Prussian Blue Films Research Articles

Interface engineering of SnO2 to enhance the cycle stability of WO3 and Prussian blue for complementary electrochromic smart windows and energy storage

The interface mismatch between electrochromic materials and conductive layer seriously affects the cycle stability of electrochromic smart windows (ESW). However, it is difficult to improve the interface matching at the same time because of the different physical and chemical properties of anode and cathode materials. In this work, SnO2 nanosheets are used as the interface modification layer between electrochromic materials and conductive layer. SnO2 interface engineering significantly can improve the cycle stability of WO3 film and Prussian blue (PB) film. The WO3/SnO2-PB/SnO2 complementary ESW exhibits a high optical modulation of 60.2 % at 633 nm, fast response time (bleached/colored time = 8.5/2.5 s), and coloration efficiency of 91.7 cm2 C−1. The WO3/SnO2-PB/SnO2 device can still maintain an optical modulation of 45.2 % after 2000 cycles, suggesting excellent long cycle stability. And the device shows the energy storage of 5.06 mF cm−2 at 0.1 mA cm−2, which can improve energy efficiency. The excellent electrochromic properties and energy storage suggests that SnO2 interface engineering has a good application prospect in multi-functional ESW with excellent cycle stability.

Two comparative novel facile synthesis of Prussian blue/polyaniline bilayer films for supercapacitor electrode

A nanocomposite films of Prussian Blue/Polyaniline were prepared on ITO without binder, by two procedures: The first by forming thin multi layers of films of Prussian blue and Polyaniline alternatively, up to seven utilizing “layer by layer” technique. To prepare another film, a thick layer of Prussian Yellow was made under a Polyaniline layer with almost the same load of materials.PB successive layers were fabricated by dipping the ITO in a mixture of (Fe (NO3)3 + K3Fe(CN)6) solution, for a few minutes. next Pani layers were overlayed by electropolymerizing of aniline solution on the ITO/PY electrode. PY instantly was reduced by aniline as soon as dipped in solution, resulting in a nano Prussian Blue film on ITO.Uv-vis and FT-IR spectroscopy were used to characterize the fabricated films. AFM and SEM were utilized to study its morphology. The capacitive behavior of the two types of films was studied utilizing CVs and GCD techniques. The resistance of the electrode/electrolyte interface was studied by EIS. The electrochemical analysis confirmed that the multi-layer by layer thin film has much-improved specific capacitance of 255.6 F/g at 1 A/g current density and superior stability of 96.4 % of its initial value after 500 cycles.

Self-powered sandwich-type dual-mode sensor built on open bipolar electrode

Here, we developed a self-powered bipolar electrode (SP-BPE) based dual-mode sensor with electrochromic (EC) and photoelectrochemical (PEC) techniques for the visualized and sensitive detection of bisphenol A (BPA). An open BPE with the molecularly imprinted polymers (MIPs) modified electron injection area and the Prussian blue (PB) coated electrochromic area was fabricated on an indium tin oxide (ITO) glass. A kind of Zr-based metal-organic framework (UiO-66) coated TiO2 heterojunction (TiO2@UiO-66) was used for aptamer (Apt) immobilization and electron generation. BPA was selectively accumulated by MIPs, and subsequently recognized TiO2@UiO-66-Apt quantitatively, resulting in the formation of MIPs/BPA/Apt-TiO2@UiO-66 “sandwich” structure. Under UV-light, electrons were generated from the captured TiO2@UiO-66. For EC visualization measurements, electrons were injected into the PB film, causing a color change without an external power source. The extent of color change was proportional to the number of generated electrons, which correlated with the amount of captured BPA within a concentration range of 10−6–10−11 M. This allowed for the semi-quantification of BPA by naked eyes. For PEC detection, the BPE was used as the working electrode in a three-electrode system. The generated photocurrents signals could be digitally output for BPA with the concentrations ranging from 10−5 to 10−11 M. The SP-BPE sensors showed low background signal, improved selectivity and anti-interference abilities, and have demonstrated excellent performance in quantitative BPA analysis in water samples. They are particularly useful in scenarios where traditional power sources are limited or unavailable, and they offer opportunities for sustainable and environmentally friendly target detection.

