Facile Spray Pyrolysis Method Research Articles

Single-Step Fabrication of BiOI Nanoplates as Gas Diffusion Electrodes for CO2 Electroreduction to Formate: Effects of Spray Pyrolysis Temperature on Activity and Flooding Propensity.

Bismuth-based electrocatalysts for carbon dioxide (CO2) reduction are notable for their high formate selectivity, scalability, affordability, and low toxicity. Here, we introduced a facile spray pyrolysis method to fabricate catalyst-coated gas diffusion electrodes (GDE) in one step. Our study revealed that deposition temperatures significantly affected the morphology, crystal orientation, and impurity of bismuth oxyiodide (BiOI) nanoplates. Specifically, BiOI prepared at 250 °C (BiOI-250) exhibited exceptional Faradaic efficiency (>90%) for formate production at a high current range (100-300 mA cm-2) and demonstrated outstanding stability (>30 h). In situ Raman spectroscopy indicated that BiOI-250's superior performance stemmed from its resilience to microscopic flooding, a failure mechanism observed in low-temperature BiOI. X-ray absorption spectroscopy (XAS) showed that BiOI-250 predominantly consisted of the active Bi2O2CO3 phase, while low-temperature BiOI contained a mixture of Bi2O2CO3 and the less active Bi metal, formed via the reduction of the Bi2O3 impurity. This impurity led to increased catalyst resistivity, uneven potential distribution, and restructuring, contributing to flooding. Our study underscores the crucial role of catalyst structures in determining electrode performance and flooding propensity, offering key insights for optimizing bismuth-based electrocatalysts for CO2 reduction.

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.

Boosting photoelectrochemical water splitting of bismuth vanadate photoanode via novel co-catalysts of amorphous manganese oxide with variable valence states

Bismuth vanadate (BVO) is a promising photoanode while suffers from sluggish oxygen evolution kinetics. Herein, an ultra-thin manganese oxide (MnOx) is selected as co-catalyst to modify the surface of BVO photoanode by a facile spray pyrolysis method. The photoelectrochemical measurements demonstrate that surface charge transport efficiency (ηsurface) of MnOx modified BVO photoanode (BVO/MnOx) is strikingly increased from 6.7 % to 22.3 % at 1.23 VRHE (reversible hydrogen electrode (VRHE)). Moreover, the ηsurface can be further boosted to 51.3 % at 1.23 VRHE after applying Ar plasma on the BVO/MnOx sample, which is around 7 times higher comparing with that of pristine BVO samples. Additional characterizations reveal that the remarkable PEC performance of the Ar-plasma treated BVO/MnOx photoanode (BVO/MnOx/Ar plasma) could be attributed to the increased charge carrier density, extended carrier lifetime and additional exposed Mn3+ active sites on the BVO surface. This investigation could provide a new understanding for the design of BVO photoanode with superior PEC performance based on the modification of MnOx and plasma surface treatment.

Facile Fabrication of CeO2-Al2O3 Hollow Sphere with Atomically Dispersed Fe via Spray Pyrolysis.

A facile spray pyrolysis method is introduced to construct the hollow CeO2-Al2O3 spheres with atomically dispersed Fe. Only nitrates and ethanol were involved during the one-step preparation process using the ultrasound spray pyrolysis approach. Detailed explorations demonstrated that differences in the pyrolysis temperature of the precursors and heat transfer are crucial to the formation of the hollow nanostructure. In addition, iron species were in situ atomically dispersed on the as-formed CeO2-Al2O3 hollow spheres via this strategy, which demonstrated promising potential in transferring syn-gas to valuable gasoline products.

