Hydrothermal-synthesized mesoporous nickel oxide nanowall arrays with enhanced electrochromic application

An Electrochromic Nickel Phosphate Film for Large-Area Smart Window with Ultra-Large Optical Modulation

Exploring materials with high electrochemical activity is of keen interest for electrochemistry-controlled optical and energy storage devices. However, it remains a great challenge for transition metal oxides to meet this feature due to their low electron conductivity and insufficient reaction sites. Here, we propose a type of transition metal phosphate (NiHPO4·3H2O, NHP) by a facile and scalable electrodeposition method, which can achieve the capability of efficient ion accommodation and injection/extraction for electrochromic energy storage applications. Specifically, the NHP film with an ultra-high transmittance (approach to 100%) achieves a large optical modulation (90.8% at 500 nm), high coloration efficiency (75.4 cm2 C-1 at 500 nm), and a high specific capacity of 47.8 mAh g-1 at 0.4 A g-1. Furthermore, the transformation mechanism of NHP upon electrochemical reaction is systematically elucidated using in situ and ex situ techniques. Ultimately, a large-area electrochromic smart window with 100 cm2 is constructed based on the NHP electrode, displaying superior electrochromic energy storage performance in regulating natural light and storing electrical charges. Our findings may open up new strategies for developing advanced electrochromic energy storage materials and smart windows.

Ligand Incorporating Sequence-dependent ZIF67 Derivatives as Active Material of Supercapacitor: Competition between Ammonia Fluoride and 2-Methylimidazole

The zeolitic imidazolate framework 67 (ZIF67) derivative is a potential active material of supercapacitors (SC), owing to high specific surface area and porosity and possible formation of cobalt compounds. A novel ZIF67 derivative is synthesized using a one-step solution process with cobalt precursor 2-methylimidazole (2-Melm) and ammonia fluoride in our previous work. Due to its facile synthesis and excellent electrocapacitive behavior, it is crucial to understand the competition between ammonia fluoride and 2-Melm on forming derivatives with cobalt ions and to create more efficient ZIF67 derivatives for charge storage. In this work, several ZIF67 derivatives are designed using a one-step solution process with 2-Melm and ammonia fluoride incorporated in different sequences. The reaction durations for a single ligand and two ligands are controlled. The largest capacity of 176.33 mAh/g corresponding to the specific capacitance of 1057.99 F/g is achieved for the ZIF67 derivative electrode prepared by reacting ammonia fluoride and a cobalt precursor for 0.5 h and then incorporating 2-Melm for another 23.5 h of reaction (NM0.5). This derivative composed of highly conductive CoF₂, NiF₂, Co(OH)F, and Ni(OH)F presents high specific surface area and porosity. The relevant SC presents a maximum energy density of 19.5 Wh/kg at 430 W/kg, a capacity retention of 92%, and Coulombic efficiency of 96% in 10000 cycles.

Influence of Sodium Dodecyl Sulfate on the Microstructure and Electrochromic Performance of an Electrodeposited Nickel Oxide Film

Nickel oxide (NiO) films were deposited on indium tin oxide (ITO) coated glass substrates using a potentiostatic electrodeposition method from Ni(NO3)2 aqueous solution containing the surfactant sodium dodecyl sulfate (SDS). The microstructure, morphology, and electrochromic performance of the NiO films were investigated. Our results showed that the addition of SDS inhibited the growth of NiO crystals, tailored the morphology of the films, and favoured their electrochromic performance. The NiO films deposited in the presence of 6mM SDS exhibited excellent electrochromic performance in OH− containing electrolytes (0.1M KOH), with a high optical contrast of over 77% at 550nm, short switching time (5.62s for bleaching and 7.34s for coloration), and enhanced cycling durability.

MOF-derived NiO/Ni architecture encapsulated into N-doped carbon nanotubes for advanced asymmetric supercapacitors

In the second step, the Ni-MOF was transformed into Ni-MOF-600 with low NiO content via calcination under nitrogen protection at 600 °C

Self-supported one-dimensional materials for enhanced electrochromism

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.

