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The 2D single crystal WO3 nanosheets with (101) preferred orientation facets self-assembled on an FTO substrate and were applied to an aqueous electrochromic-supercapacitor.

Electrochromic devices (ECDs) can regulate the indoor solar radiation by adjusting optical transmissive properties, showing great commercial potential and important social value of green energy saving. However, the unsafety and high cost of Li+ based electrolyte hinder the large-scale and industrialized production of ECDs. Other metal ions have been used as electrolyte ions, but they are rarely reported in all solid state ECDs. In this study, MgF2 film is used as the solid electrolyte to construct all solid state ECD with the structure of glass/ITO/WO3/MgF2/NiO/ITO. The ECD shows the large optical modulation (∼83% at 820 nm, with 100 s durations) and fast response (19.2 s for bleaching and 8.3 s for coloring, with 25 s durations). Moreover, the ECD achieves the extreme transmittance value of colored states Tc ≈ 0%, which can give an absolute private state. This work not only indicates that MgF2 film can be an alternative to Li+ based electrolyte in all solid state ECDs, but also broadens the applications of all solid state EC smart windows to private buildings.

Dissolved oxygen (DO) level is of capital importance in the field of environmental monitoring, food fermentation, industrial production, and clinical medicine. Optical oxygen sensors with high sensitivity, accuracy, stability, and anti-jamming capability for DO content detection have provoked scientists’ attention in recent years. In this work, we selected platinum octaethylporphine (PtOEP), low-density polyethylene (LDPE), and high-density polyethylene (HDPE) as the fluorescent indicator and matrix materials, respectively. Porous LDPE/PtOEP and HDPE/PtOEP oxygen-sensing films were constructed by incorporating PtOEP in PE via the phase-separation method. The optimum parameters were obtained as follows: the concentrations of LDPE and HDPE solutions were 0.010 mg/L, and PtOEP was 8 μg. Based on the above study, the effects of different kinds of PE on the performance of the oxygen-sensing film were studied in detail, finding that the LDPE/PtOEP oxygen-sensing film had better photostability and could measure the DO concentrations of several water samples accurately.

Lithium metal, as the most ideal anode material for high energy density batteries, has been researched for several decades. However, the dendrite formation and large volume change during repetitive lithium plating/stripping lead to a serious safety issue and impede the practical application of lithium metal anode. Herein, a nanoporous Ni foam current collector with high surface area and surface flaws is constructed via a facile oxidation–reduction method. The inherent macropore structure of Ni foam can partly accommodate the volume variation during Li plating/stripping. The well-distributed nanopores on the skeleton of Ni foam can effectively reduce the local current density, regulate the uniform lithium nucleation and deposition with homogenous distribution of Li+ flux. Moreover, the surface flaws induce the formation of ring Li structures at initial nucleation/deposition processes and concave Li metal spontaneously formed based on the ring Li structures during cycling, which can direct the even Li plating/stripping. Therefore, highly stable Coulombic efficiency is achieved at 1 mA cm−2 for 200 cycles. The symmetrical cell, based on the nanoporous Ni foam current collector, presents long lifespans of 1200 and 700 h respectively at different current densities of 0.5 and 1 mA cm−2 without short circuit. In addition, the LiFePO4 full cell, with the Li metal anode based on the nanoporous Ni foam current collector, shows excellent cycling performance at 1C for 300 cycles and rate performance.

Converting solar energy efficiently into hydrogen is a promising way for renewable fuels technology. However, high-temperature heat transfer enhancement of solar thermochemical process is still a pertinent challenge for solar energy conversion into fuels. In this paper, high-temperature heat transfer enhancement accounting for radiation, conduction, and convection heat transfer in porous-medium reactor filled with application in hydrogen generation has been investigated. NiFe-Aluminate porous media is synthesized and used as solar radiant absorber and redox material. Experiments combined with numerical models are performed for analyzing thermal characteristics and chemical changes in solar receiver. The reacting medium is most heated by radiation heat transfer and higher temperature distribution is observed in the region exposed to high radiation heat flux. Heat distribution, O2 and H2 yield in the reacting medium are facilitated by convective reactive gas moving through the medium's pores. The temperature gradient caused by thermal transition at fluid-solid interface could be more decreased as much as the reaction chamber can store the transferred high-temperature heat flux. However, thermal losses due to radiation flux lost at the quartz glass are obviously inevitable.

Carbon materials with high electronic conductivity and high surface area show obvious advantage as anode material for commercial sodium-ion batteries. Here, carbon nanotubes (CNTs) with porous and disordered structures (PCNTs) are synthesized via a facile K2CO3-assisted activation method. The open porous structures (specific surface areas of 444 m2 g−1) and abundant defects (O defects content of 7.2 at%) may not only shorten the transport path of Na ion, increase contact interface between electrolyte and electrode, but also facilitate the reversible capacity of Na storage. In addition, the 3D CNT conductive network improves the electronic conductivity. PCNT anode displays a favorable reversible capacity of 255 mAh g−1 after 200 cycles at 0.1 A g−1, with an initial Coulombic efficiency of 60% and excellent rate capability of 187 mAh g−1 at 2.00 A g−1. This work gives a simple strategy for manufacturing porous CNT anode for advanced energy storage devices.

The electrochemical CO2 reduction (ECR) to produce valuable chemicals and fuels using clean energy resources is a promising and effective route to support energy storage and reduce the large CO2 concentration to avoid climate change. Among the presently adopted CO2 conversion technologies, electrochemical CO2 reduction (ECR) to valuable feedstock is presently a concern of critical research effort as a technology that can concurrently enable CO2 reduction and the storage of renewable energy. The ECR performance and economic viability are greatly influenced by the intrinsic characteristics of the catalyst employed. Many techniques have been practiced to improve the catalytic performance of heterogeneous catalysts by administering their morphology, size, crystal facets, grain boundaries, and surface defects and their integration with other synergistic constituents to fabricate nanomaterials. Presently, the fabrication of nanomaterials at the atomic level is an effective and strong technique to address the particular issues of catalytic performance and durability in ECR, by comprehending the structure–performance relationship of the nanomaterials. Herein, we present the recent technological advances with metal-derived nanomaterials, discussing the factors affecting their catalytic performance, their mechanism, and applications for the selective production of formic acid, carbon monoxide, alcohols, and hydrocarbons. Moreover, different commonly-adopted fabrication techniques for the synthesis of nanostructures have been incorporated to outline their working principles and their specialty to produce different kinds of nanostructures (nano-polyhedrons, nanowires, dendrites, and nano-frames).

