Prolifera‐Green‐Tide as Sustainable Source for Carbonaceous Aerogels with Hierarchical Pore to Achieve Multiple Energy Storage

The increasing demand for efficient energy storage and conversion devices has aroused great interest in designing advanced materials with high specific surface areas, multiple holes, and good conductivity. Here, we report a new method for fabricating a hierarchical porous carbonaceous aerogel (HPCA) from renewable seaweed aerogel. The HPCA possesses high specific surface area of 2200 m² g^?1 and multilevel micro/meso/macropore structures. These important features make HPCA exhibit a reversible lithium storage capacity of 827.1 mAh g^?1 at the current density of 0.1 A g^?1, which is the highest capacity for all the previously reported nonheteroatom‐doped carbon nanomaterials. It also shows high specific capacitance and excellent rate performance for electric double layer capacitors (260.6 F g^?1 at 1 A g^?1 and 190.0 F g^?1 at 50 A g^?1), and long cycle life with 91.7% capacitance retention after 10 000 cycles at 10 A g^?1. The HPCA also can be used as support to assemble Co₃O₄ nanowires (Co₃O₄@HPCA) for constructing a high performance pseudocapacitor with the maximum specific capacitance of 1167.6 F g^?1 at the current density of 1 A g^?1. The present work highlights the first example in using prolifera‐green‐tide as a sustainable source for developing advanced carbon porous aerogels to achieve multiple energy storage.     

Nitrogen‐Enriched Nonporous Carbon Electrodes with Extraordinary Supercapacitance

Nitrogen‐enriched nonporous carbon materials derived from melamine–mica composites are subjected to ammonia treatment to further increase the nitrogen content. For samples preoxidized prior to the ammonia treatment, the nitrogen content is doubled and is mainly incorporated in pyrrol‐like groups. The materials are tested as electrodes for supercapacitors, and in acidic or basic electrolytes, the gravimetric capacitance of treated samples is three times higher than that of untreated samples. This represents a tenfold increase of the capacitance per surface area (3300 µF cm^?2) in basic electrolyte. Due to the small volume of the carbon materials, high volumetric capacitances are achieved in various electrolytic systems: 280 F cm^?3 in KOH, 152 F cm^?3 in H₂SO₄, and 92 F cm^?3 in tetraethylammonium tetrafluoroborate/propylene carbonate.     

Effects of Growth Temperature and Annealing on Properties of Zn3Sn2O7 Thin Films and Application in TFTs

The effects of growth temperature and annealing on the physical properties of Zn₃Sn₂O₇ thin films were investigated in this work. The Zn₃Sn₂O₇ thin films were deposited on glass substrates by radio frequency (rf) magnetron sputtering. It is found that the films are amorphous regardless of the growth temperature. The film grown at room temperature shows the highest mobility of 8.1 cm² V^?1 s^?1 and the lowest carrier concentration of 2.0 × 10¹⁵ cm^?3. The highest carrier concentration of 1.6 × 10¹⁹ cm^?3 is obtained at the growth temperature of 250°C. Annealing treatment of the Zn₃Sn₂O₇ thin films resulted in increases of carrier concentration and mobility. The average transmittance of the as-deposited and annealed films reaches 80%. By using a Zn₃Sn₂O₇ thin film as the channel and a Ta₂O₅ thin film as the insulating layer, we fabricated transparent Zn₃Sn₂O₇ thin-film transistors with field-effect mobility of 21.2 cm² V^?1 s^?1, on/off current ratio of 10⁵, threshold voltage of 0.8 V, and subthreshold swing of 0.8 V/decade.     

