Fluorine-doped Tin Oxide-coated Glass Research Articles

ZnO Nanorods Aligned in a Vertical Configuration for Targeted Electrochemical Detection of Aniline.

This study demonstrates the synthesis of 1D surface vertically aligned nanorods of ZnO on the fluorine-doped tin oxide-coated glass substrate (ZnO-VANRs/FTOs) synthesized via a chemical route for the targeted electrochemical sensing of aniline. The ZnO-VANRs/FTOs were 1.57 ± 0.03 μm in length with excellent crystallinity and high density (1.52 × 1013 rod no./m2). ZnO-VANRs formation increased surface roughness by 2.4- and 4.7-fold compared to the bare FTOs and seeded FTOs (ZnO-seed/FTOs), respectively. The ZnO-VANRs/FTOs electrodes could increase the effective surface area from 0.154 to 0.384 cm2 with about 86.85% reduction in charge transfer resistance compared to the bare FTOs. The peak current response (at 0.281 V vs Ag/AgCl) of aniline deposition was boosted by 81.52% with the rise in temperature from 15 to 45 °C. The reduction of aniline at ZnO-VANRs/FTOs involved a reversible two-electron diffusion control process with a heterogeneous reaction rate constant (k0) of 1.82 s-1 and a formal potential (E0) of 0.289 V vs Ag/AgCl. The ZnO-VANRs/FTOs electrode showed limits of detection of 0.193 μM (sensitivity 0.198 μA·μM-1·cm-2) and 0.588 μM (sensitivity of 0.065 μA·μM-1·cm-2) between the working ranges of 0-20 and 20-160 μM, respectively. The fabricated sensor was unprecedently selective toward aniline sensing, and p-nitroaniline, chlorobenzene, chlorpyrifos, Cu2+, Pb2+, Ni2+, Cd2+, albumin bovine, Escherichia coli, and ciprofloxacin could not interfere with aniline sensing and its sensitivity. However, the peak current was marginally decayed by 2.63% up to the 6th cycle. Moreover, ZnO-VANRs/FTOs catalyzed the sensing of aniline spiked in the environmental matrices, conforming well to liquid chromatography.

Thermal transport and optical anisotropy in CVD grown large area few-layer MoS2 over an FTO substrate

Atomically thin MoS2 is a promising candidate for its integration into devices due to its strikingly unique electronic, optical, and thermal properties. Here, we report the fabrication of a few-layer MoS2 thin film over a conducting fluorine-doped tin oxide-coated glass substrate via a one-step chemical vapor deposition method. We have quantitatively analyzed the nonlinear temperature-dependent Raman shift using a physical model that includes thermal expansion and three- and four-phonon anharmonic effects, which exhibits that the main origin of nonlinearity in both the phonon modes primarily arises from the three-phonon anharmonic process. We have also measured the interfacial thermal conductance (g) and thermal conductivity (ks) of the synthesized film using the optothermal Raman spectroscopy technique. The obtained values of g and ks are ∼7.218 ± 0.023 MW m−2 K−1 and ∼40 ± 2 W m−1 K−1, respectively, suggesting the suitability of thermal dissipation in MoS2 based electronic and optoelectronic devices. Furthermore, we performed a polarization study using the angle resolved polarized Raman spectroscopy technique under non-resonance and resonance excitations to reveal the electron–photon–phonon interaction in the prepared MoS2, based on the semi-classical theory that includes deformation potential and Fröhlich interaction. Our study provides much needed experimental information about thermal conductivity and polarization response in a few-layer MoS2 grown over the conducting substrate, which is relevant for applications in low power thermoelectric and optoelectronic devices.