Electrochromic (EC) smart windows regulate the indoor solar radiation by adjusting the optical transmittance, offering an efficient solution toward energy-saving buildings. Tungsten oxide/nickel oxide (WO3/NiO) solid-state devices are most likely to be industrialized among all the electrochromic devices (ECDs). However, there are still some problems in WO3/NiO-based solid-state electrochromic devices (ECDs), such as inflexibility, low visible light contrast, slow response speed, and poor stability in the switching process due to the charge capacity mismatch of WO3 and NiO layers. Moreover, the whole charge capacity of the ECDs depends on the charge capacity of NiO layers, which is extremely less than that of WO3 layers. Therefore, high charge capacity NiO films are in urgent demand for the fabrication of high-performance WO3/NiO solid-state ECDs with long-life stability. In order to improve these properties and overcome the mismatch problem with WO3, 2–8 wt% of H2O is added to the lithium electrolyte, which can provide hydroxide ions to participate in the electrochromic reaction of NiO films. Thus, high charge capacity (7 times enhanced than that in the anhydrous electrolyte) and high optical modulation (59.5% at 511 nm) of NiO films can be obtained. More importantly, due to the low content, OH− can be fixed on the NiO films as NiOOH, which will not erode WO3 films in devices. Hence, solid-state electrochromic devices with the structure of ITO/WO3/electrolyte/NiO/ITO were assembled, exhibiting excellent optical modulation of 62% and long-life stability up to 10 000 cycles without attenuation. Furthermore, flexible and large-area devices can also be obtained, which is important for a wide range of scientific and industrial processes.

To circumvent the imbalances of electrochemical kinetics and charge-storage capacity between Li+ ion battery anodes and capacitive cathodes in lithium-ion capacitors (LICs), dual carbon based LICs are constructed and investigated extensively. Herein, S, O dual-doped 3D net-like porous carbon (S-NPC) is prepared using waste paper as the carbon source through a facile solvothermal treatment and chemical activation. Benefiting from the combination effect of the rich S,O-doping (about 2.1 at% for S, and 9.0 at% for O), high surface area (2262 m2 g−1) and interconnected porous network structure, the S-NPC-40 material exhibits excellent electrochemical performance as both cathode material and anode material for LICs. S, O doping not only increases the pseudocapacity but also improves the electronic conductivity, which is beneficial to reduce the mismatch between the two electrodes. The S-NPC-40//S-NPC-40 LIC delivers high energy densities of 176.1 and 77.8 W h kg−1 at power densities of 400 and 20 kW kg−1, respectively, as well as superior cycling stability with 82% capacitance retention after 20 000 cycles at 2 A g−1. This research provides an efficient method to convert waste paper to porous carbon electrode materials for high performance LIC devices.

Free-standing aligned fiber is capable of providing sufficient electrochemical properties for fiber electrode without sacrificing flexibility, which is highly desirable for fiber batteries that are expected to be flexible and efficient energy storage. Here, we propose a free-standing and aligned tungstate/MXene fiber spun from their mixed liquid crystals colloid for fiber-shaped lithium/sodium-ion batteries. Benefiting from the 3D interconnected ion transport tunnels, fast charge transfer frameworks and minimum ion-path tortuosity provided by the aligned structures of 2D tungstate and MXene nanosheets, the fiber is endowed with both efficient pseudocapacitive energy storage and flexibility. As expected, the fiber delivers high reversible capacity, excellent rate capability and outstanding long-term cycling performance. Even under mechanical deformations, the fiber batteries can power the LED, digital timer, temperature-humidity meter, and smart wristband. This work may promote the further development of practical fiber batteries for wearable electronics.

In this work, the effect of coagulation bath temperature in different solvent systems [1,4-butyrolactone (GBL)/N,N-dimethylacetamide (DMAC)] on the structure and dielectric properties of polyimide (PI) films was investigated for the first time. The solubility parameter was introduced to explain the formation process of porous PI films. The results showed that the changed tendency of the dielectric constant versus temperature is opposite for the single-solvent system and cosolvent system. For a single DMAC and GBL solvent, the dielectric constants of the films decreased with increasing temperature. In contrast, the dielectric constants increased with the increase in temperature for the GBL/DMAC cosolvent system. Moreover, the measured porosities were applied to estimate the dielectric constants of the PI films. This showed that the porosity increased with increasing temperature for a single-solvent system, while it decreased for a cosolvent system. Scanning electron microscopy images suggested that the variation trends are derived from the different influences of the temperature on the structure and morphology. Thus, this study reveals the effect of coagulation bath temperature on the structure and dielectric properties of porous PI films and provides the guidance for the design and optimization of architectures for high-performance porous films.

The performance of electrochromic supercapacitors (ESCs) can be improved by the use of electrodes with high electronic conductivity and ion transport ability. Herein, two-dimensional (2D) N-doped NiO ultrathin nanosheets (N-NiO UTNSs) synthesized in situ on fluorine-doped tin oxide glass were used as bifunctional ESC electrodes. These electrodes exhibited an elevated specific capacitance (540 F g−1 at 1 A g−1), superior cycling stability (85% capacitance retention after 10,000 cycles), and good electrochromic properties (color change from colorless to black with a transmittance modulation of 73% and a coloration efficiency of up to 83.47 cm2 C−1 at 550 nm), which was ascribed to the high electronic conductivity of NiO (due to N doping) and the short ion diffusion path (due to the ultralow nanosheet thickness). To further explore the practical applications of N-NiO UTNSs, we constructed asymmetric ESCs by integrating NiO films with Fe2O3 films and revealed that these devices displayed applied voltage–dependent colors. Two charged asymmetric ESCs connected in series could light up a red light-emitting diode and changed color synchronously with charge state alteration. Thus, our results contribute to the development of Ni-based electrochromic supercapacitors exhibiting charge state-dependent color changes.

