Thermal Treatment Step Research Articles

Terbium (III) and salicylamide doped nickel ferrite (NiFe2O4) nanoparticles synthesized from Olea europaea L. plant extracts via eco-friendly green synthesis approach and co-precipitation method

An eco-friendly and cost-effective NiFe2O4 nanoparticles and its derivatives NiFe2O4:salicylamide, NiFe2O4:salicylamide:Tb3+ and NiFe2O4:salicylamide:Tb3+:Olea europaea L. extracts have been successfully synthesized using a simple and refluxed-assisted chemical co-precipitation method and green route approach followed by thermal treatment steps. In this report, the structural, morphological, optical characteristics and biological activities of the nanoparticles were characterized by using XRD, SEM, FTIR, UV-Vis, PL, BET analysis, antibacterial assays and antioxidant activities. The results from XRD revealed that NiFe2O4 has a crystalline structure and EDX elemental mapping confirmed the uniform distributed of all the elements in the matrix. The incorporation of salicylamide, Tb3+ and Olea europaea L. extracts into NiFe2O significantly enriched the luminescence intensities and changed the emission colour coordinates. Colour tunability was achieved with luminescence ranging from bright blue emission to reddish orange light, which makes nanoparticles important candidates for solid-state lighting technologies. Combining olive leaf extracts with NiFe2O4 nanoparticles provided effective antioxidant and antibacterial activity by reducing and stabilizing of nanoparticles. Moreover, all experimental results reveal new ideas for the design and optimization of multifunctional nanomaterials with higher sensitivity and pave the way for the production of new functional nanomaterials.

Sustainable fabrication of solvent resistant biodegradable cellulose membranes using green solvents

The paradigm of the polymer industry is confronting an inevitable transition from fossil-based to bio-derived sources. The membrane-based separation process, generally regarded as a sustainable technology, mostly employs fossil-based polymeric membranes. In order to become an entirely carbon–neutral technology, all of the materials and chemicals employed during membrane fabrication must be scrutinized from a sustainability perspective. In this work, we report a versatile strategy to fabricate solvent-resistant cellulose membranes using bio-derived green solvents. The thermodynamic and kinetic aspects of the membrane fabrication process were systematically investigated. It was found that well-known green solvents such as Cyrene and PolarClean were not suitable due to high dope viscosity, whereas bio-derived methyl lactate and triethyl phosphate exhibited desirable properties to yield excellent cellulose membranes. The membrane performance could be tailored from the ultrafiltration to nanofiltration range by controlling the fabrication parameters. Importantly, the thermal treatment step prior to the deacetylation reaction was necessary to improve the solute rejection profile. The cellulose membranes displayed adequate compression resistance against pressure. However, their shear resistance was insufficient compared to that of commercial membranes. Nevertheless, the prepared cellulose membranes exhibited excellent solvent resistance in strong aprotic solvents such as N-methylpyrrolidone and N,N-dimethylacetamide, potentially allowing them to enter niche membrane markets such as the organic solvent nanofiltration (OSN).

Fluorescent Carbon Nitride Nanoparticles for Picric Acid Sensing.

Detection of nitroaromatic explosives is essential in the area of environmental safety. Fluorescent carbon nitride nanoparticles is a promising material for this purpose. Herein, we have prepared fluorescent carbon nitride nanoparticles (CNNPs) by one step thermal treatment of formamide. These fluorescent CNNPs is sensitive towards picric acid (PA) than other analytes both in aqueous medium and on test paper which is witnessed by fluorescence quenching based on inner filter effect (IFE). The PA detection with the fluorescent CNNPs is observed in the concentration ranges, 0 µM to 60 µM with linear range of 10 nM to 25 µM. The minimum detection limit in aqueous medium and solid phase are determined to be 26.20 nM and 10 µM respectively. Finally, the fluorescent CNNPs is applied for detection of PA in real water samples. The recoveries are in the ranges from 99.54 to 116.35% with relative standard deviation less than 3.85%. This proposed fluorescent method can act as suitable analytical technique to monitored PA concentration in water samples.