An Easy-to-Use 3D-Printed Electrochemical Cell for I n Situ Raman Spectroscopy

In energy conversion devices such as electrolyzers and batteries, the monitoring of electrode surfaces during electrochemical processes is essential to understand their operation mechanisms. One of the promising techniques is in situ Raman spectroscopy, which can analyze (i) electrode surface structure, (ii) surface species (reaction intermediate species), and (iii) localized electrolyte species.1 The bottleneck for using this technique is the high cost and complexity of commercially available electrochemical cells designed for in situ Raman spectroscopy. To solve these issues, a few research groups provided 3D-printed spectroelectrochemical cells with low cost and less complexity.2,3 However, the spectroelectrochemical cells so far reported require a specific sample type (i.e., particles). We need a low-cost and less-complex spectroelectrochemical cell that can be used for more varieties of samples.In this study, we will provide a new design of a spectroelectrochemical cell that has compatibility with various sample types [i.e., substrates (e.g., metal foil strips, fluorine-doped tin oxide-coated glass, indium tin oxide-coated glass, etc.) and particle]. Specifically, a versatile, low-cost, and less-complex electrochemical cell for in situ Raman spectroscopy will be fabricated using a stereolithography (SLA) 3D printer with resin as a printing material. Herein, using the SLA 3D-printed spectroelectrochemical cell, we will also demonstrate a few example studies for electrolyzer and battery applications. References W. Zheng, Chemistry–Methods, 3, e202200042 (2023).M. F. dos Santos et al., Anal. Chem., 91, 10386–10389 (2019).G. D. da Silveira et al., Anal. Chim. Acta, 1141, 57–62 (2021).

Effect of deposition temperature on topography and electrochemical water oxidation of NiO thin films

The deposition temperature plays a significant role in controlling the crystallinity, morphology, and texture of thin films. Herein, we report the fabrication of nickel oxide thin films on a fluorine-doped tin oxide-coated glass substrate via a single-step aerosol-assisted chemical vapor deposition technique. Variable temperatures from 450 to 525 °C were used for the fabrication of these NiO thin films. The crystalline structure of nickel oxide thin films was determined by X-ray diffraction which showed cubic structure having space group Fm3m, and unit cell lattice parameters of a = b = c = 4.17 Å that crystallize preferentially along (200) plane. While the Raman spectroscopic study revealed the presence of peaks corresponding to nickel oxide structure. The surface chemical composition and oxidation states were investigated by X-ray photoelectron spectroscopy. Moreover, field-emission scanning electron microscopy aided in examining the temperature-dependent topography and microstructure of films. It was observed that when deposition temperature is increased from 450 to 525 °C, the bandgap energy decreased from 3.59 to 3.41 eV. The electrocatalytic activity for the oxygen evolution reaction was performed under alkaline conditions, using linear sweep voltammetry and cyclic voltammetry at different scan rates. Moreover, ohmic drop and charge transfer resistance are estimated by electrochemical impedance spectroscopy. The nickel oxide deposited at 500 °C showed the highest current density and the earliest onset overpotential as compared with other samples at different temperatures. Morphology-dependent catalytic activity is attributed to substrate temperature which significantly affects the growth of nickel oxide. Cyclic voltammetry reveals the Ni redox feature due to the active phase of nickel (oxy)hydroxide (NiOOH) and there was no significant current until 1.5 VRHE. Measurements of activity as a function of substrate temperature were consistent with the hypothesis that different morphology of the electrode exerts different charge transfer activation on nickel oxide. These results suggested that electrocatalysts coupled with controlled morphology can be tuned in terms of high performance, commercial applicability, and water-splitting devices.

Influence of ultrafast microwave deposition on morphology and growth mechanism of WO3 nanosheet photoanode for efficient bacterial inactivation and decomposition of organic pollutants

We report the ultrafast synthesis of WO3 nanosheet array photoanode on fluorine-doped tin oxide-coated glass without a seed layer by microwave-assisted deposition route. The ultrafast microwave-assisted synthesis at various microwave deposition cycles resulted in tailored WO3 morphologies with a monoclinic structure. The photoanode growth mechanism and effect of morphology tuning on the photoelectrochemical activities of WO3 photoanodes were studied in detail. Under one sun irradiation, the microwave-assisted WO3 photoanode prepared at four cycles (WO3-4 MW) exhibited a photocurrent density of 1.1 mA/cm2 at 1.0 V versus Ag/AgCl, whereas the WO3 photoanode prepared at two cycles (WO3-2 MW) achieved 0.68 mA/cm2. Further, hydrogen treatment of optimum WO3-4 MW photoanodes at 300 °C, 20 min and exhibited a high photoelectrochemical (PEC) degradation efficiency of Orange II dye (∼99 %/180 min) and BPA (98.5 % in 30 min). Additionally, ∼97 % E. Coli bacterial PEC inactivation was achieved within 120 min over H2-WO3-4 MW under one sun illumination irradiation. Also, plausible charge recombination/separation processes in microwave-assisted WO3/FTO and H2-WO3-4 MW photoanodes were also reported.

