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Electrochromic performance of chromium-doped Co3O4 nanocrystalline thin films prepared by nebulizer spray technique
摘要： Pristine and chromium (Cr)-doped tricobalt tetraoxide (Co3O4) thin films were grown on glass and FTO substrates by nebulized spray pyrolysis technique. The structural, optical and electrical properties of the pristine and Cr-doped Co3O4 films were characterized by X-ray diffraction, scanning electron microscopy, Raman, and four-probe method. The chemical environment of the elements present in the films was identified from energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The effect of chromium doping on optical constants is discussed in detail. The electrochromic studies reveal that better optical modulation (?T = 38.3%) and high coloration efficiency (CE = 47 cm2/C) were obtained for 6 at. % of Cr-doped Co3O4 film. The present work suggests that incorporation of Cr in Co3O4 will enhance its electrochromic performance.
关键词： Nebulized spray pyrolysis,Electrochromism,Cr-doped Cobalt oxide,Optical properties
更新于2025-09-23 15:23:52
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Atomic layer deposition of cobalt(II) oxide thin films from Co(BTSA) <sub/>2</sub> (THF) and H <sub/>2</sub> O
摘要： In this work, we have studied the applicability of Co(BTSA)2(THF) [BTSA = bis(trimethylsilyl)amido] (THF = tetrahydrofuran) in atomic layer deposition (ALD) of cobalt oxide thin films. When adducted with THF, the resulting Co(BTSA)2(THF) showed good volatility and could be evaporated at 55 °C, which enabled film deposition in the temperature range of 75–250 °C. Water was used as the coreactant, which led to the formation of Co(II) oxide films. The saturative growth mode characteristic to ALD was confirmed with respect to both precursors at deposition temperatures of 100 and 200 °C. According to grazing incidence x-ray diffraction measurements, the films contain both cubic rock salt and hexagonal wurtzite phases of CoO. X-ray photoelectron spectroscopy measurements confirmed that the primary oxidation state of cobalt in the films is +2. The film composition was analyzed using time-of-flight elastic recoil detection analysis, which revealed the main impurities in the films to be H and Si. The Si impurities originate from the BTSA ligand and increased with increasing deposition temperature, which indicates that Co(BTSA)2(THF) is best suited for low-temperature deposition. To gain insight into the surface chemistry of the deposition process, an in situ reaction mechanism study was conducted using quadrupole mass spectroscopy and quartz crystal microbalance techniques. Based on the in situ experiments, it can be concluded that film growth occurs via a ligand exchange mechanism.
关键词： atomic layer deposition,reaction mechanism,thin films,Co(BTSA)2(THF),cobalt oxide,water
更新于2025-09-23 15:23:52
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Solution-processed p-type nanocrystalline CoO films for inverted mixed perovskite solar cells
摘要： Inorganic p-type materials show great potential as the hole transport layer in perovskite solar cells with the merits of low costs and enhanced chemical stability. As a p-type material, cobalt oxide (CoO) has received so far not that level of attention despite its high hole mobility. Herein, solution-processed p-type CoO nanocrystalline films are developed for inverted mixed perovskite solar cells. The ultrafine CoO nanocrystals are synthesized via an oil phase method, which are subsequently treated by a ligand exchange process using pyridine solvent to remove the long alkyl chains covering the nanocrystals. From this homogeneous colloidal solution CoO films are obtained, which exhibit a smooth and pin-hole free surface morphology with high transparency and good conductivity. The ultraviolet photoelectron spectrum also indicates that the energy levels of the CoO film match well with the mixed perovskite Cs0.05(FA0.83MA0.17)0.95(I0.83Br0.17)3. Inverted solar cells based on crystalline CoO films with ligand exchange show a reasonable energy conversion efficiency, whereas devices based on CoO films without ligand exchange suffer from a strong S-shape JV-characteristic. Thus, the crystalline CoO films are foreseen to pave a new way of inorganic hole transport materials in the fields of perovskite solar cells.