Direct Ink Writing of Adjustable Electrochemical Energy Storage Device with High Gravimetric Energy Densities

3D printing graphene aerogel with periodic microlattices has great prospects for various practical applications due to their low density, large surface area, high porosity, excellent electrical conductivity, good elasticity, and designed lattice structures. However, the low specific capacitance limits their development in energy storage fields due to the stacking of graphene. Therefore, constructing a graphene‐based 2D materials hybridization aerogel that consists of the pseduocapacitive substance and graphene material is necessary for enhancing electrochemical performance. Herein, 3D printing periodic graphene‐based composite hybrid aerogel microlattices (HAMs) are reported via 3D printing direct ink writing technology. The rich porous structure, high electrical conductivity, and highly interconnected networks of the HAMs aid electron and ion transport, further enabling excellent capacitive performance for supercapacitors. An asymmetric supercapacitor device is assembled by two different 4‐mm‐thick electrodes, which can yield high gravimetric specific capacitance (C_g) of 149.71 F g^?1 at a current density of 0.5 A g^?1 and gravimetric energy density (E_g) of 52.64 Wh kg^?1, and retains a capacitance retention of 95.5% after 10 000 cycles. This work provides a general strategy for designing the graphene‐based mixed‐dimensional hybrid architectures, which can be utilized in energy storage fields.     

Transport Properties of CuInTe<Subscript>2</Subscript> Thin Films Obtained by the Electrochemical Route

CuInTe₂ (CIT) thin films were potentiostatically electrodeposited onto cadmium sulfide thin films coated on fluorine doped tin oxide (FTO) glass in an aqueous bath at 75°C by the standard three-electrode system at ??0.7 V and ??0.8 V, with respect to an Ag/AgCl reference electrode. The electrodeposited layers were heat treated at?～?80°C in air ambient for 60 min. X-ray diffraction pattern and Raman analysis confirmed the formation of chalcopyrite CIT thin films upon heat treatment. The optical band gap of heat treated CIT films was found to be?～?1.0 eV and 0.95 eV deposited at ??0.7 V and ??0.8 V, respectively. Compact and good adhesive growth of CIT layers onto CdS coated FTO substrates is confirmed by field emission scanning electron microscopy. The current density–voltage (J–V) and capacitance–voltage (C–V) measurement was studied to understand the electronic quality of material for development of CIT layers for solar cell applications. The current density was found to be increased by two orders of magnitude upon low-temperature heat treatment. The capacitance–voltage measurement showed sharp depletion and accumulation region. The built in potential was found to be ～?60 mV and 145 mV in the as-deposited samples, deposited at ??0.7 V and ??0.8 V, respectively, whereas upon heat treatment it shifted to 159 mV and 210 mV. The capacitance of the CIT films was found to be a function of applied bias and increased with increasing the bias voltage. The depletion width of the heat treated sample was found to be?～?20 nm and 200 nm for the sample deposited at ??0.7 V and ??0.8 V, respectively. Thus, the sample deposited at ??0.8 V shows optimum electronic properties and is found to be suitable for opto-electronic applications.     

Multifunctional Carbon for Electrochemical Double‐Layer Capacitors

Multifunctional carbon materials are prepared for application as an active electrode material in an electrochemical capacitor displaying both charge storage and binder properties. The synthesis of the materials involves the functionalization of high surface area Black Pearls 2000 carbon black by a covalent attachment of polyacrylic acid. The polyacrylic acid polymer is formed by atom transfer radical polymerization using 1‐(bromoethyl)benzene groups initially bonded to the carbon by spontaneous grafting from the corresponding diazonium ions. The grafting of 1‐(bromoethyl)benzene and polyacrylic acid is confirmed by thermogravimetric analysis, Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, and nitrogen gas adsorption isotherm. The composite electrode films prepared from the modified carbon are more hydrophilic and have better wettability in an aqueous electrolyte than the one prepared with the unmodified carbon. The modified electrodes also show a higher specific capacitance (≈140 F g^?1), a wider working potential window (1.5 V) and excellent specific capacitance retention upon cycling (99.9% after 5000 cycles) in an aqueous 0.65 m K₂SO₄ electrolyte. Moreover, a relatively high specific capacitance (≈90 F g^?1) is maintained at a scan rate of 1000 mV s^?1 with the polyacrylic‐acid‐modified carbon electrode.     