Square-wave voltammetric evaluation of electrochemical constants: Comparative study with other techniques

Square-wave voltammetry was employed for evaluation of electrochemical rate constants for soluble hexacyanoferrate ions as well as for iron hexacyanoferrate (Prussian blue) and nickel hexacyanoferrate immobilized on carbon electrodes. Modelling of square-wave response of immobilized species with assumption of Nernstian behavior, the dimensionless net current peak splitting occurs. The peak value decreases with the rise of square-wave amplitude Esw and splits around the common value of 50 mV. For a quasireversible behavior, the dimensionless net peak current has an extremum depending on both frequency and Esw. At 40 mV, the frequency in the extremum almost coincides with the surface electrochemical rate constant ksur. For practical confirmation, the Prussian blue film was studied at different frequencies (Esw = 50 mV). At lower values, the reaction is relatively fast and net peak current splitting occurs. At higher values, the net response reaches its maximum allowing to evaluate the surface electrochemical rate constant. A comparative investigations of electrode kinetics (for both surface and heterogeneous electrochemical constant) by different electrochemical methods proved the advantages of square-wave pulse technique. In contrast to cyclic voltammetry and electrochemical impedance spectroscopy, the square-wave voltammetry has lower variation of estimated parameters, relatively simple calculations, uncomplicated simulation of different mechanisms.

A Highly Efficient and Energy Saving Electrochromic Platform for Adaptive Visible and Near-Infrared Light Modulation

Dual-band electrochromic devices (DBEDs) with reversible optical properties in visible (VIS) and near-infrared (NIR) spectral ranges are highly desirable for intelligent technologies (e.g. electrochromic smart windows, adaptive and military camouflages). However, most available DBEDs only have two optical states - namely the bleached and colored states, and efforts are committed to increasing the optical modulation between them, while durability of cycling is rarely reported. Herein, we report a novel multicolored rocking-chair DBED based on Prussian blue (PB) thin films as electrochromic layers and a conductive carbon cloth (CC) frame as the counter electrode. During the electrochromic process, cations from the electrolyte migrate back and forth between PB and CC, and electrolysis of aqueous electrolyte can be effectively avoided to extend device longevity. The PB-CC DBED exhibits superior dual-band electrochromic performance with a wide range of switchable colors, including transparent, blue, green and yellow, large optical modulation in VIS-NIR ranges, fast response speed, high coloration efficiency and long-term durability. Based on the diverse color change in the VIS range and thermal control in the NIR range, the camouflage ability of the device is also described. Finally, an adaptive optical modulation platform is demonstrated, obtained by connecting the PB-CC device to a voltage-controlled circuit module to realize intelligent and autonomous color switching of the device.

Probing the Electronic Structure of Prussian Blue and Analog Films by Photoemission and Electron Energy Loss Spectroscopies.

X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS) were employed to characterize the electronic properties of Prussian blue (PB) and its analogs when electrodeposited over metal-decorated carbon nanotubes (CNTs). Through an investigation of the influence of carbon nanotubes (CNTs) and preparation conditions on the electronic structure, valuable insights were obtained regarding their effects on electrochemical properties. XPS analysis enabled the probing of the chemical composition and oxidation states of the film materials, unveiling synthesis-driven variations in their electronic properties. REELS provided information on energy loss and electronic transitions, enabling further characterization of the changes in the electronic structure induced by different preparation methods. Such findings emphasize the importance of surface characterization to understand how the unique electronic properties of such materials can be harnessed to enhance their performance and functionality.

Electrofluorochromism based on the valence change of europium complexes in electrochemical devices with Prussian blue as the counter electrode.

The electrofluorochromism of Eu complexes based on the valence change between Eu3+ and Eu2+ is demonstrated in a two-electrode electrochemical device consisting of Prussian blue (PB) as the counter electrode. This study aims to improve the electrofluorochromic (EFC) performance of luminescence switching between Eu3+ and Eu2+ by enhancing the electrochemical reactivity of the EFC device. By introducing a PB film as a counter electrode in a two-electrode device, the redox reaction of Eu3+/2+ is promoted because of charge compensation by the counter PB film. The increase in the reaction charge enables faster changes in the photoluminescence from Eu3+ to Eu2+ and an increase in the blue luminescence intensity from the Eu2+ state. This approach achieves a lowered driving voltage, accelerates the electrochemical redox reaction of the Eu complex, and enhances the reversibility of the valence change of the Eu ion.