Lithium-antimony co-doping induced morphology transition in spray deposited SnO2 thin films

Un-doped, Sb doped (ATO) and Li-Sb co-doped SnO2 (LATO) transparent conducting thin film electrodes have been deposited using facile spray pyrolysis method. X-ray diffraction study is carried out to confirm the crystal structure, phase purity, and textured growth of the films. Surface morphological transition from dendritic to cuboid shape is observed upon Li-Sb co-doping into the SnO2 system from the scanning microscopy measurements. The AFM analysis confirms that as Li doping concentration (1, 3, 5 wt.%) increases, the surface roughness of the films decreases. The UV-Vis transmittance spectra of the SnO2 film doped with 5 wt.% Li and 5 wt.% Sb (LATO5) shows maximum average transmittance of 87.9 % at 550 nm and the calculated direct band gap value is 4.06 eV. The LATO5 film exhibits high carrier concentration and high mobility of 7.54 × 1020 cm−3 and 7.221 cm2/Vs, respectively, due to co-dopant effect at the Sn sites of SnO2 lattice, resulting in enhanced electrical transport properties compared to un-doped SnO2 film. The LATO5 film also exhibits lowest sheet resistance of 32.38 Ω/□ and resistivity of 1.57 × 10−3 Ω cm. The temperature dependent electrical conductivity study is performed to understand the conduction mechanism of the film via estimation of activation energy from Arrhenius plots. The obtained results indicate that the Li-Sb co-doped SnO2 films are potential candidates for alternative transparent conducting electrode system.

Passion fruit-like structure endows Li3V2(PO4)3@C/CNT composite with superior cyclic stability and rate performance

Monoclinic Li3V2(PO4)3 (LVP) fulfills safety requirements including superior chemical and thermal stabilities since the oxygen atoms are firmly anchored in PO43− units, however the low intrinsic electronic conductivity strictly limits its electrochemical performance. Herein, to overcome this problem, a rationally designed passion fruit-like LVP@C/CNT composite constructed with LVP grains as seeds, carbon matrix as pulp, and carbon nanotubes (CNTs) as filaments, has been prepared via a facile spray pyrolysis method. In such unique biomimetic structure, carbon matrix encases LVP to reduce its particle size, which is beneficial to shorten ion pathways; Porous structure scattered around carbon matrix facilitates the rapid penetration of electrolyte; 3D CNT networks afford high-speed electron conduction and remarkable structural stability by forming the bridges between LVP grains. Owing to the multiple merits of this biomimetic structure, the rationally designed LVP@C/CNT composite with 3 wt% CNT exhibits high reversible capacity, superior cyclic stability and remarkable rate capability.

Large-area spray deposited Ta-doped SnO2 thin film electrode for DSSC application

Large-area (10 × 10 cm2) Ta-doped SnO2 (TTO) thin film was deposited by a facile spray pyrolysis method. The crystallinity, phase purity, and texture properties of the film are studied using XRD analysis. The XPS study confirmed the charge state of Sn to be in 4+, O1s in 2−, and Ta to be in 5+ state. A homogeneous polyhedron morphology was witnessed owing to the Ta dopant effect. The TTO film was highly transparent in the visible to near infrared region (NIR) with an average transmittance value of 81% at 550 nm. The TTO film was having a free carrier concentration of 5.42 × 1021 cm−3 and mobility of 41.7 cm2/Vs. The 4 wt% Ta doped SnO2 electrode exhibits a low sheet resistance of 26 Ω/□ and a high figure of merit value of 6.15 × 10−3 Ω−1. The resistance stability of sheet resistance was fairly good up to 400 °C indicating suitability of the TTO electrode to serve as conducting photoanode/counter electrode in dye-sensitized solar cell (DSSC) device. The DSSC device fabricated with the TTO electrode exhibited appreciable efficiency of 3.26% which is attributed to the enhanced electrical and optical properties by way of doping with Ta element.

Synthesis of chemical spray pyrolyzed Cu2FeSnS4 thin films for solar cells

In this paper, we have successfully prepared Cu2FeSnS4 (CFTS) thin films by a facile spray pyrolysis method. In order to optimize the synthesis conditions of the CFTS thin films, two series of experiments were performed. In the first series, the thin films were deposited at a substrate temperature of 370 °C for different spray durations (td) of 20, 40 and 60 min. And in the second, the CFTS thin films were annealed in the sulfur atmosphere at a temperature of 450 °C for 30 min. Moreover, the X-ray diffractograms showed that the as-deposited and the post-annealed CFTS thin films revealed a stannite structure. The post-annealed CFTS thin films are considered as an ideal absorber in solar cells because of a large absorption coefficient (105 cm−1) and a direct band gap (1.55 eV). The activation energies Ea obtained from both angular frequency and DC conductivity are found to be 1 and 0.97 eV, respectively.