Vanadium dioxide is a well-known phase-change material on account of its unique changes of optical property, which has seen a great increase in its implementation for the regulation of thermal radiance. However, the fabrication of VO2 needs strict conditions for its narrow sliver in the phase diagram. In this paper, in situ preparation of VO2 films by high-power impulse magnetron sputtering is proposed, in which ionized flux density is used to direct the crystal growth. Besides, the surface structure and thermochromic behaviors of the deposited films are studied in detail. Furthermore, simulations are carried out for the sake of optimizing the thickness of VO2 films with the largest emissivity modulation ability, and the experimental result reveals that their tuning range reaches up to 0.32. It is believed that our work will find wide applications not only in fundamental material science but also in thermal radiance regulation.

The density and pore diameter of aluminum (Al) films have an important influence on the resultant film applications, especially in the field which require extremely high-density, uniform Al films. In this study, Al was electrodeposited from 1-ethyl-3-methyl imidazolium chloride ([EMIm]Cl) ionic liquid onto a Ni substrate using AlCl3 as the Al source. The results show that the concentration of the electrolyte was the crucial factor governing the microstructure of the electrodeposited continuous and dendrite-free Al film. The obtained continuous, dendrite-free Al film was used as the anode of a Li-ion battery. The obtained Al films delivered a first specific capacity reaching 1492 mAh g−1 in the Li-ion battery and effectively improved the corrosion resistance of the Ni substrate.

The energy and environmental crises have forced us to search for a new green energy source and develop energy storage and environmental restoration technologies. Fabrication of carbon functional materials derived from coal has attracted increasing attention in the energy storage and gas adsorption fields. In this study, an N, O-co-doped porous carbon/carbon nanotube composite was prepared by functionalizing coal-based porous carbon with carbon nanotubes (CNTs) and ionic liquid via annealing. The resulting material not only inherited the morphology of CNTs and porous carbon, but also developed a three dimensional (3D) hierarchical porous structure with numerous heteroatom groups. The N, O co-doped porous carbon/CNT composite (N, O-PC-CNTs) showed a surface area of 2164 m2 g−1, and a high level of N/O dopants (8.0 and 3.0 at%, respectively). Benefiting from such merits, N, O-PC-CNTs exhibited a rather high specific capacitance of 287 F g−1 at a current density of 0.2 A g−1 and a high rate capability (70% and 64% capacitance retention at 10 and 50 A g−1, respectively) in a three electrode system. Furthermore, an N, O-PC-CNT symmetrical supercapacitor showed a high cycling stability with 95% capacitance retention after 20 000 cycles at 20 A g−1 and an energy density of 4.5 W h kg−1 at a power density of 12.5 kW kg−1 in 6 mol L−1 KOH electrolyte. As a CO2 adsorbent, N, O-PC-CNTs exhibited a high CO2 uptake of 5.7 and 3.7 mmol g−1 at 1 bar at 273 and 298 K, respectively. Moreover, N, O-PC-CNTs showed cycling stability with 94% retention of the initial CO2 adsorption capacity at 298 K over 10 cycles. This report introduces a strategy to design a coal based porous carbon composite for use in efficient supercapacitor electrodes and CO2 adsorbents.

The unsafe deposition process and slow deposition rate of the electrolyte layers are the main obstacles for electrochromic devices (ECDs) toward commercial application. In this work, an ECD with a structure of glass/ITO/WO3/LiF/NiO/ITO has been prepared by electron beam and resistance evaporation methods. The LiF electrolyte is deposited by resistance evaporation with the LiF particles and shows promising potential as the Li+ based electrolyte in ECDs owing to its high transparency and good ionic conductivity. The ECD shows a fast response (4.0 s for bleaching and 9.6 s for coloring), large optical transmittance modulations (∼58.9% at 625 nm, 100 s for coloring), good stability and high coloration efficiency (88.5 cm2 C-1). This work not only indicates that LiF can be used as a Li+ based electrolyte in an ECD, but also paves a new way to fast and safe preparation of ECDs with high performance.

Macroscopic assembly of 2D nanomaterials, especially for the one-dimensional macroscopic ordered fiber assembly from 2D liquid crystals (LCs), is rising to an unprecedented height and will continue to be an important topic in materials. However, this case of 2D functional metal oxide nanosheets is quite challenging. For the first time, the high-performance tungstate macroscopic fiber has been realized through an LC wet-spinning process involving the formation of LC colloid with spinnability and performance improvement by interlayer bridging in macroscopic assembly. The resultant macroscopic fiber yields record high tensile strength (198.5 MPa) and fracture toughness (3.0 MJ m-3) owing to their highly ordered structure and strong ionic interlayer bridging. Despite the intrinsically weak mechanical strength of the nanosheets, with only a few percent of graphene, the fibers manifest mechanical properties comparable to that of graphene fibers. Inspired by this concept, the possible macroscopic fibers assembled from other 2D functional metal oxide nanosheets will become a reality in the near future, holding great promise in aerospace and wearable applications.

Fiber batteries have become increasingly important in the wearable energy market and thus, great efforts have been devoted to their development with better specific capacities, longer lifetimes, and sufficient flexibility. However, the sluggish kinetics of the ion transport in the electrochemical process has become a limitation for their practical applications. Herein, we directly employed 2D tungstate and graphene nanosheets as building blocks to construct fiber electrodes with 2D nanofluidic channels and 3D interconnected tunnels for exclusive and fast ion transport. These structures could accelerate the ionic transport process, avoiding the limitations from solid-state diffusion in the electrochemical process and finally facilitating efficient pseudocapacitive charge storage. The resulting fiber-shaped lithium- and sodium-ion batteries exhibited extremely high capacities (206 and 178 mA h g−1 for LIBs and SIBs, respectively), excellent rate performance, long-term cycling capability (1000 cycles), and outstanding flexibility (200 bending cycles), which could continuously light an LED even under mechanical deformations. Thus, this work provides new insights into the structural engineering of fiber electrodes, showing great promise for boosting the battery performances in actual wearable applications to new levels.