High-performance electrochromic device based on poly acrylamide gel polymer electrolyte containing hypromellose

Cellulose is one of the most widely distributed and abundant natural polymer material. Hypromellose (HPMC), a cellulose derivative, has received much attention in recent years in the field of electrolytes because of its biodegradability, high transparency, excellent water solubility and biocompatibility. In this work, poly acrylamide (PAM)-based hydrogel electrolytes with high ionic conductivity (5.3 × 10−2 S cm−1) and high transmittance (95.8% at 672 nm) were prepared by thermocuring AM monomer containing a certain amount of HPMC. We assembled an electrochromic device (ECD) based on this gel polymer electrolyte (GPE) with Prussian blue (PB) film and WO3·xH2O film. The ECD enables color switching between colorless and blue states. The optical modulation at 672 nm is 73.2% and the coloration efficiency is 154.7 cm2⋅C−1. The coloration time and bleaching time are 2.5 and 3.1 s, respectively. In addition, the optical modulation of the ECD remains 93.7% of its initial value after 1,000 cycles, demonstrating a good cycling stability of the ECD, which should be attributed to the existence of large number of hydrogen bonds between PAM and HPMC.

Boosting the Self-Recharging of Polypyrrole/Prussian Blue Electrochromic Device by Potential Difference-Driven Alternative Redox.

Energy-storage electrochromic (EC) devices are a kind of recently developed device integrating energy-saving and energy-storage functions. To minimize energy consumption, a self-rechargeable energy-storage EC device with fast recovery speed is highly desired. Herein, a polypyrrole (PPy)/Prussian blue (PB) double-layer film with a potential difference is initially constructed and fabricated into a fast-recovery self-rechargeable EC device. Due to the existence of potential difference, the reduced PPy can be oxidized by PB, and subsequently Prussian white (the reduced state of PB) can be oxidized by O2 dissolved in electrolyte. Thus, the self-coloration/self-recharging process can be boosted by an alternative redox occurring in the solid/solid/liquid interfaces of PPy/PB/dissolved O2 instead of common solid/liquid interfaces or solutions. After self-recharging for 1 h, 65.0% of the open-circuit voltage and 45.2% of the total capacity can be recovered. Simultaneously, the synergy effect in this PPy and PB system enables a large optical modulation of 63.3% at 800 nm, a high open-circuit voltage of 1.20 V, and a large initial specific capacity of 87.8 mA·h·g-1 at 1.0 A·g-1. The design of double-layer film with a potential difference for boosting the self-coloration/self-recharging process of EC devices provides a new strategy for next-generation self-powered energy-storage EC devices.

Long-life Inorganic Electrochromic Device Based on WO3 and PB Films with Fast Switching Respond

Complementary electrochromic devices were fabricated by using tungsten trioxide (WO3) film as working electrode, Prussian blue (PB) film as counter electrode and 0.1 M lithium perchlorate in propylene carbonate as electrolyte. The XRD result presents that WO3 and PB films are amorphous, which is favourable for a fast ion intercalation-deintercalation process. The device was tested under potentiostatic control using ±1.3 V steps, and changed its color between blue and colorless. It has a fast-switching respond (about 1.5 s for colouring and 2 s for bleaching) and could withstand 100,000 cycles with little change in its optical contrast.

