Spray Pyrolysis Method Research Articles

A Comparative Study of NiCo2O4, NiO, and Co3O4 Electrocatalysts Synthesized by a Facile Spray Pyrolysis For Electrochemical Water Oxidation

AbstractExploiting low‐cost, highly active, and robust oxygen evolution reaction (OER) electrocatalysts based on earth‐abundant elements by a simple synthesis approach holds paramount importance for green hydrogen production through water electrolysis. In this work, the NiO, Co3O4 and NiCo2O4 nanoparticle layers with identical surface morphologies are prepared under same deposition conditions by a simple spray pyrolysis method and their OER activities are comparatively investigated. Among all these three electrocatalysts, NiCo2O4 shows the lowest overpotential of 420 mV to drive benchmark current density of 10 mA cm−2 and the smallest Tafel slope (84.1 mV dec−1), which are comparable to the OER performance of the benchmark commercial RuO2 electrocatalyst. The high OER activity of NiCo2O4 is attributed to the synergy effect and the modulation of electronic properties between Co and Ni atoms, which drastically reduces the overpotential required to drive OER activities. Therefore, it is believed that the NiCo2O4 synthesized by this simple method would be a competitive candidate as an industrial electrocatalyst with high‐efficiency and low cost for large‐scale green hydrogen production via water electrolysis.

Facile large–scale synthesis of 3D crumpled N, O co–doped graphene nanosheets and their electrochemical properties

Graphene, as a highly promising electrode material, has garnered significant attentions due to its remarkable properties. Nevertheless, challenges persist in its commercial application in the field of energy storage and conversion, including easy stacking, inert surface and limited yield. Rational regulation of the morphology, structure and composition of graphene is demonstrated as an effective way to conquer these challenges. Herein, we adopt a facile spray pyrolysis method to achieve large–scale synthesis of 3D crumpled N, O co–doped graphene nanosheets (NO–GNs). By comprehensive characterization and analysis, it is witnessed that our prepared NO–GNs possess unique 3D crumpled morphology as well as abundant structure defects, and achieve successful co–doping of N and O atoms. These optimized morphology, structure and composition effectively increase the specific surface area and substantially enhance the hydrophilicity and reactive activity of NO–GNs, thus leading to markedly improved electrochemical performance towards supercapacitor and oxygen reduction reaction. Evidently, the preparation of NO–GNs not only offers a promising material for advanced energy storage and conversion systems, but also presents a novel but versatile strategy for manufacturing high–performance carbon–based electrodes.

Stabilizing Cu+ Species in Cu2O/CuO Catalyst via Carbon Intermediate Confinement for Selective CO2RR

AbstractCopper oxide nanomaterials have been suggested to be efficient for highly selective multi‐carbon (C2+) production in CO2 reduction reaction (CO2RR), due to the introduction of surface Cu+ species from oxide catalysts. However, the Cu+ species on the catalyst surface are prone to being reduced to Cu0 under reductive conditions during CO2RR. Here, a network‐structured catalyst is developed consisting of ultrafine Cu2O/CuO nanoparticles that harbor an abundance of pores. This catalyst is synthesized via flame spray pyrolysis (FSP) method and engineered to confine carbon intermediates, which subsequently cover the local catalyst surface and stabilize Cu+ species. As a result, a C2+ products Faradaic efficiency (FE) of approximately 80.0% at a partial current density of 320.0 mA cm−2 is achieved, and a large C2+ to C1 ratio of ≈9.7. In situ XRD and XPS spectra are employed to reveal the indeed presence of Cu+ species on the catalyst surface during the CO2RR process, which extensively improves the adsorption of *CO intermediates and thus the C─C coupling reaction to form C2+ products.

Recovery of Magnetic Particles from Wastewater Formed through the Treatment of New Polycrystalline Diamond Blanks

Cobalt’s pivotal role in global development, especially in lithium-ion batteries, entails driving increased demand and strengthening global trading networks. The production of different waste solutions in metallurgical operations requires the development of an environmentally friendly research strategy. The ultrasonic spray pyrolysis and hydrogen reduction method were chosen to produce nanosized magnetic powders from waste solution based on iron and cobalt obtained during the purification process of used polycrystalline diamond blanks. With specific objectives focused on investigating the impact of reaction temperature and residence time on the morphology, chemical composition, and crystal structure of synthesized nanosized cobalt powders, our research involved 15 experimental runs using two reactors with varying residence times (7.19 s and 23 s) and distinct precursors (A, B, and C). Aerosol droplets were reduced at 600 to 900 °C with a flow rate of 3 L/min of argon and hydrogen (1:2). Characterization via scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction revealed that higher temperatures influenced the spherical particle morphology. Altering cobalt concentration in the solution impacted the particle size, with higher concentrations yielding larger particles. A short residence time (7.9 s) at 900 °C proved optimal for cobalt submicron synthesis, producing spherical particles ranging from 191.1 nm to 1222 nm. This research addresses the environmental significance of recovering magnetic particles from waste solutions, contributing to sustainable nanomaterial applications.