Electrochromic supercapacitors (ESCs) are appealing for smart electronic device applications due to their advantages of dual-function integration. Unfortunately, the synchronous dual-function evaluation and the essential reaction mechanism are ambiguous. Herein, we constructed a 3D WO3-x nanowire networks/fluorine-doped tin oxide (WO3-x NWNs/FTO) bifunctional electrode for ESCs by a solvothermal self-crystal seeding method. The synchronous correspondence relationship between the optical and electrochemical performances of the WO3-x NWNs/FTO electrode was explored using an operando spectra-electrochemical characterization method. It reveals an excellent areal capacity of 57.57 mF cm−2 with a high corresponding optical modulation (ΔT) of 85.05% and high optical-electrochemical cycling stability. Furthermore, the synergistic reaction mechanism between the Al3+ ion intercalation behavior and the surface pseudocapacitance reaction during electrochemical cycling is revealed utilizing in situ X-ray diffraction. Based on these results, an ESC device was constructed by pairing WO3-x/FTO as the cathode with V2O5 nanoflowers/FTO (V2O5 NFs/FTO) as the anode, which simultaneously deliver high capacity and large optical modulation. Moreover, the energy storage level of the ESC device could be visually monitored by rapid and reversible color transitions in real time. This work provides a promising pathway to developing multi-functional integrated smart supercapacitors. The synchronous correspondence relationship between the optical and charge storage performances, and the synergistic intrinsic mechanism between the Al3+ ion intercalation and the surface pseudocapacitance reaction affecting the electrochromic-energy storage performance are revealed using in-situ/operando techniques.

This study reports a simple imprinting method for the fabrication of biomimetic moth-eye antireflective polymethyl methacrylate (PMMA) nanostructures on the surface of the substrate. The antireflection structured silicon was obtained by Reactive Ion Etching (RIE) method. By using the antireflection structured silicon substrate as the imprinting stamp, the biomimetic moth-eye polymer structures showed tapered holes, whose depth and periodicity were around 780 nm and 580 nm, respectively. The reflectance of the resulting PMMA structures was reduced from 10% to less than 1% in the wavelength range from 300 nm to 1600 nm. This simple methodology can be scaled up via self-loading and nanoimprinting, which may have a promising application in optoelectronic devices and solar cells.

Radiative cooling, as a passive way to dissipate heat into outer space without any extra energy, has attracted considerable attention recently. However, the metal reflector of the conventional cool...

Nanoscale microstructure designing is playing an important role in improving the performance of electrode materials of an electrochemical battery. The Sn based anode is among the very high-capacity but less-stable materials, and has been used mostly for anode of the Li-ion battery with unsatisfactory performance. In this work, we design a new type of 3D porous graphene and nano-Sn composite (Sn/Void@G) by simple one-step annealing of graphene oxide, polystyrene spheres and stannic chloride for both high performance Li- and Na-ion battery anodes. More importantly, the 3D porous graphene formed tunable micro-nano void as a highly efficient “bumper” to accommodate the large volume expansion of nano-Sn particles. As results, the discharge specific capacity of the Sn/Void@G, anode still remains 45.3% while the charge-discharge current is increased 50 times, and the capacity is more than 400 mAh g−1 after 500 cycles at 5C rate. For Na storage, the integrated anodes deliver the Na storage capacity of 786.1 mAh/g at 0.1C rate and the capacity of more than 340 mAh/g after 800 cycles at 2C rate. The present result on Li and Na ion battery may pave the way to next generation high power and energy density batteries.

Although the properties of electrochromic materials (ECMs) have been enhanced using fabricated porous materials, the effect of materials porosity on such an enhancement remains unclear. Here, we report a novel ECMs with an adjustable pore hierarchy based on quasi-amorphous and ordered arrays of SiO2@Fc(COCH3)2. ECMs with different pore systems were generated by modifying Fc(COCH3)2 concentration and self-assembly temperature. The composition and core-shell structure of the SiO2@Fc(COCH3)2 nanospheres were confirmed through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and EDX mapping. The influence of adjustable pore system on the electrochemical behavior was studied. Experimental results showed that the current density of the redox couple peaks of the quasi-amorphous porous SiO2@Fc(COCH3)2 films are considerably lower than those of the ordered porous films but are higher than those of the dense Fc(COCH3)2 films. At 550 nm, the transmittance variation of the quasi-amorphous porous SiO2@Fc(COCH3)2 film is 19%, whereas that of the ordered porous film is 35%. The coloration and bleaching times of the quasi-amorphous porous SiO2@Fc(COCH3)2 film are 17.1 s and 4.5 s, respectively, whereas those of the ordered porous film are only 16.5 s and 3.5 s, respectively. Furthermore, the porosities of the films are solved numerically by the finite-element method. For the ordered porous SiO2@Fc(COCH3)2 film, the porosity is 0.26, while the quasi-amorphous film became larger (0.31–0.41). This work is the first step in combining ferrocene derivative and colloidal crystal porous structures to develop a green, simple and efficient electrochromic process.

In this study, monolayer hollow spherical tungsten oxide (WO3) films have been prepared for the first time by magnetron sputtering combined with the colloidal crystal template method. Due to the large specific surface area, short ion diffusion distances, and weak scattering of the monolayer hollow structure, the hollow spherical WO3 film exhibits excellent electrochromic performance. This includes high transmittance modulation in the near-infrared spectral range (78.8% at λ = 1000 nm), fast switching response time (2.41 s for coloration and 1.28 s for bleaching), and high coloring efficiency (102.9 cm2 C−1) at 1000 nm. The results show that the hollow spherical WO3 film can effectively regulate incident light, especially in the near infrared band, which is not visible but has significant thermal effects.

In this study, camphorsulfonic acid (CSA)-doped polyaniline (PANI) films have been prepared on the surface of an Au/nylon 66 porous flexible substrate by electrochemical deposition. The feature of the research was that utilize an Au layer deposited onto a porous flexible substrate to deposite CSA-doped PANI film for modulation infrared emissivity at first time. The morphology of Au/nylon 66 flexible substrate and PANI films and the electrochromic properties of CSA-doped PANI film were investigated in detail to obtain a PANI film that possesses highly infrared modulation ability. The emissivity variation Δe was achieved as of 0.225, 0.399, and 0.426 in the wavelength ranges of 3–5, 8–12, and 2.5–25 μm, respectively. The switching times of the CSA doped-PANI film for the coloration and bleaching are 6 s and 2.5 s, respectively. The IR electrochromic film investigated in this work may find an application in IR devices for IR camouflage and thermal control.