Structural and Solar Cell Properties of a Ag-Containing Cu2ZnSnS4 Thin Film Derived from Spray Pyrolysis.

A silver (Ag)-incorporated kesterite Cu2ZnSnS4 (CZTS) thin film was fabricated by a facile spray pyrolysis method. Crystallographic analyses indicated successful incorporation of various amounts of Ag up to a Ag/(Ag + Cu) ratio of ca. 0.1 into the crystal lattice of CZTS in a homogeneous manner without formation of other impurity compounds. From the results of morphological investigations, Ag-incorporated films had larger crystal grains than the CZTS film. The sample with a relatively low Ag content (Ag/(Ag + Cu) of ca. 0.02) had a compact morphology without appreciable voids and pinholes. However, an increase in the Ag content in the CZTS film (Ag/(Ag + Cu) ca. 0.10) induced the formation of a large number of pinholes. As can be expected from these morphological properties, the best sunlight conversion efficiency was obtained by the solar cell based on the film with Ag/(Ag + Cu) of ca. 0.02. Electrostructural analyses of the devices suggested that the Ag-incorporated film in the device achieved reduction in the amounts of unfavorable copper on zinc antisite defects compared to the bare CZTS film. Moreover, the use of a Ag-incorporated film improved band alignment at the CdS(buffer)-CZTS interface. These alterations should also contribute to enhancement of device properties.

Crumpled rGO-supported Pt-Ir bifunctional catalyst prepared by spray pyrolysis for unitized regenerative fuel cells

Three-dimensional (3D) crumpled reduced graphene oxide supported Pt-Ir alloys that served as bifunctional oxygen catalysts for use in untized regenerative fuel cells were synthesized by a facile spray pyrolysis method. Pt-Ir catalysts supported on rGO (Pt-Ir/rGOs) were physically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) to observe change in composition by heat treatment, alloying, and morphological transition of the catalysts. Their catalytic activities and stabilities for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) conditions were electrochemically investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), potential cycling and hold tests on the rotating disk electrode (RDE). Pt-Ir/rGO with no post heat-treatment (Pt-Ir/rGO_NP) showed a lower activity for ORR and OER although metal nanoparticles decorated on the support are relatively small. However, Pt-Ir/rGO showed remarkably enhanced activity following heat treatment, depending on temperature. Pt-Ir/rGO heat-treated at 600 °C after spray pyrolysis (Pt-Ir/rGO_P600) exhibited a higher activity and stability than a commercially available Pt/C catalyst kept under the ORR condition, and it also revealed a comparable OER activity and durability versus the commercial unsupported Ir catalyst.

A facile spray pyrolysis method to prepare Ti-doped ZnFe2O4 for boosting photoelectrochemical water splitting

A facile spray pyrolysis method was used to prepare high-performance Ti-doped ZnFe2O4 for boosting photoelectrochemical water splitting.

α-MoO3-C composite as counter electrode for quantum dot sensitized solar cells

Counter electrodes plays a vital role in electron transport in operation of QDSSCs. The lower charge transfer resistance at counter electrode - electrolyte interface fecilitates improvement in photoconversion efficiency. The present study describes a novel and facile Spray Pyrolysis method for fabrication of low cost α-MoO3-Carbon composite (α-MoO3–C) material which is used as counter electrode (CE) in QDSSCs. The QDSSC with TiO2 photoanode sensitized by cadmium sulphide (CdS) QDs and polysulfide as electrolyte and α-MoO3-C composite as counter electrode exhibited solar energy-to-electricity conversion efficiency of 1.29%, which is better than those of the cells that used platinum and Cu2S as counter electrodes. QDSSCs with α-MoO3-C composite used as counter electrode gives stable and reproducible performance. The improvement in efficiency with α-MoO3-C composite Counter electrode was mainly driven by the improvement in photocurrent density and decrease in charge transfer resistance at counter electrode – electrolyte interface. Electrochemical impedence spectroscopy studies are carried out to understand electron transport in the device at various interfaces. α-MoO3-C composite has shown more electrocatalytic response for the reduction of redox species of the polysulfide than platinum and Cu2S.

