Calcination Temperature Research Articles

Elevated asymmetric supercapacitor with the nickel-metal organic framework derived nickel oxide/nickel composite: Designed to optimize efficiency and reliability

In this study, a solvothermal method is used to synthesizes MOF-derived NiO/Ni composites and NiO samples at various calcination temperatures (350 °C, 450 °C, 550 °C, and 650 °C) and durations (4, 5, 6, and 7 h). The NiO/Ni sample calcined at 450 °C for 5 h (NiO/Ni-450) exhibits the highest specific capacitance (Cs) of 410 Fg⁻¹ at a scan rate of 5 mV s⁻¹. This superior performance results from the combined benefits of Ni's metallic conductivity and NiO's redox activity. In a 1 M KOH electrolyte, NiO/Ni-450 retains about 83 % of its initial capacitance after 2,000 cycles. The NiO sample formed by calcining NiO/Ni-450 for 5 h (H5) achieves a specific capacitance (Cs) of 371 Fg⁻¹ and retains 80 % of its capacitance after 2,000 cycles. NiO/Ni-450 and H5 demonstrate energy densities (Ed) of 8.58 and 5.48 Wh kg⁻¹, and power densities (Pd) of 608 and 500 W kg⁻¹, respectively. An asymmetric supercapacitor using NiO/Ni-450 and activated carbon (AC) shows an impressive 80 % capacitance retention after 9,000 cycles, with a Cs of 123 Fg⁻¹, and Ed and Pd values of 14.58 Wh kg⁻¹ and 4038 W kg⁻¹, respectively, highlighting the potential for industrial-scale production of these materials for energy storage.

Research on the Influence of Thermal Decomposition of Magnesium Chloride Hexahydrate on the Preparation of Magnesium Oxide and Hydrated Magnesium Hydroxide

Magnesium chloride hexahydrate is an important intermediate product in magnesite processing. In order to promote the efficient utilization of magnesite resources, based on the pyrolysis interval of magnesium chloride hexahydrate, the relationship between magnesium oxide with different physicochemical properties and the apparent properties of hydrated magnesium hydroxide was studied. The results show that the effect of temperature on magnesium oxide sintering is stronger than that of holding time. With the increase of calcination temperature and the extension of holding time of magnesium chloride hexahydrate, the calcined product magnesium oxide was sintered into large particle size with the characteristic particle size D<sub>50</sub> of 33.89 μm. The crystal was distorted, the chemical activity deteriorated, and the color development time was up to 407 s. When hexahydrate magnesium chloride was calcined at 480 °C with 2 h, it decomposed almost completely. The product, magnesium oxide, consisted of uniformly distributed small coral rod-like particles with strong chemical reactivity and a color development time of 115 s. The particles were small and evenly distributed, with a characteristic particle size D50 of 1.36 μm, and the highest specific surface area reached 7.292 m<sup>2</sup>/g. The hydrated magnesium hydroxide particles had well-defined edges and corners, with a characteristic particle size D50 of 1.59 μm and a uniform particle size distribution.

Biochemical, toxicological, and microbiological assessment of calcined poultry manure for potential use as bone scaffold material

The biosafety of thermally calcined poultry manure as a hydroxyapatite source for potential use as bone-making material was investigated in this study. In vitro assays were used to determine the sensitivity of the antioxidant properties to the thermal calcination temperature used to process the poultry manure (750, 800, and 850 °C). The effect of the extract of both calcined poultry manure (local) and analytical grade hydroxyapatite (foreign) at various concentrations of 100%–25 % inclusion at (100 mg/kg) body weight intubation for 21 days on kidney, liver, and serum of animal model used was assessed. The results show that the thermally calcined poultry manure-derived hydroxyapatite generally possessed good antioxidant properties with the poultry manure treated at 750 °C having the most promising antioxidant properties compared to those treated at 800 and 850 °C, and hence a more likely improved anti-toxicity potential. The various blends of the analytical high-grade hydroxyapatite and thermally calcined poultry manure hydroxyapatite samples are safe compared to the normal control rats with regards hepatic function and renal function parameters with the equal blend of analytical high grade and thermally calcined poultry manure-derived hydroxyapatite (1:1) possessing the lowest activity concentrations. In addition, the enzymatic (glutathione peroxidase) and non-enzymatic (reduced glutathione) antioxidant concentrations of the experimental animals administered the varied compositions of the analytical high grade and thermally calcined poultry manure-derived hydroxyapatite, were lower when compared to normal control rats. The microbiological evaluation suggests that the calcined poultry manure inclusion at various concentrations could not pose a negative effect on various pathology in the liver, kidney, and blood.