Dataset on electro-optically tunable smart-supercapacitors based on oxygen-excess nanograin tungsten oxide thin film

The dataset presented here is related to the research article entitled "Highly Efficient Electro-optically Tunable Smart-supercapacitors Using an Oxygen-excess Nanograin Tungsten Oxide Thin Film" (Akbar et al., 2017) [9] where we have presented a nanograin WO₃ film as a bifunctional electrode for smart supercapacitor devices. In this article we provide additional information concerning nanograin tungsten oxide thin films such as atomic force microscopy, Raman spectroscopy, and X-ray diffraction spectroscopy. Moreover, their electrochemical properties such as cyclic voltammetry, electrochemical supercapacitor properties, and electrochromic properties including coloration efficiency, optical modulation and electrochemical impedance spectroscopy are presented.

NiO Nanoparticle Synthesis Using a Triblock Copolymer: Enhanced Magnetization and High Specific Capacitance of Electrodes Prepared from the Powder

Nickel oxide nanoparticles of diameter ∼21 nm were prepared by a sol-gel method using the triblock copolymer poly(ethylene glycol)-b-(propylene glycol)-b-(ethylene glycol). X-ray photoelectron spectroscopy analysis showed the presence of Ni²⁺ and Ni³⁺ ions in the material. The electrical conductivity of this material was due to small polaron hopping between Ni²⁺ and Ni³⁺ sites. The magnetization shown by these nanoparticles was much higher than that reported in the literature. This is ascribed to the presence of Ni³⁺ ions with uncompensated spin moments. Spin-glass behavior was exhibited by the material at 10.7 K. The electrochemical characterization of electrodes comprising of these NiO nanoparticles using cyclic voltammetric measurements showed a specific capacitance value of 810 F/g, the highest reported for this material. These materials will thus form one of the useful multifunctional systems.

Inkjet-printed all solid-state electrochromic devices based on NiO/WO3 nanoparticle complementary electrodes

Nanostructured thin films are important in the fields of energy conversion and storage. In particular, multi-layered nanostructured films play an important role as a part of the energy system for energy saving applications in buildings. Inkjet printing is a low-cost and attractive technology for patterning and deposition of multi-layered nanostructured materials on various substrates. However, it requires the development of a suitable ink formulation with optimum viscosity, surface tension and evaporation rate for various materials. In this study, a versatile ink formulation was successfully developed to prepare NiO and WO3 nanostructured films with strong adhesion to ITO coated glass using inkjet printing for energy saving electrochromic applications. We achieved a high performance electrochromic electrode, producing porous and continuous electrochromic films without aggregation. The NiO film with 9 printed layers exhibits an optical modulation of 64.2% at 550 nm and a coloration efficiency (CE) of 136.7 cm(2) C(-1). An inkjet-printed complementary all solid-state device was assembled, delivering a larger optical modulation of 75.4% at 633 nm and a higher CE of 131.9 cm(2) C(-1) among all solid-state devices. The enhanced contrast is due to the printed NiO film that not only performs as an ion storage layer, but also as a complementary electrochromic layer.

Improvement on optical modulation and stability of the NiO based electrochromic devices by nanocrystalline modified nanocomb hybrid structure

Among the explored materials for electrochromic devices (ECDs), nickel oxides thin films have been widely applied as an optical anodic layer due to its ability to adjust the optical properties by ion exchange.

Flower-like nickel oxide micro/nanostructures: synthesis and enhanced electrochromic properties

NiO micro/nanoflowers synthesized by hydrothermal treatment followed by calcination exhibit enhanced electrochromic properties.

Potentiostatic reversible photoelectrochromism: an effect appearing in nanoporous TiO2/Ni(OH)2 thin films

In the field of energy saving, finding composite materials with the ability of coloring upon both illumination and change of the applied electrode potential keeps on being an important goal. In this context, chemical bath deposition of Ni(OH)2 into nanoporous TiO2 thin films supported on conducting glass leads to electrodes showing both conventional electrochromic behavior (from colorless to dark brown and vice versa) together with photochromism at constant applied potential. The latter phenomenon, reported here for the first time, is characterized by fast and reversible coloration upon UV illumination. The bleaching kinetics shows first order behavior with respect to the Ni(III) centers in the film, and an order 1.2 with respect to electrons in the TiO2 film. From a more applied point of view, this study opens up the possibility of having two-mode smart windows showing not only conventional electrochromism but also reversible darkening upon illumination.