Characterizations of sprayed TiO2 and Cu doped TiO2 thin films prepared by spray pyrolysis method

TiO2 and TiO2:Cu films were deposited by spray pyrolysis (SP). X-ray diffraction reveals that deposited films have a polycrystalline structural. The AFM image of the surface reveals that roughness and root mean square affected by doping. Optical transmission of films was found to decrease from 94 % to 84 % with the as the doping percentage increase to 3. Optical bandgap (Eg) of TiO2 thin film was 3.947eV. The bandgap is shifted to lower energies upon doping.

Effect thickness of copper oxide thin films on structural, optical, electrical, and hydrophobic properties for use in self-cleaning technique

In this work, copper oxide thin films were deposited by pneumatic spray pyrolysis method on a microscopy glass substrate, heated at 400°C for different deposition times (5min, 10min, 15min, 20min,25min, and 30min) using a 0.1M of precursor concentration. These films are characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), spectroscopic ellipsometry, UV-visible spectroscopy, four points method, and water contact angle. According to the XRD, all peaks confirm the formation of the phase tenorite of the monoclinic structure. The deposited were polycrystalline copper oxide CuO with directions along (111) plane, the crystallites size between 14 and 23 nm. FTIR spectroscopy confirms the presence of the CuO phase and agrees that it will result in XRD. From the transmission spectra, the average transmission between 400 and 800nm is 65% to 50%, and the gap energy is 2.65 eV to 1.09 eV. The water contact angle values in all samples are greater than 90° and range from 96.4° to 103.2°, as we can see from these results that all the samples are hydrophobic films.

Effect of substrate temperature on the properties of spray-deposited Cu2NiSnS4 films

Recently, quaternary Cu2NiSnS4 (CNTS) material has emerged as one of the best promising materials for photovoltaic applications. The spray pyrolysis method was employed to deposit CNTS films by varying substrate temperatures from 250 to 450 °C. All the XRD patterns are polycrystalline with (111) preferred orientation having the crystallite size of 11 nm. The compact, interconnected grains with sizes ranging from 130 to 250 nm are observed from the SEM analysis. The Raman peaks observed at 291, 335, and 348 cm−1 correspond to the cubic CNTS phase. Also, the NiS1.97 and Cu8S5 secondary phases are occurred at 137 and 477 cm−1, respectively. All films show the presence of Cu:Ni:Sn:S with good elemental composition. Taut plot shows the band gap of 1.49 eV for cubic CNTS along with NiS1.97 (1.37 eV) and Cu8S5 (1.38 eV) phases. So, the CNTS material can be a good candidate for photovoltaic applications.

Preparation and characterization of graphene-based fluorine doped tin dioxide thin films via spray pyrolysis technique

Abstract In this work, fluorine-doped tin oxide (FTO) and graphene/fluorine-doped (G-FTO) thin films were prepared using a low-cost spray pyrolysis method at a substrate temperature of 500 °C. For the FTOs, stannous chloride was dissolved in methanol and acetic acid to form the precursor solution. A 0.05 mole (M) of hydrofluoric acid was added to the precursor as an n-type impurity. The FTO thin film has an optical transmittance of 82% and electrical sheet resistance of 15 Ω/□. By meticulously integrating graphene into the optimal precursor solution of FTO, a significant improvement in the electrical conductivity of the prepared samples was achieved, leading to a reduction in the sheet resistance to 8 Ω/□ with a suitable optical transmittance of 79%. Structural, morphological, optical, and electrical properties of the prepared sample are investigated using X-ray diffraction, scanning electron microscope, UV spectroscopy, and four-point probe technique. The best performance of the FTO thin films is achieved utilizing 2.5 µmole/L of fluorine concentration at a substrate temperature of 500°C for a spraying exposer time of 20 min. The prepared sample has an electrical sheet resistance of 15 Ω/□, optical transmittance of 82%, and figure-of-merit of 91.2×10−4 Ω−1.The addition of 0.4 µmole/L of graphene to the optimum FTO samples enhances the performance by a remarkable reduction in the electrical the sheet resistance to 8 Ω/□ and an acceptable reduction in the optical transmittance of 79%. The overall value of the figure-of-merit increased to 118.3×10−4 Ω−1. The achieved results offer a high potential for adopting the prepared films for electronic and optoelectronic applications.