Preparation and characterization of sodium dodecyl sulfate/Ag nanoparticles constituting branched microfibers

Branched microfibers of sodium dodecyl sulfate/Ag nanoparticles were synthesized using a nanosecond laser at a wavelength of 532 nm. The synthesis process was investigated at three laser intensities (0.38, 0.76, and 1.53 MW/cm2) and five exposure times (5, 15, 30, 45, and 60 min). At intensities of 0.38 and 0.76 MW/cm2, with increasing the exposure time, the number of nanoparticles increases until an exposure time of 30 min. Above this, exposure saturation of the number of Ag nanoparticles takes place. A similar effect was detected for the size of nanoparticles at these laser intensities. The saturation effect begins at 5 min of exposure for a laser intensity of 1.53 MW/cm2. The estimated nanoparticle size ranges from 116 to 120 nm based on the exposure time for a laser intensity of 0.38 and 0.76 MW/cm2, respectively. Scanning electron microscopy images at low magnification show the branched microfiber structure, while at higher magnifications, nanoparticles of Ag covering these microfibers appear. Electron dispersion x-ray spectroscopy confirmed the presence of Ag. X-ray diffraction results for the particles deposited on a fluorine-doped tin oxide-coated glass substrate were discussed.

Agaricus bisporus Wild Mushroom Extract as Lectin Source for Engineering a Lactose Photoelectrochemical Biosensor

Agaricus bisporus mushroom biomass contains a lectin, ABL, with remarkable specificity for lactose biorecognition; in this work, this feature was explored to develop a photoelectrochemical biosensor. The high lectin activity found in saline extracts of this macrofungus (640 HU mL-1), even at critical pH values (4-10) and temperatures (20-100 °C), allowed its direct use as an ABL source. Theoretical and experimental evidence revealed favorable electrostatic and biocompatible conditions to immobilize ABL on a poly(methylene blue)/fluorine-doped tin oxide-coated glass platform, giving rise to the ABL/PMB/FTO biosensor. The conducting polymer added further photoactivity to the device, allowing the identification of lectin-carbohydrate interactions with even greater sensitivity. The dose-response curves studied by electrochemical impedance spectroscopy showed a sigmoidal profile that was well-fitted by Hill's equation, expanding the working dynamic range (15-540 nmol L-1 lactose; 20.2 pmol L-1 detection limit) and avoiding undesirable sample dilution or preconcentration procedures. Under the optimized photoelectrochemical conditions, the ABL/PMB/FTO biosensor showed remarkable signal stability, accuracy, specificity, and selectivity to analyze lactose in commercial food products. This research raises interest in ABL-based biosensors and the added value of the crude Agaricus bisporus extract toward the development of greener and more sustainable biotechnological approaches.

Electrochromic Displays via the Room-Temperature Electrochemical Oxidation of Nickel.

Electrochromism refers to the persistent and reversible change in color by applying an electric field. The phenomenon involves the insertion and extraction of electrons and ions within the active material. There is a keen interest in electrochromic (EC) materials, since they exhibit a wide range of potential applications. In recent years, transition-metal oxides have been widely investigated as EC materials due to their low power requirement, high coloration efficiency, and memory effect under an open-circuit condition. Nickel oxide (NiO), a p-type wide band gap semiconductor, exhibits attractive features such as a high color contrast ratio, good chemical stability, cost-effectiveness, and good compatibility with the cathodically coloring tungsten oxide. NiO thin films have been fabricated by various methods, but these are not cost-effective, scalable, or suitable for flexible applications. With the increasing demand for flexible and soft EC devices, it is essential to find routes to fabricate NiO thin films at lower temperatures. In this work, a NiO/Ni(OH)2-based thin EC layer on fluorine-doped tin oxide-coated glass is developed via an electroless nickel (EN) deposition route, followed by room-temperature electrochemical oxidation. The deposition time is optimized to control the film thickness. The EC performance is investigated in an aqueous alkaline electrolyte (1 M KOH) by means of cyclic voltammetry, chronoamperometry, and transmittance measurements. Both the as-deposited and annealed films, after electrochemical oxidation, exhibit excellent EC properties with an optical modulation of approximately 64% (at 550 nm) and good response times of approximately 3 s (coloration) and 14 s (bleaching). A 2 × 2 display obtained by patterning the EN deposition is also demonstrated as part of this work.

