensor, the 20 μ m and the 100 μ m foil sensor was found to be 10, 160, and 80 pm respectively to 1% hydrogen and 25, 480, and 225 pm respectively to 5% hydrogen. A method is presented for calculating the wavelength change of the coated and foil sensors to show the current limitations and the theoretical future potential of each sensor.