Self-Supported Ni<Subscript>0.85</Subscript>Se Nanosheets Array on Carbon Fiber Cloth for a High-Performance Asymmetric Supercapacitor

In this work, Ni_0.85Se nanosheets array electrode material was prepared with carbon fiber cloth (CFC) as a substrate. Owing to their special structure, the Ni_0.85Se nanosheets array exhibits an outstanding energy storage property with a superior specific capacitance (820 F/g) and great rate capability (83.17%). Moreover, the Ni_0.85Se electrode presents an great cycling performance with 82.63% retention after 10,000 cycles. The asymmetric supercapacitor (ASC) was fabricated based on Ni_0.85Se positive and activated carbon (AC) negative electrode materials, with KOH/PVA gel as the electrolyte, respectively. A highest energy density of 29 W h kg^?1 was achieved at a power density of 779 W kg^?1 under the optimal potential range of 1.6 V. Furthermore, the Ni_0.85Se//AC ASC devices demonstrate a great cycling performance of 81.25% capacitance retention after 5000 charge–discharge cycles. These excellent performance provide strong evidence to confirm the conclusion that Ni_0.85Se nanosheets array used as electrode materials in supercapacitors and Ni_0.85Se//AC asymmetric supercapacitors hold significant potential in the field of energy storage.     

Development of 3.7 % Efficient Cu2ZnSnSe4 Solar Cells by Selenizing Cu-Zn-Sn Films Deposited by DC Sputtering on TiN-Protected Mo/Glass Substrates

Cu₂ZnSnSe₄ (CZTSe) films for solar cell devices were fabricated by sputtering of a Cu-Zn-Sn target followed by post-selenization at 500–600 °C for 1 h in the presence of single or double compensation discs to supply Se vapor. The optimized selenization conditions avoided the Se deficiency and enhanced the grain growth of CZTSe films. The 600 °C-selenized CZTSe films adjacent with double discs obtained the large grains of 2–5 μm and had a [Cu]/([Zn]+[Sn]) ratio of 0.94 and a [Zn]/[Sn] ratio of 1.34. In order to fabricate the device on Mo-coated glass substrates, a TiN reaction barrier layer was coated before the Cu-Zn-Sn sputtering coating. The TiN-CZTSe device had 3.7 % efficiency (η), as compared to 0.58 % for the TiN-free one. The efficient device had the CZTSe layer with hole concentration (n _p) of 3.4 × 10¹⁷ cm^?3, Hall mobility (μ) of 54 cm² V^?1 s^?1, and electrical conductivity (σ) of 2.9 Ω^?1 cm^?1.     

Enhancing the Thermoelectric Properties of Ca3Co4O9 Thin Films by the Addition of a Nanoscale NbN x Second Phase

High-quality Ca₃Co₄O₉ (CCO) thin films have been epitaxially grown on c-cut Al₂O₃ single crystal substrates using pulsed laser deposition (PLD). Different doses of Nb ions were injected into the films using an ion beam injection technique, and a nanoscale NbN _x second phase was generated in the films after annealing in pure N₂. The resistivity and Seebeck coefficient of the films were measured in the temperature range 175–375 K. The results demonstrated that the power factor of the films increases when injected with appropriate quantities of Nb. When the injected Nb concentration was 1.46 × 10²⁰/cm³, the power factor of the film reached 0.17 mW/m K² at room temperature, which is nearly twice as large as that for pure CCO film. A maximum value of 0.22 mW/m K² was obtained at 375 K.     

Effect of thermal annealing and exposure to oxygen plasma on the properties of TiO2-Si structures

The effect of thermal annealing and exposure to oxygen plasma on the phase composition, structure, and microprofile of titanium-dioxide films deposited by high-frequency magnetron sputtering on silicon substrates is studied. The influence exerted by processing modes on the capacitance-voltage and conductance-voltage characteristics of Me-TiO₂-Si-Me structures and on the density of surface states at the semiconductor-insulator interface is examined. It is shown that TiO₂ films are amorphous upon their fabrication. Upon the annealing of films at 500°C in an argon atmosphere, crystallites of anatase and rutile appear in the amorphous matrix. The treatment of a titanium-dioxide film in oxygen plasma gives rise to rutile crystallites with new crystallographic planes. As a result of annealing at 750°C, the anatase phase disappears and the film becomes polycrystalline, containing only rutile crystallites. The capacitance of Me-TiO₂-Si-Me structures in the accumulation mode reaches the maximum value upon annealing at 750°C, which is due to the transformation of titanium dioxide to the rutile phase. The specific capacitance is 5.9 × 10^?2 F/cm³. The decrease in the capacitance of the structures and in the amount of fixed charge in the insulator upon exposure to oxygen plasma is due to the diffusion of oxygen atoms across the titanium-dioxide layer to give a SiO₂ film at the TiO₂-Si interface. As a result of the annealing and treatment of a titanium-dioxide film in oxygen plasma, the energy density of surface states decreases by more than an order of magnitude as compared with the unannealed samples.     

