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Inorganic electrochromic materials are promising for applications in color-based chromogenic technologies. Limited color control in these materials has, however, hitherto hampered their applications. Here, we show that multicolored nickel oxide (NiO) films can be obtained due to the combined effect of the intrinsic color of NiO and the structural color of the inverse opal structures by tailoring anodic oxide NiO films, exhibiting an absorption tail in the visible region into three-dimensional ordered macroporous inverse opal photonic bandgap structures. Various colors were achieved by the synergistic mechanism of structural and electrochromic coloration, thus realizing a wide spectrum of blue, green, yellow, orange, and brown colors depending on pore size, wall thickness, and viewing angle. Importantly, it is shown that the depth of color can be varied by applying an external potential. The electrochromic coloring of the inverse opal NiO films is found to be very different from the typical optical switching of non-structural NiO films. Thus, our work brings insights into the development of inorganic colored electrochromic materials. [ABSTRACT FROM AUTHOR]

Localized surface plasmon resonance (LSPR) is attractive to fabricate visible (VIS) and near‐infrared (NIR) dual‐band electrochromic materials. However, the introduction of the LSPR effect in the available dual‐band electrochromic materials can only be manifested to the spectral enhancement in the NIR region, and difficult issues of electrochromic materials such as low coloration efficiency and unsatisfactory long‐term cycling durability still remain. Here, a dual‐band electrochromic thin film consisting of a 2D ordered macroporous (2DOM) Au LSPR layer and a poly(3,4‐(2,2‐dimethylpropylenedioxy)thiophene) (PProDot‐Me2) electrochromic layer is presented, where LSPR and electrochromism interact in a complementary fashion. The 2DOM Au exhibits LSPR effect at wavelengths of 550 and 1700 nm, leading to a unique electrochromic performance improvement of the film in both of the VIS and NIR spectral regions. Large optical modulation, rapid switching speed, high coloration efficiency, and long‐term durability are achieved due to the collective effect of the near‐field enhancement of the 2DOM Au and the reduced bandgap of PProDot‐Me2. These advantages can be well retained in the dual‐band electrochromic device using the 2DOM Au/PProDot‐Me2 films as the electrochromic layers. This work provides new ideas for designing LSPR‐based devices, especially dual‐band electrochromic materials and devices, both experimentally and theoretically. [ABSTRACT FROM AUTHOR]

The high-performance bi-functional electrochromic supercapacitor constitutes the critical technology for intelligent energy conversion and storage. Facilitating ion/electron transport and intercalation/deintercalation by rational design of the highly porous structure with a large specific surface area is one of the most effective strategies to promote its electrochemical redox reaction. However, difficult issues such as unsatisfactory energy storage due to simple porous structures and severe performance degradation during long-term electrochemical cycles still remain. Inspired by the natural geotexture of forests, a novel Ni/Co-based layered double hydroxide (Ni/Co-LDH) derived from the metal–organic framework grown on ZnO nanotubes on transparent conducting substrates with diverse porous structures is proposed to simulate the "rock-soil-tree-leaf" system. Excellent transmittance modulation, switching speed, specific capacity and durability are realized due to the large specific surface area of the three-dimensional network structured ZnO@Ni/Co-LDH, enhanced OH− capture ability of ZnO, improved electrochemical activity by Ni/Co incorporation and its mixed charge storage behavior. Remarkable electrochromic and energy storage performance of the ZnO@Ni/Co-LDH device is also demonstrated. It serves as an intelligent energy conversion and storage platform to realize automatic optical switching by solar energy collection and charge storage/release. The new insights will pave the way for next-generation intelligent technologies towards a sustainable and liveable future life. [ABSTRACT FROM AUTHOR]

Anodically-coloring nickel oxide, Coloration mechanism, Electrochromism, Thin film Keywords: Anodically-coloring nickel oxide; Coloration mechanism; Electrochromism; Thin film EN Anodically-coloring nickel oxide Coloration mechanism Electrochromism Thin film 1 1 1 04/14/22 20220411 NES 220411 B The Cover Feature b shows Cl SP - sp and Li SP + sp ions adsorb onto the surface of nickel oxide and are accumulated upon extended electrochromic cycling in an electrolyte of 1 M LiClO SB 4 sb -PC. Cover Feature: Cation-/Anion-Based Physicochemical Mechanisms for Anodically Coloring Electrochromic Nickel Oxide Thin Films (ChemElectroChem 7/2022). [Extracted from the article]