Hard carbon with high special capacity has been widely studied as anode for sodium ion batteries (SIBs). Its storage sodium performance still needs to be further improved. Herein, a composite electrode was synthesized through growing V2O5 nanosheet array on free-standing hard carbon fiber fabric by solvothermal reaction. The electrochemical properties of the composite electrode were significantly enhanced compared with pure hard carbon fiber electrode. The composite showed a specific capacity from 241 mA h g−1 at 50 mA g−1 to 77 mA h g−1 at 1000 mA g−1 and a good cycling ability of 184 mA h g−1 after 100 cycles at 100 mA g−1. Except good storage Na ability for V2O5 nannosheets, the improvement of electrochemical performances also benefited from and the synergistic effect from the ability of fast electron transfer of hard carbon and the toleration for Na+ insertion of V2O5 nanosheet array, as well as the inhibitory effect on solid electrolyte interface (SEI) of nanostructure. Additionally, the free-standing electrodes could also increase the energy and power density. This will push the promising hard carbon material used as SIBs anode in practical applications.

Adaptive infrared (IR) electrochromic devices driven by electrical energy have considerable potential use in intelligent IR thermal management application in the future. Polyaniline (PANI) is regarded as an ideal material for IR electrochromic devices due to its intrinsic IR electrochromic properties. However, despite extensive study focusing on improving the IR electrochromic properties of PANI, few experiments have been performed for in-depth study of the IR electrochromic mechanism of PANI or to improve its variable IR emissivity efficiency. Herein, an HClO4-doped PANI porous film with excellent IR regulation ability was fabricated via in situ electrochemical deposition on an Au/microporous substrate, and the IR electrochromic mechanism of the PANI film was further elucidated. A combination of Raman spectra, UV-vis spectra, XPS analyses, transmittance curves and emittance curves of the PANI porous film in distinct conjugation states and corresponding dedoping states confirms that the most direct and critical factors for realizing the emissivity modulation of PANI films are the formation and the elimination of polarons and bipolarons delocalized on PANI chains. The key factor to achieve large amplitude emissivity modulation of PANI films is fully and effectively regulating the transformations between the various states of PANI. In addition, an IR electrochromic device was fabricated through assembly with HClO4-doped PANI porous films. The device can realize modulation of the emittance variation from 0.735 to 0.316 (Δe = 0.419) and of the radiation energy variation from 273.503 to 117.661 W m−2 (ΔP = 155.842 W m−2) in the wavelength range of 2.5 to 25 μm. Furthermore, the device assembled with nanoporous PE possesses lower α(s) and excellent IR control capability. Also, this study shows that the device can change its color by electrical control in a thermal imaging system; these demonstrations suggest its potential for the future development of intelligent IR thermal management applications.

Metamaterial absorber/emitter is an important aspect of infrared radiation manipulation. In this paper, we proposed four simple switchable infrared metamaterial absorbers/emitters with Ag/VO 2 disks on the Ag plane employing triangle, square, hexagon, and circle unit cells. The spectral absorption peaks whose intensities are above 0.99 occur at ~4 μ m after structure optimization when VO 2 is in insulating state and disappear when VO 2 becomes metallic state. The simulated electromagnetic field reveals that the spectral absorption peaks are attributed to the excitation of magnetic polariton within the insulating VO 2 spacer layer, whose values exceed 1.59 orders of magnitude higher than the incident magnetic field. Longer resonant wavelength would be excited in square arrays because its configuration is a better carrier of charges at the same spans. For absorption stability, the absorbers/emitters with square and circular structures do not have any change with the polarization angles changing from 0° to 90°, due to the high rotational symmetric structure. And four absorbers/emitters reveal similar shifts and attenuations under different incident angles. We believed that the switchable absorber/emitter demonstrates promising applications in the sensing technology and adaptive infrared system.

Several kinds of polyimide (PI) films stemmed out of 4, 4&rsquo, &ndash, diaminodiphenyl ether, as well as various structurally various aromatic dianhydride, were prepared. The films&rsquo, mechanical, dielectric, and dynamic mechanical attributes were put under investigation. According the findings, the PI films&rsquo, performance is significantly different as a result of their diverse structure. PI&rsquo, s dielectric constant and dielectric loss tangent of abides by the increasing order below: PMDA-PI&gt, BTDA-PI&gt, BPDA-PI. Moreover, the electric breakdown strength of BTDA-PI (478.90 kV/mm) presents a lot higher value compared to the one PMDA-PI (326.80 kV/mm) and BPDA-PI (357.07 kV/mm). In particular, BTDA-PI film possesses high electric breakdown strength about 478.90 kV/mm. In addition, PI&rsquo, s glass transition temperature (Tg) are, respectively, 276 &deg, C (BTDA-PI), and290 &deg, C (BPDA-PI), as well as 302 &deg, C (PMDA-PI). Therefore, in virtue of their various structures and performances, practical applications of PI films can exert significant role in the electronics and microelectronics industries.

Precise optical and thermal regulatory systems are found in nature, specifically in the microstructures on organisms' surfaces. In fact, the interaction between light and matter through these microstructures is of great significance to the evolution and survival of organisms. Furthermore, the optical regulation by these biological microstructures is engineered owing to natural selection. Herein, the role that microstructures play in enhancing optical performance or creating new optical properties in nature is summarized, with a focus on the regulation mechanisms of the solar and infrared spectra emanating from the microstructures and their role in the field of thermal radiation. The causes of the unique optical phenomena are discussed, focusing on prevailing characteristics such as high absorption, high transmission, adjustable reflection, adjustable absorption, and dynamic infrared radiative design. On this basis, the comprehensive control performance of light and heat integrated by this bioinspired microstructure is introduced in detail and a solution strategy for the development of low-energy, environmentally friendly, intelligent thermal control instruments is discussed. In order to develop such an instrument, a microstructural design foundation is provided.

Vanadium dioxide (VO2)-based thermochromic coatings has attracted considerable attention in the application of smart windows as a result of their intriguing property of metal–insulator transition a...