AMP, ADP, and ATP Concentrations Differentially Affected by Meat Processing, Manufacturing, and Nonmeat Ingredients

Given its presence in a wide spectrum of soils relevant to food process hygiene, the biological metabolite adenosine triphosphate (ATP) is used as a target for surface hygiene assessments in food processing facilities. Yet, ample evidence demonstrates that ATP is depleted into adenosine di- (ADP) and monophosphate (AMP) homologs resulting in a loss of sensitivity for ATP-based hygiene assays. Yet, there are few studies that denote the degree of these shifts under routine processing conditions such as those encountered during various meat processing steps that may likely alter redox potential and adenosine profiles (e.g., tissue/cellular disruption, application of reducing additives, fermentation, or thermal treatment steps). In this study, meat samples were collected from homogenized beef tissue treated with nonmeat ingredients (sodium chloride, sodium nitrite, sodium erythorbate, natural smoke condensate, and sodium acid pyrophosphate) during manufacture at predetermined steps, and from retail meat products purchased from local markets. Concentrations of ATP, ADP, AMP, and AXP (sum concentration of all homologs) in a lab setting and in situ meat processing venues were determined and compared. Greater differences in AXP were seen during manufacture, where ADP generally comprised ∼90% as a mole fraction of AXP across all treatments, with the exception of the final cook step where AMP predominated. ATP concentrations averaged 2 log values lower than ADP and AMP. Adenosine profiles in retail samples followed similar trends with minimal ATP concentrations with ADP predominant in uncooked samples and AMP predominant in cooked samples. Resultingly, meat processing steps during product manufacture will alter AXP-reliant test sensitivities which should be considered when such technologies are utilized for hygiene verification in meat processing.

Manufacturing Oxide Dispersion Strengthened (ODS) steel plate via cold spray and friction stir processing

Oxide dispersion strengthened (ODS) steels, traditionally fabricated by ball milling and conventional powder metallurgy techniques to achieve bulk form, followed by intricate rolling and thermal treatment steps to achieve plate or sheet form. Here, we present a novel processing route that combines cold spray (CS) with friction stir processing (FSP) to manufacture ODS steel plate directly from gas atomization reaction synthesis (GARS)-prepared powder, thus no rolling steps involved. Microstructural and mechanical characterizations were performed to assess the quality and properties of the resulting ODS steel plate. Our findings demonstrate that the slightly porous CS deposited layer was fully consolidated after FSP, yielding a fully dense ODS steel plate that exhibited a favorable tradeoff between strength and ductility upon extraction from the substrate. Furthermore, through microstructural analysis, we revealed the presence of an appreciable density (∼1022/m3) of nano-sized oxide particles, with the majority being smaller than 5 nm via the combined CS + FSP fabrication route. This work serves as a first proof-of-concept demonstration of the manufacturing approach described herein, offering a possible alternative route for producing ODS steel plates.

A synthetic strategy towards sulfonated all-aromatic polyamides and poly(benzoxazole-co-amides)

Herein, we describe the synthesis and properties of a liquid crystal all-aromatic polyamide with tunable sulfonated content that can be converted into its poly(benzoxazole-co-amide) analog using a simple thermal treatment step. The parent all-aromatic polyamide, poly(3,3′-dihydroxybenzidine terephthalamide) (DHTA), is modified by incorporating a sulfonated comonomer, 2,5-diaminobenzenesulfonic acid (DABS) (i.e., 5, 10, 25, and 50 mol% DABS), to yield sulfonated, random copolyamides (DHTA-y-DABS). The ortho-positioning of the hydroxyl group relative to the amide bond allows DHTA-y-DABS to undergo a cyclodehydration reaction from 200 to 450 °C, forming a sulfonated poly(benzoxazole-co-amide) while preserving the sulfonate functionalities. Swelling experiments show that the DHTA-y-DABS-Na+ films exhibit water uptake values ranging from 9 to 41 wt%. PBO-y-DABS-Na+ films swell between 4 and 15 wt% in water. Dry films exhibit excellent mechanical properties. Young's moduli are between 8 and 10 GPa, yield strength values range from 117 to 215 MPa and elongation at break values range from 3 to 10%.