Waterproof, high-contrast and fast response gasochromic thin film composed of Prussian blue, polyvinyl alcohol, 3-glycidoxypropyltrimethoxysilane and catalytic nanoparticles

Here we synthesize a waterproof cross-linked gasochromic thin film obtained by incorporating Prussian blue nanoparticles, polyvinyl alcohol, crosslink agent: 3-glycidoxypropyltrimethoxysilane and catalytic platinum nanoparticles, applied by a single coating and heat process onto a substrate. The cross-linked polyvinyl alcohol-Prussian blue (PVA-PB) films reveal an excellent hydrophilic character. The contrast ratio at 700 nm reaches 87.2. The cycle stability exceeds 200 cycles. The switching time from deep blue to transparency took 14.3 s for bleaching and 600 s for darkening. Surface electron microscopy, electrochemical analysis and Fourier-transform IR spectroscopy were used to investigate a series of waterproof Prussian blue films. The results showed the redox mechanism between polymer matrix, chrome and catalytic nanoparticles.

Controlled hydrothermal synthesis of Prussian Blue films with multicolor electrochromic behaviors

Prussian blue films were fabricated on fluorine doped tin dioxide glass by a hydrothermal technique through modulation of reactants, reaction temperature and reaction duration. Reagents and hydrothermal temperature were found to largely affect the color, structure, and property of PB films. When the dosage of hydrobromic acid was above 0.9 mL and the hydrothermal temperature was above 120 °C, the reagents could react completely. A plausible formation mechanism of PB was proposed based on experimental results. Hydrobromic acid acts as both a reducing agent and a strong acid in the hydrothermal process. The PB film obtained in presence of 0.9 mL HBr by a hydrothermal treatment at 180 °C for 1h shows a good cycle stability. The PB devices with “sandwich” structure were assembled and exhibited multicolor electrochromic behaviors, and could change the color from initial blue to transparent and green, reversibly, under different power supplies. The coloration efficiency values of PB device were ca. 50.1 and 27.6 cm2/C, corresponding to the process from PB to PW and PG, respectively.

Improving the electrochromic performance of prussian blue (PB) thin films by using an innovative electrothermophoresis method

Improving the electrochromic performance of prussian blue (PB) thin films by using an innovative electrothermophoresis method

Variable-Tint Electrochromic Supercapacitor with a Benzyl Hexenyl Viologen-Prussian Blue Architecture and Ultralong Cycling Life

A highly efficient, separator-free, low-cost, dual-function electrochromic supercapacitor (ESC) with a benzyl hexenyl viologen (BHV) based gel film and a Prussian blue (PB) film as the anode and cathode, respectively, has been fabricated. The BHV//PB ESC operates over a wide potential window of 2 V and offers a specific capacitance of 67 F g–1 with energy and power density maxima of 37.2 Wh kg–1 and 6.7 kW kg–1, respectively. Simultaneously, during the charging process, the ESC undergoes a reversible and uniform color transition from pale blue to a deep rich purple hue, corresponding to a transmission modulation of ∼68% at 550 nm and an integrated visible light modulation of ∼50%, superior to those of most ESCs in the literature. The ESC offers a visually perceptible level of charging through the variable tints it acquires during charging or discharging. The ESC also sustains high external temperatures with ease, as even at 60 °C, the contrast is ∼80% at 550 nm, making it suitable for hot weather conditions. The ESC delivers an ultralong cycling life, for it does not undergo any major optical modulation loss even after 5000+ color–bleach cycles and retains 85% of its initial capacitance after 5000 charge–discharge cycles. The evolution of the charge–discharge mechanism from being predominantly ionic diffusion controlled to largely surface reaction controlled with scan rate is also demonstrated. The remarkable chemical and electrochemical cycling stability, the very high optical contrast, the reasonably fast switching kinetics, and the color purity of the bleached and colored states achieved over a geometric area of 4 × 3 cm2 are clear indicators of the potential the BHV//PB ESC has for practical deployment as a window that not only provides visual/thermal comfort but also has stored-up energy to power any external electronic device.

Facile Hydrothermal Synthesis of Prussian Blue Films Using Hydrobromic Acid and their Electrochromic Properties

Prussian Blue (PB) films were directly grown on FTO glass by a hydrothermal method only using potassium ferricyanide and hydrobromic acid as raw reagents. Hydrobromic acid plays the role of both providing acidic conditions and as a reducing agent which improves the atomic utilization of the raw materials. The as-prepared PB devices exhibited multicolor electrochromic properties: Blue, green and transparent states, reversibly. The maximum optical modulations of PB device could reach the range of 47.7%. The PB films also have a fast coloration/bleaching time of 1.9/1.3[Formula: see text]s, respectively. This study provided a novel method for preparing PB films by a facile hydrothermal method.