Exploring the Synthesis of Novel Sillenite Bi12SnO20: Effect of Calcination Temperature on the Phase Formation and Catalytic Performance

Sillenite materials have been the focus of intense research in recent years due to their unique properties and distinct structure with the I23 space group. This electronic structure has reflected high-quality applications and results for some environmental processes such as photocatalysis. This paper investigates the synthesis of a new sillenite, Bi12SnO20, and its characteristics, emphasizing its potential for photocatalytic applications. The sillenite Bi12SnO20 has been synthesized through the co-precipitation method by mixing the appropriate ratio of Bi and Sn ions. The obtained particles after precipitation and drying were characterized by thermogravimetric analysis (TGA) and then calcined at different temperatures based on this analysis. The phase has been identified by structural analysis using X-ray diffraction (XRD), and its morphology after identification was carried out by scanning electron microscopy (SEM). The calcination temperature has been found to have a critical role in obtaining the phase, where the phase was found to be formed at temperatures between 310 and 400 °C and changed to other phases within higher temperatures. The physicochemical properties of this sillenite were also studied by Fourier-transform infrared spectroscopy (FTIR) and UV Visible Spectrometer (UV-Vis). To study the obtained phases at different calcination temperatures, performance testing was performed under visible light to remove different contaminants, which are Tetracycline, Bisphenol A, and Rhodamine B. The phase Bi12SnO20 obtained at 350 °C with a catalyst dose of 1 g/L showed the highest performance for removing these pollutants with concentrations of 20 mg/L, with an efficiency of almost 100% within 2 h. This work will be useful as an important resource and strategy for the development of this sillenite material in its pure phase.

Preparation of slag-based alkali-activated high-temperature-resistant (600–800 °C) metal interface bonding materials by modulating CaCO3 particles

In this study, an alkali-activated binders (AABs) with excellent high-temperature performance on the surface of iron plate was prepared by using alkali-activated slag as the main material, modulating the addition of filler CaCO3 particles (CC), and using iron plate (Q235) as the coated substrate. Through characterization and analytical tests such as compressive/flexural/bond strength, XRD, TG/DSC, SEM/EDS and OM, the results showed that the bonding effect between AABs and Q235 was mainly influenced by both the internal stress of AABs and the diffusion effect of the interfacial atoms. Under the condition of not adding CC, the internal stress of AABs was much larger than the interfacial bonding force, thus causing warping and spalling at room temperature. Microscopic characterization revealed that the addition of CC reduced internal stresses and microcracks, resulting in improved interfacial bonding. Excellent bonding properties were obtained by adding 10 g of CC, with a compressive/flexural/bond strength of 6.98/0.68/0.10 MPa, and a linear shrinkage of 2.22 % after calcination at 700 °C. The crystalline transition from CaCO3 and calcium silicate hydrate to akermanite-gehlenite, merwinite and lime does not begin to take place until the calcination temperature reaches 800 °C. The failure mechanism of AABs at room temperature and high temperature was studied to provide a basis for the optimization of existing AABs and the development of high-performance AABs.