A robust, scalable and adaptive wettability candle soot-modified fiber membrane for controllable oil–water mixtures/emulsion separation

Separation membranes with super-wettability are highly desirable for treating various oil/water contaminants. However, common fiber membranes suffer from single selectivity, poor stability and unsuitable pore structures, which cannot be easily modified to improve their separation performance in practice. Herein, an under-liquid superlyophobic fiber membrane (USFM) was prepared by a two-step approach, namely, spraying candle soot on an electrospun fiber membrane to form a rough structure and subsequently a thermal treatment step to improve stabilities. The obtained USFM-15 exhibits superamphiphilicity in air and under-liquid superlyophobicity after being pre-wetted by water and oil. With the synergy of suitable porosity and high selective wettability, the obtained membrane exhibited permeation fluxes of as high as 22,000 and 56,000 L m-2 h−1 with a separation efficiency of more than 99.5% for immiscible light/heavy oil/water mixtures. The USFM-15 also showed an excellent permeation flux for oil-in-water and water-in-oil emulsions of up to 4,000 and 20,000 L m-2 h−1, respectively. The separation efficiency of USFM-15 for emulsion was still more than 99.2% after 25 cycles. Moreover, the USFM-15 also has excellent reusability, high chemical stability and mechanical durability. The results of this study are expected to provide essential inspiration for designing, developing, and commercializing unique wetting materials.

Impurity analysis of electroplated gold components with multi-layered structures by thermal desorption spectrometry toward application in gold Micro electro mechanical system capacitive accelerometers

Au-based micro-electro-mechanical-system (Au-MEMS) capacitance accelerometers show high sensitivity by suppressing the mechanical noise because of the high mass density of gold (ρ = 19.3 g/cm3). On the other hand, their long-term reliability suffers from drift phenomena induced by the impurities incorporated in the key component during their fabrication process, such as the gold electroplating step. Herein, impurities in electroplated Au-based components for MEMS capacitive accelerometers are evaluated by thermal desorption spectrometry (TDS) measurements. The TDS measurement reveals that dominant desorption gases from the Au-based component are molecular hydrogen (H2) and water (H2O). These desorption gases are derived from impurities in the electroplated Au-based component, and the amount of these gases is significantly suppressed by a thermal treatment step. In conclusion, this study demonstrates that the electroplated Au-based component contains impurities originated from the fabrication process, and these impurities could be removed by a thermal treatment step.

Using KNbO3 catalyst produced from a simple solid-state synthesis method in a new piezophotocatalytic ozonation hybrid process

The present work reports the development and application of potassium niobate (KNbO3) as a catalyst in a novel hybrid piezophotocatalytic ozonation process aimed at wastewater remediation. Pure KNbO3 samples were produced through a simple solid-state synthesis using water-soluble ammonium niobate (V) oxalate hydrate (C4H4NNbO9·xH2O) as niobium source, employing different potassium precursors (KNO3, K2CO3, KOH, and C8H5KO4). The synthesis was also carried out using powdered niobium oxide as a precursor, aiming to evaluate the differences between the niobates obtained. The results achieved in this study show that all the niobates produced using ammonium niobate (V) oxalate hydrate were composed solely of the orthorhombic structure of KNbO3, while the materials synthesized using niobium oxide exhibited the rhombohedral structure of KNbO3 along with niobium-rich potassium niobates (K3Nb8O21, K2Nb4O21, and KNb3O8) and residual niobium oxide. This behavior was attributed to the enhanced chemical homogeneity derived from the synthesis using ammonium niobate (V) oxalate hydrate, which facilitated the reaction between the components during the thermal treatment step. Furthermore, the optical and morphological properties of the niobates were considerably influenced by the application of different potassium salts. Owing largely to its morphological and electrical properties, the material synthesized using potassium hydrogen phthalate displayed the highest photocatalytic activity in terms of methylene blue discoloration among the niobates produced using C4H4NNbO9·xH2O. Finally, the proposed piezophotocatalytic ozonation process was found to be a highly efficient strategy for the discoloration of methylene blue, as it successfully harnessed the synergy between the multiple mechanisms involving active radical generation toward the development of a highly promising hybrid advanced oxidation process.