Tin Oxide Nanoparticles: A Review

Abstract: The aim of this review article is an overview of the tin oxide (SnO2) nanoparticles, and the literature addresses the existing research related to the various modifications and characterization of SnO2 nanoparticles with their physicochemical investigations. Among various metal-oxide nanoparticles, SnO2 nanoparticles are considered one of the potential candidates for electronic and electrical device fabrication, sensors, display devices, gas sensing, photovoltaic devices, LIBs (Lithium-ion batteries), photocatalysis and optoelectronic devices, supercapacitors, SnO2 nanowires would provide electrolyte channels for effective transport, catalyst, and anode materials. Apart from their technological supremacy, SnO2 nanoparticles have demonstrated their compatibility with human cervical cancer cells and have successfully achieved hyperthermia temperature when subjected to an alternating current magnetic field. Doping with some of the potential rare-earth dopants via various synthesis methods such as Chemical co-precipitation, sol-gel, polymeric precursor method, and nebulizer spray pyrolysis method is the major highlight of this review article. As per the requirement of the system, SnO2 nanoparticles can be tuned by size, shape, and functionality.

Preparation and chemical stability evaluation of Ln2Zr2O7‐SrZrO3 novel composite ceramics cured simultaneously with An and 90Sr

AbstractIn response to the low separation efficiency of actinide nuclide (An) and fission product (FP) in the separation process of high‐level radioactive waste, as well as the large amount of secondary waste. A novel Ln(1‐x)SrxZrO(3.5‐0.5x) (0 ≤ x ≤1) multiphase ceramic waste form (Nd3+ simulating An3+), which can cure both An and Sr simultaneously, was in‐situ synthesized by sol‐gel spray pyrolysis method. The series of multiphase ceramics are composed of cubic pyrochlore phase Nd2Zr2O7 (NZO) and orthorhombic perovskite phase SrZrO3 (SZO), without any accompanying impurities. The two phases exhibit excellent compatibility, and their content can change regularly with the change of x. Nd and Sr occupy their most stable crystal lattice positions, with low transposition doping levels. The density of the composite ceramics is high, and the measured density is as high as 88 % of the theoretical density. The above experimental results confirm that the new multiphase ceramics can cure An and Sr simultaneously and separately, showing strong adaptability to waste components and high chemical stability.

Comparative study of Cu2XSnS4 (X = Ni, Co, Mn or Fe) films synthesized by spray pyrolysis under air atmosphere, as suitable absorber layers for photovoltaic applications

The present work deals with the synthesis of an absorber Cu2XSnS4 sulfide (X = Ni, Fe, Co or Mn) thin films by a spray pyrolysis method on hot substrate and under air atmosphere for low cost solar cell. Chemical composition analyzes by energy-dispersive X-ray spectroscopy (EDS) revealed the presence of all the chemical elements (Cu, Sn, S and Co, Ni, Mn or Fe) with a composition close to the stoichiometry of the layers of Cu2NiSnS4 (CNTS), Cu2CoSnS4 (CCTS) and far from the stoichiometry for the layers of Cu2MnSnS4 (CMTS) and Cu2FeSnS4 (CFTS). The X-ray diffraction (XRD) analyzes showed the crystallization of the desired phase such as the cubic phase of CNTS with a preferential orientation (111) and the stannite phase of CCTS and CMTS with a preferential orientation (112), except for the CFTS film which is poorly crystallized. SEM analyzes show that CNTS, CCTS and CMTS layers exhibit a rather homogeneous and compact surface with nodule distribution. The CFTS layer surface shows excrescences separated by voids leading to a porous and diffusing surface. The optical analyzes indicated a high absorption coefficient of the order of 104 cm−1 in the visible range for all the layers and an optical band gap of 1.62, 1.58 and 1.64 eV for the layers CNTS, CCTS and CMTS respectively, whereas the direct band gap of CFTS film is higher (∼ 2.23 eV). The comparison of CXTS films synthesized in the same conditions demonstrates that the CNTS and CCTS films have the most suitable features (optical, electrical, mechanical and oxidation resistance) to be used as absorbing layer in low cost solar cell.