Fabrication of temperature-regulated sorbitol/mannitol-doped copper oxides derived from a Cu complex and their photocatalytic properties

In this study, a series of composites containing copper oxide (CuxO) particles doped with sorbitol/mannitol, namely Cu/CuxO@C (x = 1 or 2), was successfully derived from a novel copper complex ([Cu(IPZ)2Cl2] (Cu-Complex), where IPZ = 4-Iodopyrazole) by pyrolysis method and exploiting the stability and modulation of the coordination sites of sorbitol/mannitol, which exhibited excellent photocatalytic properties. The results showed that Cu/CuxO@C possessed high efficiency in degrading rhodamine B (RhB), gentian violet (GV), methyl orange (MO) and Congo red (CR) dyes under UV irradiation, and the degradation effect was gradually enhanced with the increase of calcination temperature. The structural and chemical states of the materials were characterised in detail. Furthermore, the effects of experimental factors such as catalyst dose, solution pH, and inorganic anions on dye degradation efficiency were investigated. The photocatalytic mechanism study demonstrated that the primary oxygen-active substance was superoxide radical (·O2-). The electron transport hypothesis explains the effective separation of electrons and holes within a substance. The Cu/CuxO@C composite was regarded as a potential photocatalyst for dye wastewater treatment due to its high photocatalytic efficiency, reusability, and universality, offering a novel solution to environmental and energy issues.

Feasibility of upcycling red mud for low-CO2 cement via calcination: A comparative study with FA and GGBFS based in China

This study examines the feasibility of developing low-CO2 cement using calcined red mud (RM) and explores positive scenarios that simultaneously attain technical, environmental, and economic benefits in reference to conventional fly ash (FA) and ground granulated blast furnace slag (GGBFS) cements. Based on the variables of RM's content and calcination temperature, we investigated the fresh properties (paste rheology and mortar flowability), strength development, microstructure, embodied CO2 emissions, and cost of the RM-blended cement. The results show that there was an optimal range of RM's calcination temperature (400–600 °C) that improved the cement paste viscosity while attaining a higher strength than that of FA cement. Considering the cradle-to-gate CO2 emissions and cost of cement production, the optimal cement composition is comprised of up to 30% RM calcined at 600 °C, where the cement cost is lowered by 19.3% compared to the FA reference having a comparable CO2 footprint. According to the geographical analysis, the calcined RM shows minimal advantages over GGBFS but could substitute FA as a cleaner, cheaper, and more reactive supplementary cementitious material in regions where electricity grid is dominated by clean energy. Therefore, RM offers a plausible solution to future low-CO2 cement in light of the increasing shortage of FA led by the declining use of coal-powered electricity.

Design, preparation, and performance of marine resource-based alkali-activated cementitious materials

The construction of islands and reefs and marine engineering cannot depend on cementitious materials, and how to utilize marine resources to prepare cementitious materials is the key to realizing the convenient construction of marine engineering. In this paper, starting from the necessary composition for the formation of gels, the effects of different activation methods on their activities were investigated by utilizing coral and diatomite as calcium and silicon sources, respectively. The study results show that using calcined coral to activate calcined diatomite resulted in a 28 days strength of up to 2.89 MPa, but it was not processable. The precursor with volcanic ash can be prepared by co-calcining coral and diatomite under lower temperature conditions, and its calcination temperature needs to be no less than 800 °C. In addition, characterization by XRD, FTIR, SEM and BET showed that increasing the calcination temperature helps to form more active substances with volcanic ash, such as CaO, CaSiO3, and Ca2SiO4, which can improve the compressive strength of alkali-activated materials prepared from them. The highest strength growth rate of 3.03 % and 28 days compressive strength of 10.80 MPa were obtained when the co-calcined temperature was 850 °C. The results of this study can provide some reference for the development of marine resource-based cementitious materials.

