Electrochromic Properties of Nickel Hexacyanoferrate Thin Films Prepared by a Simple Chemical Deposition Method

In this work a simple chemical bath deposition method was developed and employed for the preparation of Nickel Hexacyanoferrate (NiHCF) films. The films were deposited by successive immersion of the fluorine doped glass substrates (FTO) into acidic aqueous solution of NiCl2 and K4[Fe(CN)6]. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) confirmed that the obtained NiHCF films had crystalline structure. Cycling voltammetry was performed in order to investigate the electrochemical properties of the films. Visible spectra of NiHCF films were recorded in-situ in the both, bleached and colored state. From those spectra were estimated the optical band gaps. The response times of the bleaching and coloring was estimated to an abrupt potential change from -2 V to +2 V and reverse. The coloration efficiency was estimated from the dependence of the optical density on charge density

Non–enzymatic Amperometric Sensor for H2O2 Based on MnCO3 Thin Film Electrodes

The present study describes development of a non–enzymatic amperometric sensor for detection of H2O2 based on MnCO3 thin film electrodes. The film was deposited on electroconductive FTO coated glass substrates using simple chemical bath deposition method. The phase composition of the thin film was confirmed by X-ray diffraction analysis. The electrochemical properties and the sensor sensitivity towards H2O2 were examined using cyclic voltammetry and chronoamperometry in 0.1 M phosphate buffer solution with pH = 7.5. It was revealed that the sensing mechanism is based on electrocatalytic oxidation of H2O2, involving Mn species as redox mediators. According to the results, the best sensor response towards H2O2 was found at E = +0.25 V, with detection limit and sensor sensitivity of 10.0 µM and 2.64 µA cm–2 mM–1 (for the range of 0.09–1.8 mM), respectively, associated with R2 = 0.999. This work is licensed under a Creative Commons Attribution 4.0 International License

Cost Effective Microscale Gas Generation Apparatus

A new method for microscale gas generation is described. The best way of performing this method is as a hands-on experiment. The microscale gas generation apparatus consists of a plastic test tube closed with half-cut pipette bulb and a syringe with a needle. In order to observe the reaction of the generated gas with some reagent, the pipette tubing can be introduced into a second test tube. Using this method, many gases such as carbon dioxide, chlorine, oxygen, hydrogen, ammonia, sulfur dioxide, hydrogen halogenides, hydrogen cyanide, some hydrides and acetylene can be generated. The proposed method for microscale gas generation is safe, simple, cheap and attractive. Keywords: gas generation, hands-on experiments, teaching chemical experiment, microscale experimentatio

Chemical Bath Coating and Characterisation of Electrochromic Manganese(II) Carbonate Thin Films

A chemical bath technique for manganese(II) carbonate thin films deposition on electroconductive FTO – layered glass substrates is described in this report. Homogeneous thin films were obtained from an aqueous solution containing H2NCONH2 and MnCl2. The deposition is performed at temperature of 98 °C. The chemistry background of the process is the hydrolysis of urea [1,2]. Thin films were studied using X-ray diffraction, Profilometry, Cyclic Voltammetry (CV) and UV/VIS spectrophotometry. A combination of electrochemical and optical measurements has revealed electrochromic behaviour. By means of X-ray diffraction measurements the structure, crystallinity and the chemical composition, corresponding to manganese(II) carbonate, have been determined. Thin films thicknesses were determined using Profilometry. Keywords: manganese(II) carbonate, thin films, electrochromic materials, chemical bath deposition method

Energy Efficiency with Electrochromic Prussian Blue Thin Films

Prussian Blue (PB) thin films were prepared by chemical bath deposition onto fluorine doped tin oxide (FTO) coated glass substrates. Elelctrochromic behavior of the films was examined in an electrochromic device (ECD) consisted of home-built glass cell with a 1 mol/dm3 KCl as an electrolyte, PB film as working, and FTO as counter electrodes. These films showed electrochromism changing color from deep blue in as deposited state, to green in oxidized state, and back to blue and transparent (colorless) in reduced state. Visible transmittance spectra of the PB thin films in bleached and colored states were recorded in-situ. Absorption coefficients spectra were calculated using the transmittance spectra. The output integral of the spectral intensity and the integral of the spectral modulation were calculated by taking the solar irradiance spectrum AM 1.5 for a normal illumination on a PB – based ECD, and the absorption coefficients spectra of the PB films in their bleached and colored state

A Simple Chemical Method for Deposition of Electrochromic Cobalt Hexacyanoferrate Thin Films