A General Synthetic Route to High-Quality Perovskite Oxide Nanoparticles and Their Enhanced Solar Photocatalytic Activity.

The main limitations of current methods for synthesizing perovskite oxide (ABO3 ) nanoparticles (NPs), e.g., the high reagent costs and sophisticated equipment, the long time and high-temperature processing, or multiple post-processing and thermal treatment steps, hamper their full study and potential application. Here, we use a facile low temperature (50 °C) chemical bath synthesis and only one annealing step to successfully produce high phase purity and crystalline quality nano-shaped rare-earth-based REMO3 NPs (RE=La, Nd, Sm, Gd; M=Fe, Mn, Al). We also show the versatility of this approach by fabricating La0.7 Sr0.3 MnO3 solid solution and non-RE-based BiFeO3 perovskite. To assess the potential of the as-prepared REFeO3 and REMnO3 NPs, they are used for photocatalytic degradation of the norfloxacin antibiotic and show high efficiency. We believe this easy, robust, versatile, and general route for synthesizing ABO3 -based NPs can be further explored in the vast perovskite family and beyond.

A General Synthetic Route to High‐Quality Perovskite Oxide Nanoparticles and Their Enhanced Solar Photocatalytic Activity

AbstractThe main limitations of current methods for synthesizing perovskite oxide (ABO3) nanoparticles (NPs), e.g., the high reagent costs and sophisticated equipment, the long time and high‐temperature processing, or multiple post‐processing and thermal treatment steps, hamper their full study and potential application. Here, we use a facile low temperature (50 °C) chemical bath synthesis and only one annealing step to successfully produce high phase purity and crystalline quality nano‐shaped rare‐earth‐based REMO3 NPs (RE=La, Nd, Sm, Gd; M=Fe, Mn, Al). We also show the versatility of this approach by fabricating La0.7Sr0.3MnO3 solid solution and non‐RE‐based BiFeO3 perovskite. To assess the potential of the as‐prepared REFeO3 and REMnO3 NPs, they are used for photocatalytic degradation of the norfloxacin antibiotic and show high efficiency. We believe this easy, robust, versatile, and general route for synthesizing ABO3‐based NPs can be further explored in the vast perovskite family and beyond.

Improving porous properties of activated carbon from carbon gel by the OTA method.

High-surface-area microporous-mesoporous carbons were produced from carbon gel by applying the three consecutive steps of air oxidation, thermal treatment, and activation (the OTA method) to the gel. The formation of mesopores occurs both inside and outside the nanoparticles which form the carbon gel, while micropores are predominantly created within the nanoparticles. The OTA method offered a greater increase in pore volume and BET surface area of the resulting activated carbon in comparison with conventional CO2 activation either under the same activation conditions or at the same degree of carbon burn-off. Under the best preparation conditions, the maximum values of micropore volume, mesopore volume, and BET surface area achievable using the OTA method were found to be 1.19 cm3 g-1, 1.81 cm3 g-1, and 2920 m2 g-1, respectively at a 72% carbon burn-off. The larger increase in porous properties of activated carbon gel prepared by the OTA method over those based on conventional activation stems from the effects of the oxidation and heat treatment steps of the OTA method that could produce a large number of reaction sites which lead to efficient pore formation during the following CO2 activation process.