Application of Prussian Blue in Electrochemical and Optical Sensing of Free Chlorine.

In this paper, an electrochemical free chlorine (FCL) sensor was formed by modifying a fluorine-doped tin oxide-coated glass slide (glass|FTO) with a layer of Prussian blue (glass|FTO|PB). The glass|FTO|PB sensor exhibited a wide linear detection range from 1.7 to 99.2 μmol L−1 of FCL with a sensitivity of ~0.8 µA cm−2 μmol−1 L and showed high selectivity for FCL. However, , and ions have induced only a negligible amperometric response that is highly beneficial for a real-life sample analysis as these ions are commonly found in chlorine-treated water. Moreover, in this work, optical absorption measurement-based investigations of partially reduced PB were carried out as a means to characterize PB catalytic activity towards FCL and to investigate the possibility of applying PB for the optical detection of FCL.

Simply amplificated signal in electrochemiluminescence sensor using nano-gold film as a bridge

Normally, analytical applications of metal oxide semiconductors (MOS) in electrochemiluminescence (ECL) sensors need to be coupled with electrochemical catalysts, some special coreactants or resonance energy transfer method, since MOS exhibited relatively low ECL intensity. In this research, we developed a simple ECL intensity enhancement method for MOS by covering a nanogold-film (NAuF) on the surface of fluorine-doped tin oxide-coated (FTO) conductive glass electrode. Aminated MnO2 nanoparticles (NH-MnO2) was chosen as exemplary MOS emitter to discuss the role of NAuF in ECL system. The results indicated that the NAuF bridged ECL sensor using NH-MnO2 as emitter (NH-MnO2-NAuF/FTO) exhibited a stronger ECL intensity and extremely better stability. In furazolidone (FZD) determination test, the quenched ECL intensity showed a good linear relationship to FZD concentrations in the range 1.0 × 10−8 M ∼ 1.0 × 10−5 M, with a detection limit of 6.6 × 10−9 M, in optimized conditions. Given these attributes, we developed a novel platform for ECL system that could simply enhance the intensity and stability. This work also efficiently offered insights into application potential of ECL analysis.

Surface modification of p/n heterojunction based TiO2-Cu2O photoanode with a cobalt-phosphate (CoPi) co-catalyst for effective oxygen evolution reaction

The cobalt-phosphate decorated TiO2-Cu2O efficient heterojunction photoanode was successfully prepared using hydrothermal and electrodeposition methods. First, TiO2 was deposited onto fluorine-doped tin oxide-coated glass slides by the hydrothermal method, after which a layer of Cu2O was deposited by electrodeposition. Lastly, the surface of the TiO2-Cu2O electrode was further modified with cobalt-phosphate using photo-assisted electrodeposition. Prepared samples were characterized by X-ray diffractometry, field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy, and UV–Visible spectrophotometry. Substantial increase in photocurrent density, i.e., from 1.13 mA/cm2 to 1.66 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE) was observed when the optimized Cu2O layer was applied to the bare TiO2 photoanode. Moreover, the highest photocurrent density, i.e., 1.94 mA/cm2 at 1.23 V vs RHE was obtained when the surface of the TiO2-Cu2O heterojunction photoanode was further modified using a cobalt-phosphate co-catalyst. The remarkable performance of the p-n heterojunction structure photoanode was mainly attributed to improved light harvesting in the visible region and improved charge dynamics due to the band alignment between TiO2 and Cu2O.