Morphological Modification of TiO₂ Thin Films as Highly Efficient Photoanodes for Photoelectrochemical Water Splitting.

TiO2 films with modified morphology have been successfully synthesized via a facile spray-pyrolysis method in the presence of poly(ethylene glycol) (PEG) as a templating agent. The effects of the PEG concentration on the relevant properties of TiO2 films were investigated by means of scanning electron microscopy, X-ray diffraction, and UV-vis absorbance spectroscopy, while their photocatalytic properties were assessed by photoelectrochemical (PEC) water-splitting measurements. The introduction of 10 g·L(-1) PEG into the precursor solution leads to surface roughening with an exceptional improvement in PEC responses, revealing a photoconversion efficiency of 1.15% at -0.50 V vs HgO|Hg (in a 1 M NaOH electrolyte under broad-spectrum illumination), which is nearly triple that of the unmodified film (0.45% at -0.38 V vs HgO|Hg). Although the efficiency of the rough-surface photoanodes deteriorates upon increasing the PEG content, their PEC responses are still superior to those of smooth-surface films. Possible phenomena that might be responsible for the experimental observations are suggested and discussed accordingly.

Carbon nanosphere adsorbents for removal of arsenate and selenate from water

Carbon nanospheres prepared using a facile spray pyrolysis method display good adsorption to arsenate and selenate compared to commercial activated carbon, due to the presence of basic surface groups, high surface-to-volume ratio, and suitable microporous structure.

Influence of substrate temperature on ethanol sensing properties of CdO thin films prepared by facile spray pyrolysis method

Transparent conducting CdO thin films were deposited on to glass substrates by spray pyrolysis technique. The depositions were carried out at different substrate temperatures with varying film thickness. The effects of substrate temperature on structural, optical and electrical properties of CdO thin films were systematically studied. The CdO films were polycrystalline in nature with cubic crystal structure showing preferential orientation along (111) direction. Wettability results confirmed that the hydrophobic character of CdO thin film is enhanced with increase in substrate temperatures. The average transmittance is about 80 %, thus the films are transparent in the visible region. The optical band gap value of the CdO films increased from 2.24 to 2.34 eV with increase in the substrate temperature from 200 to 350 °C. Surface morphology studies reveal that the grain size and roughness of the films are increased with increase in the substrate temperature. The minimum value of electrical resistivity of the films is 1.40 × 10−3 Ω cm obtained at 350 °C. The maximum ethanol sensitivity of 33.45 % is observed for the substrate temperature of 300 °C. Thus the results authenticate that the substrate temperature influences the structural, optical, electrical and sensing properties of the deposited films.

Self-Organized Macroporous Carbon Structure Derived from Phenolic Resin via Spray Pyrolysis for High-Performance Electrocatalyst

The synthesis and evaluation of porous carbon derived from phenolic resin using a fast and facile spray pyrolysis method has been studied for use as a new electrocatalyst support material. By adding polystyrene latex nanoparticles as a template to the phenolic resin precursor, self-organized macroporous carbon structure was first developed. The mass ratio of phenolic resin to PSL at 0.625 gave the optimum porous morphology. Pt nanoparticles (∼20 wt %) were grown on the carbon surface using a standard industrial impregnation method. Well-dispersed Pt nanoparticles of average size 3.91 nm were observed on the surface of porous carbon particles. The high catalytic performance of porous Pt/C electrocatalyst was confirmed by the high mass activity and electrochemically active surface area, which were 450.81 mA mg(-1)-Pt and 81.78 m(2) g(-1)-Pt, respectively. The porous Pt/C catalyst obtains two times higher mass activity than that of the commercial Pt/C catalyst and performs excellent durability under acid conditions.