Zero-Waste Approach: Assessment of Aluminum-Based Waste as a Photocatalyst for Industrial Wastewater Treatment Ecology

Alum sludge (AS) is produced in inevitable amounts from drinking water treatment plants. Also, dye-contaminating wastewater is usually discharged from textile industries that must be treated to meet the environmental authorities; thus, Fenton’s reagent is a suitable candidate. However, reducing the quantity of chemicals used in Fenton reactions can be partly achieved by an industrial ecology approach. This paper is introducing alum sludge waste as a photocatalyst, (termed as AS-Fenton), that is prepared under mild experimental conditions. Thermogravimetric and differential thermogravimetric analyses were conducted to attain full illustrations of the thermal treatment steps. Its chemical composition and morphology is revealed using X-Ray Diffraction and Scanning Electron Microscope. Thus, this research is of great significance for the application of a waste by-product for being a Fenton source for photocatalytic removal of Levafix Blue dye effluent. A new modified Fenton reagent was applied with the addition of 1.0 g/L and 800 mg/L of catalyst and H2O2, respectively, at pH 3.0 shows high potential for the dye removal. The starting concentration of the Levafix Blue CA was halved during the first 5 min under the UV illumination. The most effective operating variables are optimized through Response Surface Methodology. The kinetics of the dye removal was investigated and the reaction following the pseudo-first-order regime with the kinetic constant (KF), ranged in 0.04–0.57 min−1. Thermodynamic parameters reveal that the reaction is a non-spontaneous and endothermic in nature. Hence, toxicity of the dye is significantly reduced via Fenton reaction to non-toxic end products.

Cross‐Linking of Biobased Monofunctional Furan Epoxy Monomer by Two Steps Process, UV Irradiation and Thermal Treatment

AbstractAmong the new generation of green polymers, furan monomers are occupying a strategic role to produce both innovative biobased thermoplastic and thermoset. Herein, furfuryl glycidyl ether (FGE) is used as monomer to design two steps cured coating. Linear polymer chains are first produced by means of cationic UV technique. The UV reactivity of FGE is assessed by real‐time Fourier Transform Infrared Spectroscopy (FTIR). Then, a thermal treatment is carried out to crosslink the UV‐irradiated linear chains. The formation of cross‐links is proven by means of different techniques. ATR‐FTIR shows the development of new chemical bonds by the appearance of new bands. Differential scanning calorimetry analysis confirms the cross‐link reaction by the presence of exothermic peaks and the dynamic mechanical thermal analysis reveals an increase of the Tg as direct consequence of cross‐links formation. Moreover, the %gel analysis confirms the formation of highly insoluble fraction after the cross‐linking.

Noble metals Pt, Au, and Ag as nucleating agents in BaO/SrO/ZnO/SiO2 glasses: formation of alloys and core\u2013shell structures

Noble metals such as Ag can be used as nucleation agents in glass ceramics. In glasses, it is incorporated predominantly as AgI. At temperatures slightly above the glass transition temperature, Tg, AgI reacts with SbIII to SbV and metallic Ag. Usually, face-centered cubic Ag particles are nearly spherical and get facetted during crystal growth. By contrast, in the case of BaO/SrO/ZnO/SiO2 glasses, silver has, in comparison to other noble metals, another significant, yet different effect. It forms metallic particles (hexagonal phase) with plate-like morphology during thermal treatment at 675 °C. In the second step of thermal treatment at 760 °C, this phase most probably expels some metallic Sb, which is oxidized by SbV (present in the surrounding glass phase) to SbIII. As a result, the plate-like morphology is maintained and a crystalline shell around the metallic core is formed, mainly consisting of ZnO with some SiO2 and antimony oxide, as proved by scanning transmission electron microscopy combined with energy-dispersive X-ray spectroscopy. This shell triggers the volume crystallization of Ba0.5Sr0.5Zn2Si2O7, a phase with low thermal expansion. By comparison, alloying of Au with Sb does not occur according to the phase diagram. Instead, a thermal treatment at temperatures slightly above Tg leads to nanocrystalline, spherical Au particles. Hence, alloying and subsequent decomposition of the alloy is a prerequisite for the formation of plate-like noble metal particles.