Morphological exploration of chemical vapor–deposited P-doped ZnO nanorods for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is beneficial and has received attractive attention due to a greater potential to generate hydrogen and oxygen from water by using plentiful solar light to solve the problem of energy crisis. Various active semiconductor materials are used in PEC water splitting applications. Nevertheless, in past decades, most of the researchers suggested that titanium oxide (TiO2) is the best photoanode for this type of applications. Now, Zinc oxide (ZnO) is considered a perfect substitution to TiO2 due to its comparable energy band structure and superior photogenerated electron transfer rate. In this study, bare and phosphorous-doped ZnO nanorods were successfully developed on fluorine-doped tin oxide-coated glass (FTO) substrate by chemical vapor deposition. X-ray diffraction (XRD) pattern authenticated hexagonal structure formation with strong diffraction peak of (101), which showed that ZnO nanorods were perfectly developed along c axis. The optical and morphological properties were analyzed by UV–Vis and scanning electron microscopy images. The energy-dispersive X-ray spectra demonstrated that doping agent phosphorous was present in ZnO nanorods. The PEC properties of the developed ZnO nanorods were further investigated and obtained results suggested that a small amount of phosphorous-doped ZnO nanorods enhances their PEC performance.

Study of antimony selenide hole-transport material for Mo/Sb2Se3/MAPbI3/C60/GZO/Ag heterojunction planar solar cells

Antimony selenide (Sb2Se3) photovoltaic exhibits low energy band gap for effective wide solar spectrum utilization. A new heterojunction planar solar cell design has been investigated using thin Sb2Se3 hole-transporting material (HTM) layer between bi-layer molybdenum (Mo) electrode and CH3NH3PbI3 (MAPbI3) perovskite active absorbing layer. The solar cell structure was prepared as Mo/Sb2Se3/MAPbI3/C60/GZO/Ag on fluorine-doped tin oxide-coated glass substrate. Thus, the HTM layer, active absorbing layer, electron-transporting layer, transparent conductive oxide layer, and top electrode contact layer, has been made of Sb2Se3, MAPbI3, C60, gallium-doped zinc oxide, and silver, respectively. The Sb2Se3 HTM layers were also annealed at different temperatures of 300–600 °C. Scanning electron microscopy study showed improved crystal grains with the annealing temperature. This new heterojunction planar solar cell exhibited high power-conversion efficiency of 16.8% with the 200 nm Sb2Se3 HTM layer that was annealed at 600 °C. The device corresponding VOC, JSC, FF, Rs, and Pmax had been 1.07 V, 20.7 mA/cm2, 75.8%, 18.6 Ω, and 1.68 mW, respectively.

The type-II n-n inorganic/organic nano-heterojunction of Ti[formula omitted] self-doped TiO[formula omitted] nanorods and conjugated co-polymers for photoelectrochemical water splitting and photocatalytic dye degradation

In this article, we have reported the synthesis of two organic semiconductors which are anthraquinone and benzothia/selenadiazole-based π-conjugated D–A1–D–A2 (D-donor, A-acceptor) type co-polymers. We have coupled these organic semiconductors with the Ti3+ self-doped TiO2 nanorods (Ti3+/TiO2 NRs)—grown on the fluorine-doped tin oxide-coated glass substrate—to get type-II n-n inorganic/organic nano-heterostructures (NHs). Ti3+ self-doping effectively produces oxygen vacancies which, in turn, incorporates many sub-bandgap states in TiO2—making them visible-light active. The NHs electrodes acting as the photo-anodes initiate water oxidation under the visible-light illumination. The NHs not only boost the visible-light absorbance but also owing to the advantageous type-II band alignments, expedite better delocalization and faster transportation of the photogenerated carriers. The NHs comprising of benzothiadiazole (TP1) have been found exhibiting better photoelectrochemical performances than the Ti3+/TiO2 NRs as well as the NHs comprising of benzoselenadiazole (TP2). The saturated photocurrent densities offered by the TP1 and TP2 NHs electrodes at 1 V vs Ag/AgCl are 0.50 mA/cm2 and 0.30 mA/cm2, respectively, signifying almost 466.7% and 233.3% increments over the photo-current density shown by the Ti3+/TiO2 NRs electrode at 1 V vs Ag/AgCl. As far as the overall photocatalytic activities are concerned, the TP1 NHs thin film has shown the best performance. The photocatalytic efficiency for both of the NHs thin films substantially augmented in the presence of 1 mM H2SO4. This phenomenon is attributable to the photochemical formation of H2O2 because of the structural uniqueness of the polymers. Besides, experiments with the electron and hole scavengers admit the photocatalytic reactions are mostly dominated by electron mediated routes for both of the NHs. The photogenerated electrons produce •OH radicals which govern the holistic degradation mechanism.