In this work a simple chemical method for depositing cobalt hexacyanoferrate (CoHCF) films has been developed. The films have been prepared by successive immersion of the fluorine doped glass substrates (FTO) into an acidic aqueous solution of CoCl2 and K4[Fe(CN)6]. The characterization of the films with X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) showed that the films have crystalline structure. The electrochemical properties of the films were characterized by cyclic voltammetry. Obtained films exhibited electrochromism, changing colour reversibly between transparent and brown. Visible transmittance spectra of CoHCF films in their bleached and coloured states were recorded in-situ. Those spectra were used to estimate the optical band gaps. The dependence of the optical density on charge density was examined and used to calculate the colouration efficiency. The response times of the colouring and bleaching to an abrupt potential change from -2 V to +2 V and reverse were also examined. The maximum light intensity modulation ability of the films and saved energy, when the AM 1.5 spectrum is taken as an input, were calculated to be 55% and 243.56 Wm-2, respectively, which makes this films suitable for application in electrochromic devices

Design of Nonenzymatic Amperometric Sensor for H2O2 Based on Electrodes Modified with Nanoscaled MnCO3 Thin Films

The present study is related to the development of nonenzymatic amperometric sensors for detection of hydrogen peroxide (H2O2). The designed sensors are based on manganese(II) carbonate thin film modified electrodes. The films are deposited on electroconductive fluorine doped SnO2-coated glass substrates using chemical bath deposition method. Thin film chemical composition and structural analysis are studied using XRPD and FTIR. The electrochemical properties and sensitivity towards H2O2 are examined using cyclic voltammetry and chronoamperometry. Thin films with three different thicknesses of 75 and 100 nm are used. The electrochemical experiments are carried out in a phosphate buffer solution with c(K2HPO4/KH2PO4) = 0.1 M and pH = 7.5 and wide concentration range of hydrogen peroxide from 0.1 to 25 mM is investigated. The best results are obtained under oxidation potential when using 75 nm MnCO3 thin film and concentrations of H2O2 from 0.1 up to 10 mM. The lowest detection limit was 90 μM and the sensitivity of the sensor was 2.00 μA·cm-2·mM-1. The calibration plot is associated with a linear regression line and coefficient of R2 = 0.99

Electrochromic Properties of Prussian Blue Thin Films Prepared by Chemical Deposition Method

The manifestation of electrochromic phenomena makes Prussian blue (PB) thin films very attractive, especially because they exhibit four-color polyelectrochromicity. In this work PB thin films were prepared by simple and low cost shemical deposition method. The films were deposited onto fluorine doped tin oxide (FTO) coated glass substrates. An electrochromic test device (ECTD) was constructed by using these films as working electrodes, and FTO coated glass as an opposite electrode in aqueous solution of 1 mol/dm3 KCl as supporting electrolyte. The electrochemical properties of the films were characterized by cyclic voltammetry. The obtained films exhibited electrochromism, changing color from deep blue in as deposited state into green, and back to blue and colorless. Visible transmittance spectra of PB films were studied in-situ in as deposited, colored and bleached states. From those spectra, contrast ratio (CR) and the optical band gaps Eg were evaluated. The dependence of the optical density (OD) on charge density was examined and the coloration efficiency (CE) was calculated to be 149.8 cm2C-1. The time response during the film switching between transparent and blue states was also examined

Infrared and Raman Spectra of Magnesium Ammonium Phosphate Hexahydrate (Struvite) and its Isomorphous Analogues. VIII. Spectra of Protiated and Partially Deuterated Magnesium Rubidium Phosphate Hexahydrate and Magnesium Thallium Phosphate Hexahydrate

Abstract The infrared and Raman spectra of magnesium rubidium phosphate hexahydrate MgRbPO 4 · 6H 2 O and magnesium thallium phosphate hexahydrate, MgTlPO 4 · 6H 2 O were recorded at room temperature (RT) and the boiling temperature of liquid nitrogen (LNT). To facilitate their analysis, also recorded were the spectra of partially deuterated analogues with varying content of deuterium. The effects of deuteration and those of lowering the temperature were the basis of the conclusions drawn regarding the origin of the observed bands which were assigned to vibrations which are predominantly localized in the water molecules (four crystallographically different types of such molecules exist in the structures) and those with PO 4 3-character. It was concluded that in some cases coupling of phosphate and water vibrations is likely to take place. The appearance of the infrared spectra in the O-H stretching regions of the infrared spectra is explained as being the result of an extensive overlap of bands due to components of the fundamental stretching modes of the H 2 O units with a possible participation of bands due to second-order transitions. A broad band reminiscent of the B band of the well-known ABC trio characteristic of spectra of substances containing strong hydrogen bonds in their structure was found around 2400 cm -1 in the infrared spectra of the two studied compounds