关键词： Perovskite solar cells,p-type,Cobalt oxide,Colloids,Hole transport layers
更新于2025-09-23 15:21:01
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Laser fragmentation induced defect‐rich cobalt oxide nanoparticles for electrochemical oxygen evolution reaction
摘要： Sub-5 nm cobalt oxide nanoparticles were produced in a water flowing system by pulsed laser fragmentation in liquid (PLFL). Particle fragmentation from 8 nm to 4 nm was observed and proposed to be induced by the oxidation process in water where oxidative species were present and the local temperature was rapidly elevated under laser irradiation. Significantly higher surface area, crystal phase transformation and formation of structural defects (Co2+ defects and oxygen vacancies) through the PLFL process were evidenced by a detailed structural characterization using nitrogen physisorption, electron microscopy, synchrotron X-ray diffraction and X-ray photoelectron spectroscopy. When employed as electrocatalysts for the oxygen evolution reaction under alkaline conditions, the fragmented cobalt oxides exhibited superior catalytic activity over pristine and nanocasted cobalt oxides, with delivering a current density of 10 mA/cm2 at 369 mV and a Tafel slope of 46 mV/dec, which is attributed to: (i) a larger exposed active surface area, (ii) formation of defects and iii) an increased charge transfer rate. The study provides an effective approach to engineer cobalt oxide nanostructure in a water flowing system, which shows great potential for sustainable production of active cobalt catalysts.
关键词： structural defects,cobalt oxide,nanostructure,Oxygen evolution reaction,laser fragmentation
更新于2025-09-11 14:15:04
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Synthesis and improved photoluminescence of hexagonal crystals of Li <sub/>2</sub> ZrF <sub/>6</sub> :Mn <sup>4+</sup> for warm WLED application
摘要： Engineering compositions, structures, and defects can endow nanomaterials with optimized catalytic properties. Here, we report that cobalt oxide (CoOx) ultrathin nanosheets (UTNS, ～1.6 nm thick) with a large number of oxygen defects and mixed cobalt valences can be obtained through a facile one-step hydrothermal protocol. The large number of oxygen defects make the ultrathin CoOx nanosheet a superior OER catalyst with low overpotentials of 315 and 365 mV at current densities of 50 and 200 mA cm?2, respectively. The stable framework-like architectures of the UTNS further ensure their high OER activity and durability. Our method represents a facile one-step preparation of CoOx nanostructures with tunable compositions, morphologies, and defects, and thus promotes OER properties. This strategy may find its wider applicability in designing active, robust, and easy-to-obtain catalysts for OER and other electrocatalytic systems.
关键词： ultrathin nanosheets,oxygen evolution reaction,electrocatalysis,hydrothermal synthesis,cobalt oxide
更新于2025-09-11 14:15:04
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From nano-structured polycrystalline spheres with Zn1-xCoxO composition to core-shell Zn1-xCoxO@SiO2 as green pigments
摘要： ZnO doped with Co2+, a well-known green pigment which is an alternative to the chromium based inorganic pigments, has been prepared by a polyol process and investigated in terms of crystallographic structure and UV?visible properties. Thanks to the obtaining of nanometric crystallite size from our process, the incorporation of a very high concentration of Co2+ in the ZnO matrix is achieved. Thus, different grades of more or less deep green pigments can be produced. Furthermore, the obtaining of spherical aggregates allows the easy preparation of ZnO:Co@SiO2 core-shells, minimizing hence the problems linked to the zinc oxide high solubility into slightly acidic conditions acidic conditions and the metal cation’s toxicity.
关键词： Core-shell,Zinc-Cobalt oxide,Green Pigment,Polyol synthesis
更新于2025-09-10 09:29:36
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Substrate temperature-dependent properties of sprayed cobalt oxide thin films
摘要： Cobalt oxide (Co3O4) thin films were deposited onto amorphous glass substrates using a home-made pneumatic spray pyrolysis system (SPT) from aqueous solution of cobalt chloride salt (CoCl2) as a source of cobalt. The films were deposited at different substrate temperatures ranging from 250 to 450?°C in steps of 50?°C. The effect of substrate temperature on structural, electrical and optical properties was studied. The characterization of samples was carried out by X-ray diffraction (XRD), UV–Vis spectroscopy, energy dispersive spectroscopy (EDS), scanning electron microscopy and four probe points measurements. The XRD study showed that all the films were polycrystalline consisting of Co3O4 spinel cubic phase. The preferred orientation of the crystallites changed from (311) to (111) when the substrate temperature increases. The average calculated grain size was about 40.38?nm. Morphological studies exposed that the films surface morphology is almost homogeneous and well-covered. Peaks associated with Co and O elements are present in EDS analysis witch confirm the composition of the films. The optical transmittance and the band gaps energy increase with the increase of substrate temperature. The measured electrical conductivity at room temperature was found in the order of 10?1 (??cm)?1.