The rapidly expanding field of intelligent ion‐based devices has increased interest in the use of anodically‐coloring electrochromic nickel oxide thin films. The degradation and coloration mechanisms of nickel oxide, especially in Li+‐based electrolytes, are yet to be well understood. Herein we demonstrate that high potentials have a positive effect on the electrochromic performance of nickel oxide thin films. Our studies show that Cl− ions involved in the electrochromic process have been accumulated on the surface of the films upon extended electrochemical cycling, as confirmed by the X‐ray Photoelectron Spectroscopy. X‐ray Absorption Spectroscopy results indicate that the formation of Ni−Cl bonds influence the structural distortion and that the hybridization between Ni 3d and O 2p orbitals has been enhanced. Density functional theory calculations provide further insights for the band structures and how they change when Li+ and Cl− are adsorbed. Our results have revealed the underlying physical and chemical origins associated with the coloration mechanism and the degradation of nickel oxide thin films and highlighted the key role of Cl−. These new understandings will advance the development of superior electrochromic materials and the designing of efficient and durable electrochromic devices, both experimentally and theoretically. [ABSTRACT FROM AUTHOR]

Electrochromism has attracted wide attention as futuristic adaptive camouflage technologies due to its reversible and sustainable optical modulation with low energy consumption. However, limited color control of the electrochromic materials has hampered its applications. Inspired by the remarkable dynamic camouflage capabilities of cephalopods, polyaniline (PANI) and polystyrene‐block‐poly (2‐vinyl pyridine) (PS‐b‐P2VP) thin films are integrated to simulate chromatophores and iridophores in the skin of cephalopods, respectively. Herein, it is demonstrated that the adaptive lamellar PANI/PS‐b‐P2VP thin film exhibits a wide range of color control, switchable vivid coloration, and excellent durability. It serves as an ideal multicolored electrochromic platform due to the combined effect of electrochromism from PANI and structural coloration from PS‐b‐P2VP. Unambiguous evidence shows that optical properties of the PANI/PS‐b‐P2VP thin film are related to the thickness of each layer and nanostructure of PANI, pronounced color changes mainly depend on electronic states of PANI and transition of hydrated SO42− ions between PANI and P2VP. The coloration mechanism is discussed using quantitative analysis via RGB color specification and optical transmittance and reflectance simulations. The new insights will advance the design of reflection‐contributed superior multicolored electrochromic materials, and have great potential in the fields of displays and camouflage. [ABSTRACT FROM AUTHOR]

The popularity of intelligent electronic products demands suitable smart electrodes with high specific capacitance, superior durability, and intrinsic safety. Herein, a bifunctional titanium dioxide (TiO2) electrode with electrochromic energy storage in the Zn-ion aqueous electrolyte was demonstrated. The color of the electrode can be changed according to its charging state by Zn2+ intercalation/de-intercalation, to realize the noticeable judgment and prediction of the energy contained. Direct growth of TiO2 by the hydrothermal method effectively increases the bonding force between the active TiO2 material and the substrate. Electrochemical results show that the TiO2 electrode has high specific capacitance of 139.8 mF·cm−2 at 1.5 mA·cm−2, and retains 93% of the initial areal specific capacitance after 100 CV cycles. In addition, it exhibits high transmittance contrast of 45% at a wavelength of 980 nm in the near-infrared region, short bleaching time (6.5 s) and coloration time (18.0 s) at an alternating potential between 0 and − 1.1 V. These superior electrochemical and electrochromic performances can be attributed to the fast Zn2+ diffusion facilitated by the porous structure and short ion diffusion distance of the TiO2 electrode. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is the efficiency-determining half-reaction process of high-demand, electricity-driven water splitting due to its sluggish four-electron transfer reaction. Tremendous effects on developing OER catalysts with high activity and strong acid-tolerance at high oxidation potentials have been made for proton-conducting polymer electrolyte membrane water electrolysis (PEMWE), which is one of the most promising future hydrogen-fuel-generating technologies. This review presents recent progress in understanding OER mechanisms in PEMWE, including the adsorbate evolution mechanism (AEM) and the lattice-oxygen-mediated mechanism (LOM). We further summarize the latest strategies to improve catalytic performance, such as surface/interface modification, catalytic site coordination construction, and electronic structure regulation of catalytic centers. Finally, challenges and prospective solutions for improving OER performance are proposed. [ABSTRACT FROM AUTHOR]