Switching the selectivity of ZnO thin films for ultra-sensitive acetaldehyde gas sensors through Co doping

Pure and Co doped (1–5 wt%.) ZnO thin films were synthesised using the chemical spray pyrolysis method for the detection of acetaldehyde at 300 K. The gas sensing properties of these films were studied. The preferential orientation of the films along the c-axis stated its high crystalline nature. The responsiveness of the Co doped films switched to acetaldehyde from ammonia of the pure ZnO film. The 5 wt%. Co doped ZnO films could effectively detect 5 ppm of acetaldehyde at 300 K with a better response of around 238, compared to the pure and other doping concentrations. This high response is due to the catalytic property of Co, whose presence changed the electrical properties of the film. Co2+ created Zn2+ vacancies over the surface and generated defects, promoting the gas sensing mechanism. The constructed sensing layer is stable and repeatable implying its potential application as an acetaldehyde gas sensor.

Antibacterial and In Vitro Bioactivity Studies of Silver-Doped, Cerium-Doped, and Silver–Cerium Co-Doped 80S Mesoporous Bioactive Glass Particles via Spray Pyrolysis

Researchers are concentrating on discovering reducing treatments for bacterial infections due to the worrisome and quick rise of drug-resistant microbial-related illnesses. Metallic ion doping and co-doping mesoporous bioactive glass (MBG) can defend against drug-resistant pathogens of Escherichia coli (E. coli) infection of wounds and solve the issues of bone deformities. In this study, un-doped MBG, silver-doped MBG (Ag-doped MBG), cerium-doped MBG (Ce-doped MBG), and silver–cerium co-doped MBG (Ag-Ce co-doped MBG) have been successfully synthesized via the spray pyrolysis method. In addition, various characterization techniques, including X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption–desorption, were used to investigate the phase compositions, surface morphologies, chemical compositions, inner structure morphologies, chemical bonds/functional groups, and specific surface areas, respectively. The antibacterial efficacy against E. coli was assessed using the colony count technique. All types of MBG with Ag, Ce, and Ag-Ce were effective against E. coli. Furthermore, when immersed in simulated body fluid, the MBGs formed hydroxyapatite and could be used to improve bone defects. Only 5.75 mol% Ag-doped MBG showed toxicity in the MTT assay test. According to our analysis, the 80S-Ag-Ce-MBG was the first Ag-Ce co-doped MBG.

A pure tetragonal europium-doped yttrium-stabilized zirconia thermal barrier coating: Phase structure and luminescence

YSZ:Eu powder was prepared by sol spray pyrolysis method. Thermal barrier coatings (TBCs) composed of Eu3+-doped pure tetragonal yttrium-stabilized zirconia (namely, YSZ:Eu) were fabricated by air-plasma spraying technique. Crystal structure and fluorescence intensity of YSZ:Eu coating were investigated after aging at 1200 °C for 5 − 100 h. X-ray diffraction (XRD) indicates that tetragonal phase in YSZ:Eu coating had high resistance to degradation over a wide range of time periods and temperatures. Luminescence results indicate that asymmetry ratios of the fluorescence emission spectra were stable in a range of 1.2 ± 0.2. Relationships between phase structure and lattice distortion were further studied by fluorescence spectroscopy measurement using I606/I590 intensity ratio. The fluorescence results were consistent with those drawn by XRD, where the high stability of YSZ:Eu coating was confirmed. Excellent thermal stability, in terms of both the phase structure and luminescence intensity, of YSZ:Eu coating indicates that the present preparation method is suitable for phosphor powder applications.

Structural, optical, electrical and gas sensor properties of Fe-doped CdO thin films synthesized by spray pyrolsis

In this study, the structural, optical, electrical and gas sensor properties of Fe-doped CdO thin films synthesized using the spray pyrolysis method were investigated as a function of Fe doping. The characterizations of the thin films were made by using X-ray diffraction (XRD), X-ray photoelectron (XPS), ultraviolet–visible (UV-VIS), field emission-scanning electron microscope (FE-SEM), atomic force microscope (AFM) and Hall measurements. In addition, the response values of the films for H2 gas were determined by a current-sensitive gas sensor measurement system. XRD analyzes revealed that the produced films were in polycrystalline cubic structure and their unit cell volumes were reduced by Fe doping. The mean particle size and mean dislocation density of Fe doped samples were obtained as 11.99 nm and 6.98 × 1015 (line/m2), respectively. XPS results showed that the experimentally obtained doping ratios of the produced films were very close to the planned doping ratios and the formation of CdxFe(1-x)-O2 and CdxFe(1-x)-O3 on the surfaces of the samples decreased with the increment of Fe doping. UV-VIS measurements demostrated that the band gap is generally reduced due to doping, in line with the Moss-Burstein effect. According to Hall results, the mobility of the samples increases with increasing doping. SEM and AFM analyzes revealed that Fe doping to CdO causes nanoroads formation on thin film surfaces, and nanoroads disappear in 4 % and 5 % doped films. In addition to the specified characterizations, how these changes in the surface morphology of the films with Fe doping affect the H2 gas responses of the samples is also explained in the study.