Electrochromic-supercapacitors (ESCs) have shown great perspective in multifunctional smart devices due to their special function of monitoring the energy storage level by the visible color changes. However, the poor areal capacitance at high optical modulation(ΔT) and the inferior bifunctional lifespan hinder the practical application of ESCs. It is thus important to develop feasible ways to boost the optical-electrochemical properties and comprehend the corresponding inner mechanism. Inspired by nature’s conifer structure, herein, 3D hexagonal WO3 branched nanowire arrays/F-doped SnO2 (h-WO3 BNW/FTO) electrode have been successfully constructed via a single-step hydrothermal reaction followed by annealing process. Such biomimetic conifer-like structure is shaped by the separating crystal growth effect coupled with the specific topological structure of h-WO3. Benefiting from bionic structure, h-WO3 BNW/FTO electrode delivers a high areal specific capacity (0.0223 mAh cm-2) and large corresponding ΔT respond (80% ΔT at 650 nm) at 5 mV s-1, as well as outstanding optical-electrochemical cycle stability. Moreover, the aluminum storage mechanism during the optical-electrochemical process is affirmed using cyclic voltammetry and in-situ X-ray method. For practical application, the assembled ESC device based on the h-WO3 BNW/FTO electrode delivers a high 22.75 mF cm-2 areal specific capacitance, corresponding 45.81% ΔT (at 650 nm) and long-term bifunctional stability (over 90% bifunctional retention after 5000 cycles). Meanwhile, the visually monitoring capacity of the device is realized through the color changes. This study provides some insights into the biomimetic design for advanced bifunctional electrodes and the underlying mechanism affecting the electrochromic-charge storage performance.

Considering the increasing demands in energy storage systems (ESS), the nitrogen doped porous carbons with high volume properties are urgently needed in practical applications. Herein, we develop a new strategy for the fabrication of the high density and nitrogen-doped porous carbons (DNPCs) via low-temperature pyrolysis of phytic acid (PA)-doped polyaniline (PANI) coated on graphene, representing a high volumetric performance as supercapacitor electrode materials. PA is used to form the graphene oxide/polyaniline (GO/PANI) precursor, protect GO from agglomeration, reduce the porosity and regulate the heteroatoms contents of porous carbon. Benefiting from PA-inducing and low-temperature pyrolysis, the DNPC-500 performs a high volumetric capacitance of 643.7 F cm−3 at 0.5 A g − 1, and outstanding rate performance respectively. In a symmetric supercapacitor, the DNPC-500 device possesses a high volumetric energy density of 14.6 W L − 1 at the power density of 79.8 kW L − 1. Thus, this result exhibits a novel design of high density and nitrogen doped porous carbon materials for supercapacitors.

A flexible reflective-type electrochromic device based on PB films has been constructed. Based on the subtractive color-mixing theory, the demonstrated electrochromic device exhibits a unique reversible color changes from leaf-green to sand-yellow by electrochemical operation. Fast response time of 0.9 s for bleaching and 1.3 s for coloring is observed, which is faster than most reports. In addition, the device exhibits high electrochromic stability of more than 100 cycles without compromising its performance. The flexible device shows promise for a broad range of potential application in the wearable electrochromic displays and camouflage.

A NiOx film with varying crystallinity across film thickness has been prepared by reactive radio frequency magnetron sputtering. The main research achievement is that the electrochemical cycling stability of the NiOx film has been radically improved as compared with NiOx films deposited by the conventional technologies. At the same time, the optical modulation has been also improved, whereas other electrochromic parameters, such as the switching rate and high coloration efficiency have been preserved at the required level.

High-capacity anode materials for lithium ion batteries (LIBs), such as Ge, generally suffer tremendous volume changes, as a result of the conversion reaction mechanism with Li, severely impede the high rate and cycling performance toward their practical application. In this article, we demonstrate a general LIBs Ge composites electrodes fabrication method using electrodeposition from room temperature ionic liquid. Our process is capable of forming composites electrodes with carbon nanotubes (CNTs), reduced graphene oxide (RGO), poly (3,4-ethylenedioxythiophene) (PEDOT), without the additives and conductive agents. During the electrodeposition process, Ge nanoparticles are integrated into the substrate network. Benefiting from the porosity, conductive network and mechanical stability constructed by interpenetrated compound layers, the hybrid system synergistically enhances the intrinsic properties of each component, yet is robust and flexible. The Ge/CNTs, Ge/RGO and Ge/PEDOT composites retain capacities of ∼851, 1212, and 1300 mAh/g after 200 cycles at 0.1 C. SEM analysis suggests that Ge/PEDOT composites have flower-like hierarchically porous structure, during cycling this structure transforms into a porous network, which can mitigate the physical strains during the Li uptake/release process, and increase the interfacial contact area with organic electrolyte. Consequently, the Ge/PEDOT composites demonstrate greatly enhanced rate capability without obvious capacity fading at high rate of up to 5 C.

We present a facile method to prepare W - doped VO2 films with lowered phase transition temperature (Tt), narrowed hysteresis loops width (ΔTt) and excellent cycle stability. The W - doped VO2 films have been obtained by inorganic sol - gel method. And W dopant is introduced by pouring melt V2O5 into ammonium tungstate solution. The properties of the samples are measured by XRD, XPS, SEM and transmittance spectra. The Tt is reduced from 73 °C to 20 °C along with the ΔTt narrowed from 10 °C to 4 °C as W dopant increasing from 0 to 3.2 at%. Besides, no obvious attenuation is observed on crystal structure, variation of transmittance (ΔT2000nm), Tt and ΔTt for W - doped VO2 films after 550 alternate heating and cooling cycles, while the pure VO2 films show obvious degradation. Since the surface morphology has no obvious changes after 550 cycles, it suggests that the W dopant induced distorted crystal structure strengthen the cycle stability of W - doped VO2 films. These encouraging results show great potential and understanding of VO2 films for practical applications.

