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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.

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 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.

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.

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.

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.

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.

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.

Heterogeneous interfaces interaction and multiscale nanostructures in two-dimensional (2D) materials hybrids are critically significant for realizing rate capability and long-life cycling performance. However, to strike a balance between minimizing the carbon content and maximizing the heterogeneous interfaces remains a critical challenge in nanoarchitectures for hybrid few-layers MoS2 with various carbonaceous materials. Here we present the ordered macroporous few-layered MoS2/C hybrid nanoarchitectures via a facile scalable in situ hybridization and spatial confinement strategies. Such hybrid strategies can maximize the MoS2 loading and restriction of MoS2 to a ultrasmall reaction. The optimized as-prepared hierarchical MoS2/C hybrids exhibit an initial capacity up to 631.2 mAh g−1 with a high first columbic efficiency of 81.16% for sodium-ion batteries (BILs) at 200 mA g−1. And, the electrodes display a high reversible capacity of 330.4 mAh g−1 with a long cycle life, superior cycling stability and excellent high-rate performance demonstrated rational designed hybrid architecture using as the electrodes in SIBs. This strategy could be proven to be an effective method for stabilizing the cyclability and improving in rechargeable rate performance for SIBs.

A series of novel conducting polyurethanes (PUs) with methoxyl triphenylamine (methoxyl-TPA) were synthesized from a new isocyanate with various dihydroxy monomers. The new isocyanate was prepared with p-anisidine and 4-fluoronitrobenzene. The structures of the designed polymers had been determined by FT-IR and 1H NMR. These polymers are amorphous and readily soluble in many polar organic solvents, such as N,N-dimethylformamide, dimethylacetamide and dimethyl sulfoxide. Similarly, the optical band gaps of PU-1, PU-2 and PU-3 are found to be 2.41, 2.51 and 2.44 eV, respectively. In addition, the polymers display excellent thermal stability, reversible electrochemical oxidation, high optical contrast ratio and electrochromic behavior from brown to cyan in the range of 0–1.5 V. High coloration efficiency of PU-2 arrives to 94.17 cm2 C−1.

This paper presents a detailed study of the influence of various parameters on refrigerated centrifugation (RC) of polymer colloidal crystals self-assembly. Refrigerated centrifugation could accuracy control the centrifugal temperature. Specifically, an experimental design using poly(styrene-methyl methacrylate-acrylic acid) (P(St-MMA-AA)) nanospheres was implemented to optimize the RC procedure by varying some parameters such as colloidal concentration, rotational velocity, and centrifugal temperature. The obtained colloidal crystals were characterized with respect to their morphology, periodicity, reflectance spectroscopy, and 3D surface roughness. The optimum conditions for RC fell in a narrow window, with which we obtained nearly perfect, crack-free, centimeter-sized, self-supporting, face-centered cubic colloidal crystals. The results demonstrate that the obtained P(St-MMA-AA) process parameters could be used as an operating template for other colloidal self-assemblies via refrigerated centrifugation.

Electrochromic (EC) materials have the ability to change their optical properties when exposed to a low electrical voltage. They have found a wide range of applications in smart windows, low-power displays, and spacecraft thermal control. To improve the practical applicability of EC materials, rational design and exploration of their architectures play a crucial role. Among various architectures, forms of inverse opal structure including two dimensionally and three dimensionally ordered macroporous structure (2DOM and 3DOM) exhibit outstanding and specific performance. In this review, several examples of 2DOM and 3DOM EC materials with detailed preparation methods are presented, followed by a detailed discussion of various aspects in ordered macroporous structural EC films, including common features, structure transition and photonic band gap tuning. In addition, the typical five layered design for the EC material-based device is given, as the device is of the most importance in researches as well as applications. Finally, conclusions and outlook are provided at the end of this review.

In this study, we have proposed a rather simple approach to achieving graphene oxide/polyimide (GO/PI) composite films using pre-in situ polymerization. The mechanical, electrical, and carbonization properties of the films were significantly enhanced in the presence of GO. With an addition of 1.0 wt% GO, the tensile strength and Young’s modulus were dramatically increased by 103 and 230% respectively when compared with pure PI film. Besides that, composite films show excellent electrical insulative. Especially, the GO/PI film with 1.0 wt% of GO possesses a high carbonization yield about 64.2% (1000 °C). According to the excellent performance, this approach is believed to afford broad application potential in GO–polymer composite materials.

Multifunctional devices integrated with electrochromism and energy storage or energy production functions are attractive because these devices can be used as an effective approach to address the energy crisis and environmental pollution in society today. In this review, we explain the operation principles of electrochromic energy storage devices including electrochromic supercapacitors, electrochromic batteries, and the photoelectrochromic devices. Furthermore, the material candidates and structure types of these multifunctional devices are discussed in detail. The major challenges of these devices along with a further outlook are highlighted at the end.