Study of structural, optical and electrical properties of Nickel doped ZnO (Ni–ZnO) nanorods grown by chemical bath deposition

To investigate the effect of Nickel on ZnO thin films, doped ZnO (Ni–ZnO) thin films were synthesized using chemical bath deposition on seed layers which were first grown using the conventional spray pyrolysis method. Structural, optical and electrical properties were studied at different doping levels of Ni (0, 2, 4, 6, 8 %). All samples exhibited a highly defined (002) peak indicating a strong hexagonal crystal structure orientation. The samples showed a red shift at E2L and E2H Raman modes indicative of structural alterations. The undoped, 2 % and 4 % Ni doping levels showed lower mean roughness values compared to the 6 % and 8 % Ni doping. The Introduction of Ni into the ZnO structure appears to reduce the grain size from 167 nm to the lowest 79 nm at 2 % Ni concentration. Optical and electrical properties showed that the introduction of Ni as a dopant led to improved transmittance of up 70 % within the visible range and reduced resistivity from 3.590*10−3 (Ωcm) at undoped ZnO to 0.616*10−3 (Ωcm) 2 % Ni doped ZnO concentration.

Effect of precursors on structural, optical and surface properties of ZnO thin film prepared by spray pyrolysis method: efficient removal of Cu (II) from wastewater

Effect of precursors on structural, optical and surface properties of ZnO thin film prepared by spray pyrolysis method: efficient removal of Cu (II) from wastewater

Ag Incorporated MoO3 Thin Films and Fabrication of Ag/MoO3/p-Si Structured Photodiode

MoO3 have been widely investigated for their applications ranging from electronics to energy storage. Orthorhombic structured MoO3 thin films were prepared on a glass substrate. The Ag doped materials to add the MoO3 in different concentrations (1%, 3%, 5%) at Wt% with MoO3 precursor and synthesis was done using the spray pyrolysis method. X-ray diffraction revealed the incorporation of Ag in the MoO3 orthorhombic structure. FE-SEM images showed more dispersive and rod shapes than Agi-doped MoO3 and pure MoO3 respectively. The jet nebulizer spray pyrolysis technique for fabrication of n-Ag: MoO3/p-Si photodiodes makes it suitable for good response photo-detecting applications.

Analyses of Cu impurity effects on the USP grown MgO thin films: Structural, optical and photocatalytic assessments

Unspoiled and copper (Cu) doped magnesium oxide (MgO) thin films were successfully grown via ultrasonic spray pyrolysis method on soda lime glass substrates. Aftermath of the varied impurity presence in the host material were examined by conducting scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), photoluminescence (PL) spectroscopy, ultraviolet–visible (UV) spectroscopy, and photocatalytic measurements. The structural observations unveiled that the grown films showed (101) plane orientations with no secondary phases such as Cu or copper oxide present. Also, the XRD data discovered that the grain size of pure MgO sample decreased owing to the fact that Cu impurities introduced into the host material lattice system. In addition to that, the SEM images revealed that the impurity addition into the MgO nanocrystallites switched molecular shapes from regular to spherical structures. Besides, the aimed elemental compositions in the synthesized thin films were verified by the XPS. Furthermore, the photocatalytic measurements uncovered that the right amount of the magnesium content in the host material can enhance and tune the photocatalytic performance of the MgO films as desired. In the optical measurements, it was observed that optical absorbance values increased in the presence of varied percentages although these increments followed a random trend in respect to the doping levels (0.5%, 1%, 2%, 4% and 8 wt.%). The PL spectra revealed that the intensity of luminescent emissions gradually decreased which can be ascribed to the imperfections as a result of the introduced Cu into MgO.

An overview on spray pyrolysis deposition of metal oxide thin films

This work provided an overview on the synthesis of metal oxide thin films on different types of substrates (soda lime glass, fluorine-doped tin oxide glass, silica glass, stainless steel, quartz, silicon and microscopic glass slide) using spray pyrolysis method. The fundamentals, advantages and limitations of this method have been described. Experimental results indicated that the properties of films were strongly depending on the specific process parameters (nozzle type, distance between nozzle and substrate, solvent type, solution flow rate, precursor concentration, compressed air pressure, spray time and substrate temperature). It was noted that deposition temperature could control the surface chemical composition based on the experimental results. The presence of amorphous or polycrystalline structure could be observed for the films prepared at different deposition times as indicated in XRD studies. The obtained films indicated excellent absorption coefficient value (104 to 105 cm-1) and high transmittance value (more than 82 %) in the visible and infrared portion.