Thermopower Enhancement of Bi2Te3 Films by Doping I Ions

The thermoelectric properties of I-doped Bi₂Te₃ films grown by metal-organic chemical vapor deposition have been studied. I-doped epitaxial (00l) Bi₂Te₃ films were successfully grown on 4° tilted GaAs (001) substrates at 360 °C. I concentration in the Bi₂Te₃ films was easily controlled by the variation in a flow rate of H₂ carrier gas for the delivery of an isopropyliodide precursor. As I ions in the as-grown Bi₂Te₃ films were not fully activated, they did not influence the carrier concentration and thermoelectric properties. However, a post-annealing process at 400 °C activated I ions as a donor, accompanied with an increase in the carrier concentration. Interestingly, the I-doped Bi₂Te₃ films after the post-annealing process also exhibited enhancement of the Seebeck coefficient at the same electron concentration compared to un-doped Bi₂Te₃ films. Through doping I ions into Bi₂Te₃, the thermopower was also enhanced in Bi₂Te₃, and a high power factor of 5 × 10^?3 W K^?2 m^?1 was achieved.     

Ultra‐High Surface Area Nitrogen‐Doped Carbon Aerogels Derived From a Schiff‐Base Porous Organic Polymer Aerogel for CO2 Storage and Supercapacitors

Nitrogen‐doped carbon aerogels (NCAs) have received great attention for a wide range of applications, from thermal electronics to waste water purification, heavy metal or gas adsorption, energy storage, and catalyst supports. Herein NCAs are developed via the synthesis of a Schiff‐base porous organic polymer aerogel followed by pyrolysis. By controlling the pyrolysis temperature, the polymer aerogel can be simply converted into porous NCAs with a low bulk density (5 mg cm^?3), high surface area (2356 m² g^?1), and high bulk porosity (70%). The NCAs containing 1.8–5.3 wt% N atoms exhibit remarkable CO₂ uptake capacities (6.1 mmol g^?1 at 273 K and 1 bar, 33.1 mmol g^?1 at 323 K and 30 bar) and high ideal adsorption solution theory selectivity (47.8) at ambient pressure. Supercapacitors fabricated with NCAs display high specific capacitance (300 F g^?1 at 0.5 A g^?1), fast rate (charge to 221 F g^?1 within only 17 s), and high stability (retained >98% capacity after 5000 cycles). Asymmetric supercapacitors assembled with NCAs also show high energy density and power density with maximal values of 30.5 Wh kg^?1 and 7088 W kg^?1, respectively. The outstanding CO₂ uptake and energy storage abilities are attributed to the ultra‐high surface area, N‐doping, conductivity, and rigidity of NCA frameworks.     

High Surface Area MoS2/Graphene Hybrid Aerogel for Ultrasensitive NO2 Detection

A MoS₂/graphene hybrid aerogel synthesized with two‐dimensional MoS₂ sheets coating a high surface area graphene aerogel scaffold is characterized and used for ultrasensitive NO₂ detection. The combination of graphene and MoS₂ leads to improved sensing properties with the graphene scaffold providing high specific surface area and high electrical and thermal conductivity and the single to few‐layer MoS₂ sheets providing high sensitivity and selectivity to NO₂. The hybrid aerogel is integrated onto a low‐power microheater platform to probe the gas sensing performance. At room temperature, the sensor exhibits an ultralow detection limit of 50 ppb NO₂. By heating the material to 200 °C, the response and recovery times to reach 90% of the final signal decrease to <1 min, while retaining the low detection limit. The MoS₂/graphene hybrid also shows good selectivity for NO₂ against H₂ and CO, especially when compared to bare graphene aerogel. The unique structure of the hybrid aerogel is responsible for the ultrasensitive, selective, and fast NO₂ sensing. The improved sensing performance of this hybrid aerogel also suggests the possibility of other 2D material combinations for further sensing applications.     