Enabling lightweight polycarbonate-polycarbonate (PC-PC) photovoltaics module technology – Enhancing integration of silicon solar cells into aesthetic design for greener building and urban structures

Light weight photovoltaic (PV) modules have advantages both to reduce costs of PV installations as well as to enhance their further integration with building and other urban structures such as roofs of public parking areas and bus stations. Polycarbonate (PC) materials have been studied before as glass or front sheet replacement, but recently the PC-PC module design (where both front and back sheets are made of PC) has gained attractions both in industry as well as in research. It offers further additional benefits, such as improved reliability (in terms of silicon cell cracks) and enhanced ease of integration into not only flat surfaces, but also curved ones such as integrated PV in cars, trucks, and boats. These benefits may enable more aesthetic design that can increase the appeal of the PV technology. However, a few technological issues stand between the current forms of PC-PC PV module design and the increasing market demands for more aesthetically pleasing and contour-confirming PV integrations. Two of the most important ones are the silicon sensitivity against fracture (especially in bending mode) and interface delamination (especially between PC and the encapsulants). Both are driven by mechanical stresses in the silicon cells as well as in other materials in the PV module/package design. Having published widely our studies in stresses in silicon solar cells in PV module design, both experimentally as well as computationally as shown in the literature review of this manuscript, our research group has obtained unique insights in the primary driving forces of failures in the typical PV module design (glass-back sheet). In the present manuscript, we use the Width Tapered Cantilever Beam (WTCB) method to investigate the interfacial delamination issues systematically. We found that the energy release rate for delamination or fracture at the interfaces between PC and EVA (Ethylene Vinyl Acetate) was fairly low (i.e. low adhesion strength), but could be enhanced with process parameters during the PV lamination step or separate thermal treatment. Hence, this could be taken advantage for enabling unique and highly innovative PV modules based on PC, and for aesthetic purposes for the wider applications of PV technology.

Superparamagnetic and highly bioactive SPIONS/bioactive glass nanocomposite and its potential application in magnetic hyperthermia

Magnetic bioactive glass-ceramics are biomaterials applied for magnetic hyperthermia in bone cancer treatment, thereby treating the bone tumor besides regenerating the damaged bone. However, combining high bioactivity and high saturation magnetization remains a challenge since the thermal treatment step employed to grow magnetic phases is also related to loss of bioactivity. Here, we propose a new nanocomposite made of superparamagnetic iron oxide nanoparticles (SPIONs) dispersed in a sol-gel-derived bioactive glass matrix, which does not need any thermal treatment for crystallization of magnetic phases. The scanning and transmission electron microscopies, X-ray diffraction, and dynamic light scattering results confirm that the SPIONs are actually embedded in a nanosized glass matrix, thus forming a nanocomposite. Magnetic and calorimetric characterizations evidence their proper behavior for hyperthermia applications, besides evidencing inter-magnetic nanoparticle interactions within the nanocomposite. Bioactivity and in vitro characterizations show that such nanocomposites exhibit apatite-forming properties similar to the highly bioactive parent glass, besides being osteoinductive. This methodology is a new alternative to produce magnetic bioactive materials to which the magnetic properties only rely on the quality of the SPIONs used in the synthesis. Thereby, these nanocomposites can be recognized as a new class of bioactive materials for applications in bone cancer treatment by hyperthermia.