A improved bifunctional nanostructure composite was designed and fabricated as reversible electrodes for electrochromic film and lithium-ion battery. This unique optic-electro responsive urchin-like architecture assembled from WO3@PANI nanobelts were prepared by solvothermal and electropolymerization methods. As expected, the composite exhibits the superior optical-electrochemical performances. The composite owns quick switching time ranging from purple, green, yellow, gray to blue via voltage regulation, better rate performance and long-term cycling stability in the galvanostatic charge/discharge process. Benefited from stable structure and short diffusion path, it also demonstrates a distinct optical modulation (△T = 45%) and excellent durability after long-term cycles (1200 cycles). The as-prepared electrode exhibits outstanding cycling stability (capacity retention of 516 mAh g−1 after 1200 cycles with a low average fading capacity of ca. 0.103 mAh g−1 and fading cyclic rate of ca. 0.02% per cycle). The long-term stability studies reveal that urchin-like composite has much more excellent optical and electrochemical durability. The morphology and structure of the composite were carried out by characterization equipment. This effective synthesis strategy will have profound implications for developing the other inorganic–organic nanocomposites in optical and electrochemical field.

Germanium (Ge) is an important semiconductor material in optoelectronic devices and is being researched in energy storage fields. Ge nanostructure materials with different morphologies may lead to distinctly different application performances. In this work, Ge nanorod architectures were successfully template-free electrodeposited on ITO substrate from the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([Emim]Tf2N) containing dissolved GeCl4 with the assistance of UV light. The UV irradiation influences the conformation of imidazolium rings of [Emim]+ adsorbed during the deposition process. A solution template has been formed on the surface of the electrode which inhibited the lateral growth of Ge nuclei and promoted the growth of Ge nanorod structures. Consequently, the coral-like Ge nanorod bundles (NRBs) has been obtained. This method provides attractive prospects for the other semiconductor nanorod structures.

Self-assembly technology of sub-micrometer-sized colloidal particles is the most promising approach for the preparation of large-area Photonic Crystals (PCs). However, PCs obtained by this method are facile to be destroyed by external factors such as friction, impact, and pollutants. The highly keratinized epidermis of chameleon skin acts as a protective role for the dermis with photon cells of the tunable band-gap structure. Inspired by the epidermis structure of chameleon, we use whey protein to develop a sort of protective film on the surface of artificially synthesized PCs. The film possesses positive mechanical properties that make the PCs friction and impact resistant. In addition, favorable resistance to water and CO2 could prevent PCs from being destroyed by pollutants. Consequently, PCs with protective film are well preserved when subjected to external factors (such as friction) and the optical properties of the PCs are successfully maintained, that may significantly promote the utilization of PCs in optical devices.

Sodium-ion hybrid supercapacitors have received great attracts for next-generation energy storage applications due to their high energy and power densities, as well as the abundant sodium resource. However, electrodes based on transition-metal oxides often suffer from low reversible capacity and sluggish redox kinetics, which seriously constrains the rate and cycling performance of the devices. Herein, a facile two-step hydrolysis synthesis is used to prepare uniform sandwich-like mesoporous Nb2O5/graphene/mesoporous Nb2O5 (G@mNb2O5) nanosheets as sodium storage materials. The mesoporous Nb2O5 layers on graphene are constructed by several nanometer-sized Nb2O5 particles. In virtue of the structural features, the G@mNb2O5 nanosheets electrode demonstrates high-rate capacity (293 and 125 mA h g−1at 50 and 2000 mA g−1, respectively) and stable cycling performance due to the rapid redox kinetics, including significantly increased surface pseudocapacitive contribution, improved sodium-ion diffusion coefficient, and short characteristic relaxation process. By employing activated carbon as cathode, a full sodium-ion hybrid device successfully demonstrates a high energy density of 56.1 Wh kg−1 at 120 W kg−1, and 9.7 Wh kg−1 at 7200 W kg−1, as well as a stable capacitance retention of ∼ 89% at 1 A g−1. The availability of capacitive Na-ion storage system presented here is attractive for cost-effective energy storage applications.

In this work, a novel pyrrolic nitrogen-doped carbon sandwiched monolayer MoS2 hybrid was prepared. This sandwiched hybrid vertically anchors on graphene oxide as anode materials for sodium-ion batteries. Such electrode was fabricated by facile ionic liquid-assisted reflux and annealing methods. Owing to rational structure and enhancement from pyrrolic nitrogen dopant, this unique MoS2/C-graphene hybrid exhibits reversible specific capacity of 486 mAh g−1 after 1000 cycles with a low average fading capacity of 0.15 mAh g−1 (fading cyclic rate of ca. 0.03% per cycle). A capacity of 330 mAh g−1 is remained at the current densities of 10.0 A g−1. The proposed strategy provides a convenient way to create new pyrrolic nitrogen-doped hybrids for energy field and other related applications.

Polyimide (PI) film is usually considered as a valuable pyrolysis precursor of graphitized films applied in various electrodes and batteries. In this work, reduced graphene oxide (RGO) sheets were chosen as the catalysts to improve the graphitization properties of PI film. To analyze the structural evaluations, the crystalline growth process with RGO increasing was carefully investigated by transmission electron microscope (TEM) and the crystalline sizes were calculated by X-ray diffraction (XRD) and Raman spectra. The obvious induced effects were confirmed in graphitization of RGO/PI composites at 2300 °C. Finally, the electrical properties of as-prepared RGO/graphite composites were also improved with RGO increasing.

Traditional superhydrophobic material use depends on two processes: creating a rough structure on a material surface and modifying the rough surface with low surface energy materials. However, common preparation methods are time-consuming, complex and cost-ineffective. Furthermore, these methods usually rely on chemicals, and evidently that will restrict mass preparation and application of superhydrophobic materials. This study reports a simple polypropylene (PP) solution-based process for producing PP hierarchical structures on commercial copper mesh (low surface energy materials), without modifying the low surface energy materials. The hierarchical structures of copper meshes, surface modified with PP, can be rationally controlled by optimizing the PP concentration. The obtained copper mesh showed contact and rolling off angles of 162° and 7°, respectively. Importantly, no significant performance loss was observed after the superhydrophobic copper meshes were continuously and drastically rinsed with 3.5 wt% NaCl solution, or repeated tearing with an adhesive tape for more than 30 cycles, indicating its good durability. After surface modification with PP particles, the copper mesh exhibits both excellent superhydrophobicity and superoleophilicity. Additionally, the as-prepared copper mesh can self-float on water surface when deformed into a "miniature boat" shape. Meanwhile, self-driven spilled oil cleanup was achieved using a superhydrophobic copper mesh-formed miniature boat. The miniature boat can realize energy conservation as well as high efficiency. The cleanup rate of the boat is as high as 97.1%, demonstrating its great potential in environmental remediation applications.