Characterization of n-Type and p-Type ZnS Thin Layers Grown by an Electrochemical Method

Electrodeposition of n-type and p-type thin-film layers of ZnS was carried out using a simple two-electrode system and aqueous solutions of ZnCl₂ and (NH₄)₂S₂O₃ with different Zn²⁺ concentrations. X-ray diffraction measurements show that the ZnS layers deposited from both solutions are amorphous. Optical absorption measurements show low absorbance of the layers with energy bandgap in the range of 3.68 eV to 3.78 eV after postdeposition annealing. Photoelectrochemical cell measurements show that both n-type and p-type ZnS thin layers can be electrodeposited by simply changing the concentrations of the deposition solutions. With higher Zn²⁺ concentration in the bath, n-type ZnS films were deposited, while p-type ZnS films were deposited with lower Zn²⁺ concentration. The estimated resistivity of layers from both solutions using I–V measurements were 3.0 × 10⁴ Ω cm and 2.0 × 10⁴ Ω cm, respectively, for n-ZnS and p-ZnS. Scanning electron microscopy shows that the deposited films consist of particles with good surface coverage of the glass/fluorine-doped tin oxide substrate.     

High Pseudocapacitance from Ultrathin V2O5 Films Electrodeposited on Self‐Standing Carbon‐Nanofiber Paper

An ultrathin V₂O₅ layer was electrodeposited by cyclic voltammetry on a self‐standing carbon‐nanofiber paper, which was obtained by stabilization and heat‐treatment of an electrospun polyacrylonitrile (PAN)‐based nanofiber paper. A very‐high capacitance of 1308 F g^?1 was obtained in a 2 M KCl electrolyte when the contribution from the 3 nm thick vanadium oxide was considered alone, contributing to over 90% of the total capacitance (214 F g^?1) despite the low weight percentage of the V₂O₅ (15 wt%). The high capacitance of the V₂O₅ is attributed to the large external surface area of the carbon nanofibers and the maximum number of active sites for the redox reaction of the ultrathin V₂O₅ layer. This ultrathin layer is almost completely accessible to the electrolyte and thus results in maximum utilization of the oxide (i.e., minimization of dead volume). This hypothesis was experimentally evaluated by testing V₂O₅ layers of different thicknesses.     

One‐Step Electrochemical Synthesis of Graphene/Polyaniline Composite Film and Its Applications

This work describes a new one‐step large‐scale electrochemical synthesis of graphene/polyaniline (PANI) composite films using graphite oxide (GO) and aniline as the starting materials. The size of the film could be controlled by the area of indium tin oxide (ITO). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible absorption spectrum (UV–vis) results demonstrated that the graphene/PANI composite film was successfully synthesized. The obtained graphene/PANI composite film showed large specific area, high conductivity, good biocompatibility, and fast redox properties and had perfect layered and encapsulated structures. Electrochemical experiments indicated that the composite film had high performances and could be widely used in applied electrochemical fields. As a model, horseradish peroxidase (HRP) was entrapped onto the film‐modi?ed glassy carbon electrode (GCE) and used to construct a biosensor. The immobilized HRP showed a pair of well‐de?ned redox peaks and high catalytic activity for the reduction of H₂O₂. Furthermore, the graphene/PANI composite film could be directly used as the supercapacitor electrode. The supercapacitor showed a high specific capacitance of 640 F g^?1 with a retention life of 90% after 1000 charge/discharge cycles.     

Bi2SiO5 Doping Concentration Effects on the Electrical Properties of SrBi2Ta2O9 Films

In this paper, we investigated the microstructure and electrical properties of Bi₂SiO₅ (BSO) doped SrBi₂Ta₂O₉ (SBT) films deposited by chemical solution deposition. X-ray diffraction observation indicated that the crystalline structures of all the BSO-doped SBT films are nearly the same as those of a pure SBT film. Through BSO doping, the 2Pr and 2Ec values of SBT films were changed from 15.3 μC/cm² and 138 kV/cm of pure SBT to 1.45 μC/cm² and 74 kV/cm of 10 wt.% BSO-doped SBT. The dielectric constant at 1 MHz for SBT varied from 199 of pure SBT to 96 of 10 wt.% BSO-doped SBT. The doped SBT films exhibited higher leakage current than that of non-doped SBT films. Nevertheless, all the doped SBT films still had small dielectric loss and low leakage current. Our present work will provide useful insights into the BSO doping effects to the SBT films, and it will be helpful for the material design in the future nonvolatile ferroelectric memories.     