A hydrogel electrolyte based on hydroxypropyl methylcellulose modified polyacrylamine for efficient electrochromic energy storage devices

The electrolyte play a crucial role for the efficient operation of electrochemical devices. In this work, we developed a new hydrogel electrolyte based on hydroxypropyl methylcellulose modified polyacrylamine framework for electrochromic energy storage devices. By using the present electrolyte, the sandwich electrochemical devices based on complementary electrodes of prussian blue (PB) and tungsten trioxide (WO3) thin films exhibited reversible electrochromic switch between colorless and dark blue, with large optical contrast over 80 %, short response time below 2 s, high coloration efficiency over 168 cm2/C, and good cycle stability. Moreover, the devices showed good energy storage ability with an area capacitance of 6.32 mAh/m2 at a current density of 0.02 mA/cm2. The dual functional electrochemical devices showed potential application in energy saving smart windows.

Self-Powered Flexible Multicolor Electrochromic Devices for Information Displays.

The development of self-powered flexible multicolor electrochromic (EC) systems that could switch different color without an external power supply has remained extremely challenging. Here, a new trilayer film structure for achieving self-powered flexible multicolor EC displays based on self-charging/discharging mechanism is proposed, which is simply assembled by sandwiching an ionic gel film between 2 cathodic nickel hexacyanoferrate (NiHCF) and Prussian blue (PB) nanoparticle films on indium tin oxide substrates. The display exhibits independent self-powered color switching of NiHCF and PB films with fast responsive time and high reversibility by selectively connecting the Al wire as anodes with the 2 EC films. Multicolor switching is thus achieved through a color overlay effect by superimposing the 2 EC films, including green, blue, yellow, and colorless. The bleaching/coloration process of the displays is driven by the discharging/self-charging mechanism for NiHCF and PB films, respectively, ensuring the self-powered color switching of the displays reversibly without an external power supply. It is further demonstrated that patterns can be easily created in the self-powered EC displays by the spray-coating method, allowing multicolor changing to convey specific information. Moreover, a self-powered ionic writing board is demonstrated based on the self-powered EC displays that can be repeatedly written freehand without the need of an external power source. We believe that the design concept may provide new insights into the development of self-powered flexible multicolor EC displays with self-recovered energy for widespread applications.

Electrochemical Preparation of Prussian Blue Thin Films and Investigation of Their Photoelectric Properties

Electrochemical Preparation of Prussian Blue Thin Films and Investigation of Their Photoelectric Properties

Galvanic-driven deposition of large-area Prussian blue films for flexible battery-type electrochromic devices

A flexible Prussian blue electrode has been finely fabricated by galvanic-driven deposition for building mechanically stable Zn/PB flexible battery-type electrochromic devices.

An Amperometric Glucose Biosensor Composed of Prussian Blue, Nafion, and Glucose Oxidase Studied by Flow Injection Analysis

The construction and characterization of a glucose biosensor has been implemented in an instrumental chemical analysis course to provide students experience with chemical sensing, electroanalytical methods, and flow injection analysis (FIA). The glucose biosensor was assembled on a glassy carbon electrode by depositing a layer of Prussian blue (PB) electrocatalyst followed by a layer of glucose oxidase (GOx) immobilized in a Nafion film. GOx catalyzed the oxidation of glucose in the presence of dissolved oxygen to yield gluconic acid and hydrogen peroxide. The hydrogen peroxide produced was then electrocatalytically reduced at the PB film with a mild applied potential. The measured cathodic current provided the analytical signal for the glucose biosensor, which was applied to the quantification of glucose levels in soft drinks using FIA techniques. This experiment exposes students to several electroanalytical methods, including amperometry, cyclic voltammetry, and chronocoulometry, as well as methods that are used to measure biosensor response, deposit the PB film, measure the PB film coverage, and examine its electrocatalytic properties. In addition, students gain experience with FIA and the application of an enzyme-based biosensor.