Fabrication and photoelectrochemical activity of hierarchically Porous TiO2–ZnO heterojunction film

For the first time, we report the fabrication of hierarchically (macro with nested meso) porous nanocrystalline TiO2–ZnO heterojunction film onto fluorine-doped tin oxide-coated glass substrate by colloidal crystal templating technique using poly(methyl methacrylate) (PMMA) spheres as template. Accordingly, the precursor solutions of titanium isopropoxide and zinc acetate dihydrate in the presence of Pluronic P123 were used to impregnate the individual solution into the template. Initially, nanocrystalline TiO2 inverse opal mesoporous film was deposited using the titanium precursor. The film was cured at 450 °C in an air atmosphere. A similar process was adopted to deposit nanocrystalline ZnO inverse opal mesoporous film onto the TiO2 to obtain hierarchically porous TiO2–ZnO heterojunction nanocrystalline film. Morphology of the fabricated films showed a periodic arrangement of macropores, whereas the microstructural analysis confirmed the presence of nested mesopores in the film network. Chemical interaction existed between TiO2 with ZnO forming the heterojunction film was ascertained by X-ray photoelectron spectroscopy. Light harvesting efficiency of the samples was studied, and the photoelectrochemical (PEC) performance of the hierarchically porous heterojunction films as photoanode showed about 5 times enhancement in photocurrent density compared to the pristine metal–oxide–semiconductor film under visible light exposure. The porous nanocrystalline hierarchically porous inverse opal heterojunction film could be used as an efficient photoanode in PEC cell.

A Bilayer Structure Composed of Mg|Co-MnO2 Deposited on a Co(OH)2 Film to Realize Selective Oxygen Evolution from Chloride-Containing Water.

A fluorine-doped tin oxide-coated glass electrode modified with a bilayer film of underlying α-Co(OH)2 and overlying Mg-intercalated and Co-doped δ-type (layered) MnO2 (Mg|Co-MnO2) preferentially yielded oxygen with a Faradaic efficiency as high as 79% in the presence of chloride ions at high concentration (0.5 M). This noble metal-free electrode was fabricated by cathodic electrolysis of aqueous Co(NO3)2 followed by anodic electrolysis of a mixture of Mn2+, Co2+, and cetyltrimethylammonium (CTA+) ions in water. The CTA+ ions accommodated in the interlayer spaces of Co-doped δ-MnO2 were replaced with Mg2+ by ion exchange. The upper Mg|Co-MnO2 could effectively block the permeation of Cl- ions and allow only H2O and O2, while the under α-Co(OH)2 acted as an oxidation catalyst for the H2O penetrated through the upper coating. Thus, the oxygen evolution reaction (OER) was preferred to the chlorine evolution reaction (CER). In artificial seawater (pH 8.3), the blocking effect against Cl- decreased because of ion exchange of the intercalated Mg2+ ions with Na+ in solution, but the OER efficiency still remained at 57%, much higher than that (28%) without the upper Mg|Co-MnO2. This demonstrates that the interlayer spaces between MnO2 layers acted as pathways for H2O molecules to reach the active sites of the underlying Co(OH)2. Density functional theory (DFT) calculations revealed that the most stable structure of hydrated Mg2+ ion, in which a part of coordinated H2O molecules is hydrolyzed, has less affinity toward Cl- ion than that of hydrated Na+ ion.

Electrodeposited chromium-doped α-Fe2O3 under various applied potential configurations for solar water splitting