Efficient electrodes with impressive storage capability and fast ion transfer rate are urgently needed to meet the demand for higher energy/power densities and longer life cycles and large rate powering devices. Through a simple freeze-drying and annealing process, nitrogen-containing porous carbon materials with a hierarchical porous structure and enlarged lattice spacing between graphene layers are synthesized. Benefiting from an improvement in the electrochemical activity, porosity, conductive network and mechanical stability, the porous carbon used as anodes for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) exhibits an excellent storage capability, rate performance, and cyclability. Apple carbon exhibits a high capacity of 1050 mA h g−1, and celery carbon shows the reversible capacities of 990 mA h g−1 at 0.1 A g−1 after the 200th cycle as LIBs anodes. For SIBs, a high capacity of 438 mA h g−1 is obtained after 200 cycles for apple carbon and 451 mA h g−1 for celery carbon. It is noteworthy that celery carbon shows a capacity retention of 94% between the 50th to 200th cycling. Further analysis on the structure characterization and charging curves reveal that celery carbon has a high N content, dilated intergraphene spacing, and an intrinsically hierarchical porous structure, which are capable of reversibly accumulating sodium ions through surface adsorption and sodium intercalation. Also, the electrochemical impedance spectroscopy (EIS) reveals that celery carbon has a low charge-transfer resistance, the enhanced cyclability and rate performance might be attributed to convenient ion diffusion in the electrode.

Smart electrochromic windows integrated with electrochemical energy storage capacity are receiving increasing interest for green buildings. However, the fabrication of bifunctional devices that demonstrate high-rate capability with stable and desirable optical modulation still remains a great challenge. Herein, a facile sacrificial template-accelerated hydrolysis approach is presented to prepare a designed lithium-ion insertion-type material layer on a fluorine-doped tin oxide substrate, with TiO2 mesoporous nanotube array (MNTA) film as an example, with rapid Li-ion insertion kinetics and without sacrificing window transparency, to meet requirements. A bifunctional device is assembled to exhibit the optical-electrochemical superiority of MNTA nanostructures. The as-assembled bifunctional smart window exhibits strong electrochromic contrast and high-rate capability in the fast galvanostatic charge/discharge process. For instance, at 1 A g−1, it completes the charge or discharge process within only 232 s and delivers a high, reversible and stable specific capacity of 60 mA h g−1, accompanying obvious transmittance modulation in the visible spectrum, with a typical value of ca. 30.4% at 700 nm, and strong color changes between deep blue and transparency.

The lack of high-performance tactile sensors, especially for pressure/force, is a huge obstacle for the widespread application of intelligent robots. Current pressure sensors are often operated in the high range of pressure and normal direction, showing a little ability in the low range of pressure and three-axis direction simultaneously. Herein, a highly sensitive flexible tactile sensor with three-axis force sensing capacity is presented by combining microstructured polydimethylsiloxane (PDMS) arrays and a reduced graphene oxide (rGO) film. The deformation of microstructured rGO/PDMS results in a change in the contact area between the rGO film and electrode, leading to a high sensitivity of -1.71 kPa-1 in the low range pressure of 0-225 Pa with a fast response time of 6 ms at a large feature size of 100 μm. To realize three-axis sensing, a sensing unit was built up, which was composed of the adjacent four parts of patterns and electrodes underneath a bump. A mechanical model of the exerted spatial force was established to calculate each axis force component via the deformation of the rGO/PDMS pattern. The experimental results show that the current difference between the adjacent two parts has a strong relationship with the applied force. As a proof of concept, we have demonstrated a 3 × 3 array sensor for arbitrary force sensing. Our tactile sensor would be used in transmitting information from a gentle spatial force and would exhibit broad applications as e-skin in integrated robots.

A reversible, persistent electrochromic change in color or optical parameter controlled by a temporarily applied electrical voltage is attractive because of its enormous display and energy-related applications. Due to the electrochemical and structural advantages, electrodes based on self-supported one-dimensional (1D) nanostructured materials have become increasingly important, and their impacts are particularly significant when considering the ease of assembly of electrochromic devices. This review describes recent advances in the development of self-supported 1D nanostructured materials as electrodes for enhanced electrochromism. Current strategies for the design and morphology control of self-supported electrodes fabricated using templates, anodization, vapor deposition, and solution techniques are outlined along with demonstrating the influences of nanostructures and components on the electrochemical redox kinetics and electrochromic performance. The applications of self-supported 1D nanomaterials in the emerging bifunctional devices are further illustrated.

Stretchable electrochromic devices (SECDs) have steadily attracted widespread attention in wearable devices. However, the delamination of device architectures (electrochromic layer, conductive layer and substrate) and poor chemical stability of conductive layer (silver nanowires (AgNWs)) are the key issues to be resolved to ensure the practical applications of flexible electrochromic devices. Herein, we designed a flexible and stretchable WO3@AgNW-PrePDMS (Pre-cured Polydimethylsiloxane) electrode, through integrated and embedded design, to build a high-performance electrochromic device. The integration of electrochromic layer and conductive layer in the electrode is fabricated via a WO3@AgNW core–shell structure. And embed the core–shell structure into the flexible substrate PDMS to form WO3@AgNW-PrePDMS electrode. This electrode architecture can prevent the delamination of the stretchable electrode during bending tests. Moreover, WO3 as a shell structure protects the conductive material AgNW to prevent its oxidation and improve the stability of the conductive substrate. The WO3@AgNW-PrePDMS electrode displays outstanding electrochemical stabilities and excellent bi-functionalities (flexible conductive film and electrochromic electrode): high conductivity (12 Ω/sq) as flexible transparent conductive film and wide optical modulation range (ΔT = 72% at 550 nm) as electrochromic electrode. The stretchable WO3@AgNW-PrePDMS electrode can still maintain stable electrical conductivity (ΔR/R≈8.3% and 14%) and electrochromic performance (90% and 92% retention) after 20,000 bending cycles and stretching to 70%, indicating the excellent mechanical flexibility. The WO3@AgNW core–shell nanowire network electrodes with embedded structures can be a strong candidate for wearable electrochemical energy devices in the future.