关键词： Thin films,Substrate temperature,Cobalt oxide,Spray pyrolysis,Structural properties,Optical properties,Electrical properties
更新于2025-09-10 09:29:36
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Role of the reactive sputtering deposition power in the phase control of cobalt oxide films
摘要： The influence of the reactive magnetron sputtering deposition power on determining the stoichiometry and structure of cobalt oxide polycrystalline films is investigated using experimental and simulated data. Direct current discharges with powers in the 80–240 W range are tested using a metallic Co target and an Ar + O2 plasma. X-ray diffraction results show that lower deposition powers favor the spinel Co3O4 phase, while higher powers produce films presenting the rocksalt CoO phase. Computer simulations indicate that lower power processes occur in the poisoned target regime, while higher power depositions favor the metallic target regime. Consistent with the simulations, oxygen optical emissions (OI = 777:3 m) from the plasma show a significant decrease while the cobalt emissions (e.g., the CoI = 340:5 nm line) are significantly increased when the deposition power is increased. The results show that the film stoichiometry and structure are directly related to the deposition power, at constant O2 flow.
关键词： optical emissions,deposition power,X-ray diffraction,reactive sputtering,cobalt oxide,phase control
更新于2025-09-10 09:29:36
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Cobalt oxide loaded graphitic carbon nitride as adsorptive photocatalyst for tetracycline removal from aqueous solution
摘要： The treatment of antibiotic-containing wastewater is of great importance due to the potential threats of antibiotics to human and the ecosystem. We reported the preparation of cobalt oxide loaded graphitic carbon nitride (CoO/g-C3N4) by an impregnation-calcination method for tetracycline (TC) removal from aqueous solution. The developed CoO/g-C3N4 exhibited high adsorption capacity and fast adsorption kinetic for TC due to the complexation of TC with surface loaded CoO. In particular, 7%CoO/g-C3N4-3 sample presented a maximum TC adsorption capacity of 391.4 mg g-1. It was found that Langmuir and pseudo-second order kinetic models fitted TC adsorption process well. Further photocatalytic studies showed that CoO loaded g-C3N4 was active for TC photodegradation, although the photocatalytic reaction rate constant was lower than that of native g-C3N4. CoO nanoparticles loading on g-C3N4 played the major role of adsorption sites rather than cocatalyst for photocatalysis. We believe that the developed CoO/g-C3N4 could be a potential adsorptive photocatalyst for antibiotic pollutants removal from wastewater.
关键词： Graphitic carbon nitride,antibiotic,photocatalysis,adsorption,cobalt oxide
更新于2025-09-10 09:29:36
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N-S Codoped Cerium-Cobalt Oxide Bimetal Nanoparticles Catalyzed Photodegradation of Brilliant Green and Fast Green
摘要： Cerium-cobalt oxide bimetal nanoparticles were synthesized using wet precipitation method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalyzed degradation of brilliant green and fast green dyes were studied using CeCoO3 bimetallic nanoparticles spectrophotometrically. Photocatalytic activity has been tested in the reaction of these dyes under visible irradiation. It was revealed that doping enhanced the photocatalytic activity at low doping levels but reduced the activity at high doping levels. Various parameters like amount of semiconductor, pH, light intensity, dye concentration, % of dopant were also studied. The rate of reaction followed pseudo-first order kinetics.
关键词： Nanoparticles,Fast green,Brilliant green,Cerium-Cobalt oxide,Photodegradation
更新于2025-09-09 09:28:46