In this work, high quality hematite (α-Fe2O3) Chromium (Cr)-doped thin films have been synthesized via electrodeposition technique, on fluorine-doped tin oxide-coated glass substrates, under various applied potential configurations [cyclic voltammetry (CV), linear sweep voltammetry (LSV) and −0.5 V]. Chromium was added to the electrolyte at such a proportion that the Cr/(Cr + Fe) ratio remained within 8%. The as-deposited films were subsequently annealed in air at 650 °C for 2 h. Our novel study highlights the effect of using variable potential approaches during the film preparation on the properties of Cr-αFe2O3 deposited films. The prepared thin films were analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV–Vis absorption and photoelectrochemical (PEC) analysis. XRD revealed that samples are crystallized in Cr-Fe2O3 cubic structure with a crystalline orientation in the plane (1 1 1) and a clear improvement of the crystallinity and size crystallite of the Cr-Fe2O3 deposited using CV process. SEM micrographs showed that the morphology grains were three-sided pyramid-shaped, expanding with increase of the crystallinity. The calculated band gap values are 2.18, 2.23 and 2.20 eV, respectively for −0.5 V, LSV, CV. The Cr-Fe2O3 films synthesized in this study showed high PEC activity with very low carrier density in comparison with the conventionally electrodeposited films. This Cr-doped hematite films ‘excellent photoelectrochemical performance was mainly attributed to improved charge carrier properties. Such high photoactivity was attributed to the large active surface area and increased donor density caused by increasing the Cr doping in the α-Fe2O3 films.

Growth of ZnO nanorods on FTO glass substrate

A simple and direct method has been developed to grow zinc oxide (ZnO) nanorods (NRs) on a fluorine-doped tin oxide-coated glass (FTO) substrate. Firstly, spray pyrolysis deposition method is applied followed by dipping the substrate in a solution of ZnO growth reagents. The morphology, structure, and optical properties of the obtained thin film are investigated. The results demonstrate the successful synthesis of the ZnO NRs on FTO substrate. The NRs have a hexagonal rod like structure with diameter and length of 240 nm and 670 nm, respectively. FTO/ZnO NRs exhibited absorption of UV wavelengths and high transmittance in visible light region, with energy bandgap (Eg) of 3.2 eV. The characteristics of the FTO/ZnO NRs film can be explored in photovoltaic applications such as dye-sensitized solar cells.

Electrodeposited Cr-Doped α-Fe2O3 thin films active for photoelectrochemical water splitting

Polycrystalline hematite (α-Fe2O3) Chromium (Cr)-doped thin films were electrodeposited on fluorine-doped tin oxide-coated glass substrates. The electrodeposition bath comprised an aqueous solution containing FeCl3·6H2O, NaCl, and H2O2.Chromium was added to the electrolyte at such a proportion that the Cr/(Cr + Fe) ratio remained within the 2–8 at. % range. The as-deposited films were subsequently annealed in air at 650 °C for 2 h. The structure and morphological characteristics of the undoped and Cr-doped α-Fe2O3 thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Vis spectroscopy. Cr doping led the main XRD lines to shift to lower angles, which mostly resulted from substituting Fe3+ for Cr4+ ions that leads to α-Fe2O3 lattice contraction. The SEM observations showed that the roughness and aspect of surfaces changed with the Cr doping level. The photoelectrochemical (PEC) performance of the α-Fe2O3 films was examined by chronoamperometry and linear sweep voltammetry techniques. The Cr-doped films exhibited greater photoelectrochemical activity than the undoped α-Fe2O3 thin films. The highest photocurrent density was obtained for the 8% Cr-doped α-Fe2O3 films in 1 M NaOH electrolyte. All the samples achieved their best IPCE at 400 nm. The IPCE values for the 8 at.% Cr-doped hematite films were 20-fold higher than that of the undoped sample.This Cr-doped hematite films ‘excellent photoelectrochemical performance was mainly attributed to improved charge carrier properties. Such high photoactivity was attributed to the large active surface area and increased donor density caused by increasing the Cr doping in the α-Fe2O3 films.

Growth and morphology control of CH3NH3PbBr3 crystals

We present here an experimental study on the growth of CH3NH3PbBr3 crystals by conventional spin coating and simple drop casting methods. We observed directly that under the diffusion-limited regime, large-size cuboids and pyramid-like single crystals were obtained. Single-crystal X-ray diffraction revealed that these crystals were in the Pm-3m cubic crystalline structure phase, with a refined unit size of 5.93 A. Polycrystals with fractal-like or snowflake-like morphologies were grown by spin coating method, on fluorine-doped tin oxide-coated glass substrates, that we referred to as the attachment kinetics-limited regime. Interestingly enough, with the same technique, cuboids CH3NH3PbBr3 single crystals were obtained on bare glass substrates. These single crystals and polycrystals exhibited a very strong photoluminescence effect. This study paves a way for controlled growth of CH3NH3PbBr3 crystals and their advanced optoelectronic applications.