Energy-efficient thermal waste treatment process with no CO2 emission: A case study of waste tea bag

Everyday waste is a serious matter of concern because of its disruptive impact on the environment. Although disposal and reclaim of such material represent the first lines of intervention to solve this problem, upcycling strategies should eventually be necessary to reconvert huge amounts of the waste. In addition to waste, climate change caused by greenhouse gas emissions (e.g., carbon dioxide (CO2)) is other global environmental problem. Here, we employed a thermal treatment process conducted in CO2 environment to upcycle waste tea bag (a surrogate feedstock for everyday waste) and utilize CO2 simultaneously. Through lab-scale experiments, 6 wt% caprolactam (a value-added nylon monomer), 12.7 wt% combustible gases (higher heating value (HHV): 24.8 MJ kg−1), and 13.8 wt% char (HHV: 28.1 MJ kg−1) were obtained at 500 °C. Based on the experimental results, a large-scale energy analysis of the process was conducted by developing a simulation model of an integrated process to produce caprolactam-rich liquid product. For the integrated process, CO2 in gaseous product mixture is separated, and the separated CO2 is recirculated to the thermal treatment step. The combustible gases and char are used to supply energy to thermal treatment and separation steps. The proposed process has a significant feature that there is no need for external energy with no CO2 emission (i.e., CO2 is fully recirculated in the waste treatment process).

Evaluating volume reduction of clarified acid bovine milk whey via falling film vacuum evaporation

This research evaluates the effect of falling film vacuum evaporation on the characteristics of clarified acid bovine milk whey. The clarified acid whey was obtained by microfiltration (ceramic membranes, 0.2 µm cut-off, ∆TMP: 2 bar) and concentrated by a falling film evaporator. The clarified whey composition was mainly protein (0.32 ± 0.06 % w/w), ashes (0.56 ± 0.08 % w/w), soluble solids (5 ± 1 % w/w), and turbidity (16 ± 5 NTU). During the concentration step, the number of cycles changed notoriously for each volume reduction factor (VRF), being four the highest value achieved, with an average number of cycles of 18. The characteristics of concentrates were not affected by differences in the number of cycles, increasing proportionally with the VRF; it could be noticed in the final content that protein, ashes, and °Bx increased linearly around 3.5 times the initial composition. However, turbidity was different for each VRF because of heat treatment during the concentration stage (above 60 °C). A thermal treatment step after ricotta preparation would be advisable to remove the remaining protein. Tukey’s test was carried out at a 95 % CI, revealing statistical differences among means; therefore, there was a change in the characteristics of the final concentrated whey. Regarding color (absorbance), there were no considerable changes during the concentration process.

Creating electronic and ionic conductivity gradients for improving energy storage performance of ruthenium oxide electrodes

Robust Ru-based thin films are successfully fabricated by single- (SA) and multiple-annealing (MA) thermal decomposition methods and are utilized as high-performance electrodes for the supercapacitors. Two critical parameters, the annealing temperature and treatment duration, are engineered for synthesizing stable thin-film electrodes. It is found that the SA thermal decomposition technique at 250 °C for 6 h results in stable RuO2 electrodes with remarkable electrochemical performance. The MA approach consists of 2- and 3-stage thermal treatment steps. The maximal capacitance of MA-treated capacitor reaches as high as 308.8 F g−1. The MA-treated electrodes deliver exceptional rate capability as well as superior cycling stability (93% capacitance retention upon 2000 cycles). The enhanced performance is attributed to the multistep thermal stages along with the layer-by-layer deposition, enabling enhanced heat transfer to individual thin layers. An optimal thermal treatment procedure is assessed empowering enhanced capacitive performance due to high hydrous RuO2·xH2O ratio, reduced crystalline structure, facile electrolyte wetting, and stable adhesion between the deposits and the Ti substrate. The robust design of MA-treated thin film deposits paves the way for synthesizing high-performance electrodes for the supercapacitors.