Electrochromic windows and glass facades are able to impart energy efficiency jointly with indoor comfort and convenience. Long-term durability is essential for practical implementation of this technology and has recently attracted broad interest. Here we show that a simple potentiostatic pretreatment of sputter-deposited thin films of amorphous WO3―the most widely studied electrochromic material―can yield unprecedented durability for charge exchange and optical modulation under harsh electrochemical cycling in a Li-ion-conducting electrolyte and effectively evades harmful trapping of Li. The pretreatment consisted of applying a voltage of 6.0 V vs. Li/Li+ for several hours to a film backed by a transparent conducting In2O3:Sn layer. Associated compositional and structural modifications were probed by several techniques, and improved durability was associated with elemental intermixing at the WO3/ITO and ITO/glass boundaries as well as with carbonaceous solid-electrolyte interfacial layers on the WO3 films. Our work provides important new insights into long-term durability of ion-exchange-based devices. [ABSTRACT FROM AUTHOR]

Ni oxide thin films are widely used in electrochromic (EC) devices with variable throughput of visible light and solar energy. However, the mechanisms underlying the optical modulation – and its degradation under extended operation and subsequent rejuvenation – are poorly understood especially for Li+‐conducting electrolytes. Here, we report a comprehensive study of the EC properties of sputter‐deposited Ni oxide films immersed in an electrolyte of LiClO4 in propylene carbonate. Cyclic voltammetry and optical transmittance measurements were used to document degradation and subsequent potentiostatic rejuvenation. X‐ray diffraction did not show evidence for accompanying changes in crystallinity, whereas vibrational spectroscopy indicated that degraded films had carbonaceous surface layers. Time‐of‐flight elastic recoil detection analysis demonstrated that both Li+ and Cl‐based ions participate in the electrochromism and its degradation and rejuvenation. A major result was that degradation is associated with a reduced difference in the concentrations of Li+ and Cl‐based ions in the nickel oxide during extended electrochemical cycling, and rejuvenation of degraded films is achieved by removal of Li+ ions and accumulation of Cl‐based anions to regain their initial concentration difference. Our work provides new insights into the use of ion‐exchange‐based devices incorporating nickel oxide. Bring back to life: Degradation under extended ion insertion/extraction in nickel‐oxide‐based films immersed in a lithium‐based electrolyte is associated with a reduced difference in the concentration of Li+ and Cl‐based ions. Rejuvenation of degraded films can be achieved through the electrochemical removal of Li+ and accumulation of Cl‐based ions to regain their initial concentration difference. This work provides new insights into the use of nickel‐oxide‐based ion‐exchange devices. [ABSTRACT FROM AUTHOR]

A synthetic enzyme-loading nanotube membrane was developed and used in flow-injection analysis (FIA) for the first time. The membrane was based on an anodic alumina oxide (AAO) film that has cylindrical pores with monodisperse nanoscopic diameters, and silica nanotubes (SNTs) were chemically synthesized within the pores of this film through sol–gel chemistry. Horseradish peroxidase (HRP) was immobilized on the inner walls of the SNTs. The fabrication and initial testing of a flow-through membrane reactor design for heterogeneous enzyme reactions were presented and applied to the determination of glucose in real samples. This novel immobilized enzyme membrane reactor possesses some advantages over both open-tubular and packed-bed reactors often used in FIA. The present work shows that the membrane containing SNTs offers considerable potential and new perspectives for the use of such nanomaterials. [ABSTRACT FROM AUTHOR]