Effects of nitrogen trifluoride on the growth and properties of plasma-enhanced chemical-vapor-deposited diamond-like carbon films

The effects of nitrogen trifluoride (NF₃) on the growth and properties of plasma-enhanced chemical-vapor-deposited diamond-like carbon (DLC) films were investigated. The addition of NF₃ increases the deposition rate of DLC film due presumably to the removal of activated hydrogen species by the fluorine radical (F⁻). Diamond-like carbon films deposited in a methane/NF₃ mixture have a higher refractive index, a lower bulk resistivity, and a lower optical bandgap compared to films deposited in pure methane due to a lower hydrogen content in the films. Moreover, the bulk resistivity of methane/NF₃ DLC films remains constant for annealing temperatures below 400°C. Thus, DLC films deposited with NF₃ are more stable than DLC films deposited without NF₃.     

Effects of excess Bi concentration, buffered Bi2O3 layer, and Ta doping on the orientation and ferroelectricity of chemical-solution-deposited Bi3.25La0.75Ti3O12 films

Effects of excess Bi concentration, buffered Bi₂O₃ layer, and Ta doping on the orientation and ferroelectricity of chemical-solution-deposited (CSD) Bi_3.25La_0.75Ti₃O₁₂ (BLT) films on Pt/SiO₂/Si(100) were studied. The optimum concentration of excess Bi added to the BLT films to achieve a larger remanent polarization (2Pr) was 10 mol.%. The buffered Bi₂O₃ layers could reduce the temperature for c-axis-oriented growth of BLT films from 850°C to 700°C. However, two-step annealing, i.e., first annealed at 650°C and then annealed at a temperature of 700–850°C, could effectively suppress the c-axis-oriented growth and thus improve the 2Pr of BLT films. The improvement of the 2Pr of BLT films can be explained in terms of the large polarization along the a-axis orientation and buffered Bi₂O₃ layers, which compensate the BLT films for Bi evaporation during annealing. The Ta doping can induce two contrary effects on the 2Pr of BLT films. For the (Bi_3.25La_0.75)(Ti_3−xTa_x)O₁₂ (BLTTx) films with x=0.005, the effect of a decrease of oxygen vacancies would be dominant, resulting in the improvement of 2Pr. Because the Ta concentration (x) in the BLTTx films exceeds 0.01, the effect of a decrease of grain size would become dominant, resulting in the degradation of 2Pr.     

Sequential Evaporation of Bi-Te Thin Films with Controllable Composition and Their Thermoelectric Transport Properties

We report a simplified sequential evaporation route that can deposit compositionally controllable Bi-Te thermoelectric (TE) thin films without the need for a highly controlled facility. Te and Bi granules were used as starting materials, with their ratio being adjusted to obtain Bi-Te films with different compositions and thicknesses. The as-evaporated and annealed films were subjected to structural and morphological analysis, and their transport properties were measured. X-Ray diffraction data revealed multiple phases for most films. Energy-dispersive x-ray spectroscopy showed that the film composition was Te-enriched due to the large vapor pressure difference of Te and Bi. A Bi₂Te₃ single phase was obtained in the annealed films, having nominal composition of BiTe_1.2. The existence of impurity phases, such as Bi₄Te₃ or elemental Te, was found in all the as-evaporated films and in the annealed films with other nominal Te/Bi ratios, which degraded the TE properties of the films by increasing their electrical conductivity and reducing their Seebeck coefficient. A pure Bi₂Te₃ film with nominal Te/Bi ratio of 1.2 exhibited a maximum power factor of 7.9 × 10^?4 W m^?1 K² after annealing at 200°C. This work demonstrated a simple, undemanding, reliable method to deposit Bi-Te-based TE thin films that can be utilized to fabricate low-cost TE microgenerators.