In this work, CoMoO4@NiMoO4·xH2O core-shell heterostructure electrode is directly grown on carbon fabric (CF) via a feasible hydrothermal procedure with CoMoO4 nanowires (NWs) as the core and NiMoO4 nanosheets (NSs) as the shell. This core-shell heterostructure could provide fast ion and electron transfer, a large number of active sites, and good strain accommodation. As a result, the CoMoO4@NiMoO4·xH2O electrode yields high-capacitance performance with a high specific capacitance of 1582 F g−1, good cycling stability with the capacitance retention of 97.1% after 3000 cycles and good rate capability. The electrode also shows excellent mechanical flexibility. Also, a flexible Fe2O3 nanorods/CF electrode with enhanced electrochemical performance was prepared. A solid-state asymmetric supercapacitor device is successfully fabricated by using flexible CoMoO4@NiMoO4·xH2O as the positive electrode and Fe2O3 as the negative electrode. The asymmetric supercapacitor with a maximum voltage of 1.6 V demonstrates high specific energy (41.8 Wh kg−1 at 700 W kg−1), high power density (12000 W kg−1 at 26.7 Wh kg−1), and excellent cycle ability with the capacitance retention of 89.3% after 5000 cycles (at the current density of 3A g−1).

Electroactive conducting copolymers of aniline (ANI) and diphenylamine (DPA) are prepared on indium tin oxide (ITO) surface from 1 mol/L H2SO4 aqueous solution with different feed ratios of ANI to DPA by using a potentiostatic method. FTIR spectra and SEM measurements are used to confirm the formation of copolymers. Due to the combination of the N,N′-diphenyl benzidine and aniline units in the molecular chain, the copolymer films exhibit improved electrochemical and electrochromic properties, compared to PANI and PDPA. The copolymer [marked as P(ANI9-co-DPA1)] film prepared at a ratio of 9:1 (ANI/DPA) exhibits novel transmittance modulation both in visible and near-infrared (NIR) region between −0.8 V and 0.8 V (52% and 67% respectively) and fast response time (3.6 s for coloration and 2.3 s for bleaching at 600 nm). An electrochromic device (ECD) based on P(ANI9-co-DPA1) and PEDOT:PSS is also fabricated and shows a multicolor electrochromic performance, with a good optical contrast (29% in visible region and 40% in NIR region), acceptable response time (8.3 s for coloration and 7.5 s for bleaching at 600 nm) and long-term stability. Clear color changes from transparent (−0.8 V), bright green (0 V), seagreen (0.4 V) to dark slate gray (0.8 V) are demonstrated.

Macroporous materials with three dimensional pores and channels are anticipated to exhibit improved performance in numerous applications such as photonic band gap crystals, battery electrodes and gas sensors due to their special structure. In this work, macroporous Cu2O thin films were prepared by template-assisted electrodeposition method. The mechanism of electrodeposition infiltrating procedures indicated that the target architectures can basically maintain its original shape, and the fabrication of spherical-porous shaped Cu2O controlled by crystalline structures is firstly studied systematically. The morphology of macroporous material along the (1 1 1) direction demonstrated that the target architecture can copy both the crystalline structures and the colloidal crystal template. Moreover, models are set up to discuss the evolution of the morphology (the shapes of the pore mouths and pore walls), which indicated that the pore mouths and pore walls were deeply influenced by the deposition depth.

Three-dimensional ordered macroporous (3DOM) materials are anticipated to exhibit improved performance in lots of applications due to their special structure. This paper presents the formation mechanism of 3DOM structure during the removal process of templates, which has not been systematically studied yet. Using polymer colloidal crystal template, 3DOM metallic materials were prepared by electrochemical deposition and dissolution. The results indicate that windows in inverse opals are formed because of the associated breaking of thin wall materials. There seems to be a critical thickness for the same wall materials. The existence of windows improved the formation of 3DOM structures during the removal process of templates.

Because vanadium pentoxide (V2O5) is the only oxide that shows both anodic and cathodic coloration electrochromism, the reversible lithium ion insertion/extraction processes in V2O5 lead to not only reversible optical parameter changes but also multicolor changes for esthetics. Because of the outstanding electrochemical properties of V2O5 nanofibers, they show great potential to enhance V2O5 electrochromism. However, the development and practical application of V2O5 nanofibers are still lacking, because traditional preparation approaches have several drawbacks, such as multiple processing steps, unsatisfactory electrical contact with the substrate, expensive equipment and rigorous experimental conditions. Herein, we first report a novel and convenient strategy to prepare grass-like nanofiber-stacked V2O5 films by a simple annealing treatment of an amorphous, three-dimensionally ordered macroporous vanadia film. The V2O5 nanofiber grassland exhibits promising transmittance modulation, fast switching responses and high color contrast because of the outstanding electrochemical properties of V2O5 nanofibers as well as the high Li-ion diffusion coefficients and good electrical contact with the substrate. Moreover, the morphology transformation mechanism is investigated in detail.

Ni-Zn ferrite powders were synthesized by self-propagating high temperature synthesis (SHS) method. X-ray diffraction, TEM and vibrating sample magnetometry (VSM) were used to characterize the phase composition, microstructure and magnetic properties of the combustion products. The effect of the combustion temperature (Tc), the major parameter of the SHS process, on particle size, phase composition and magnetic properties of the products was also studied. The results showed that particle size grew with the increasing combustion temperature. The maximum saturation magnetization,Ms, increased with combustion temperature indicating the growth of grain size and high degree of ferritization, while residual magnetization,Mr, and coercive force,Hc, decreased. Compared with other methods, Ni0.35Zn0.65Fe2O4 ferrite powders with improved magnetic properties can be obtained by SHS at 1000°C.