EXTRACTION OF PURE ALUMINA FROM KAOLIN: A REVIEW

This study demonstrated that high-purity alumina can be generated from kaolin using various methods. It examined different leaching techniques, considering the size and percentage recovery of alumina by weight in selected kaolin samples, the calcination temperature, and the molar concentration of acids over time. Additionally, it analyzed the characteristics of several kaolin sources in Nigeria with the aim of extracting alumina. The research indicates that Nigerian kaolinite clay typically contains 22–40% alumina by weight. However, leaching kaolin yielded alumina with a purity of 60–97 wt%, with particle sizes ranging from 16 to 177 nm. Alumina derived from kaolin is deemed beneficial for manufacturing refractory materials, water purification, and biomedical applications.

Biodiesel Synthesis from Date Seed Oil Using Camel Dung as a Novel Green Catalyst: An Experimental Investigation

Biodiesel is seen as more environmentally benign than petroleum-based fuels. It is also cheaper and capable of creating cleaner energy, which has a good impact on increasing the bioeconomy. An investigation was conducted on a novel heterogeneous catalyst system utilized in the synthesis of eco-friendly biodiesel from date seed oil, a non-edible feedstock obtained through the calcination of desiccated camel manure at varying temperatures. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, and scanning electron microscopy (SEM) were utilized to characterize this catalyst. As a result of raising the calcination temperature, the results showed that the pore size of the catalyst decreased. The biodiesel production was optimized to be 86% by using the transesterification method. The optimal reaction parameters included a catalyst with 4% loading, a molar ratio of 1:8 between date seed oil and ethanol, and a temperature of 75 °C for a reaction period of three hours. The confirmation of FAME generation was achieved by gas chromatography–mass spectrometry (GC–MS). The fuel qualities of fatty acid ethyl ester are in accordance with ASTM, suggesting that it is a suitable alternative fuel option. Utilizing biodiesel derived from waste and untamed resources to establish and execute a more sustainable and ecologically conscious energy plan is praiseworthy. The adoption and integration of green energy practices could potentially yield positive environmental outcomes, thereby fostering enhanced societal and economic development for the biodiesel sector on a broader scale.

Optimizing Construction Spoil Reactivity for Cementitious Applications: Effects of Thermal Treatment and Alkaline Activation

Construction spoil (CS), a prevalent type of construction and demolition waste, is characterized by high production volumes and substantial stockpiles. It contaminates water, soil, and air, and it can also trigger natural disasters such as landslides and debris flows. With the advent of alkali activation technology, utilizing CS as a precursor for alkali-activated materials (AAMs) or supplementary cementitious materials (SCMs) presents a novel approach for managing this waste. Currently, the low reactivity of CS remains a significant constraint to its high-value-added resource utilization in the field of construction materials. Researchers have attempted various methods to enhance its reactivity, including grinding, calcination, and the addition of fluxing agents. However, there is no consensus on the optimal calcination temperature and alkali concentration, which significantly limits the large-scale application of CS. This study investigates the effects of the calcination temperature and alkali concentration on the mechanical properties of CS–cement mortar specimens and the ion dissolution performance of CS in alkali solutions. Mortar strength tests and ICP ion dissolution tests are conducted to quantitatively assess the reactivity of CS. The results indicate that, compared to uncalcined CS, the ion dissolution performance of calcined CS is significantly enhanced. The dissolution amounts of active aluminum, silicon, and calcium are increased by up to 420.06%, 195.81%, and 256.00%, respectively. The optimal calcination temperature for CS is determined to be 750 °C, and the most suitable alkali concentration is found to be 6 M. Furthermore, since the Al O bond is weaker and more easily broken than the Si O bond, the dissolution amount and release rate of active aluminum components in calcined CS are substantially higher than those of active silicon components. This finding indicates significant limitations in using CS solely as a precursor, emphasizing that an adequate supply of silicon and calcium sources is essential when preparing CS-dominated AAMs.

MoC nanoparticles decorated carbon nanofibers loaded with Li2S as high-performance lithium sulfur battery cathodes

Lithium sulfur (Li-S) batteries have broad development potential in the field of electrochemical energy storage due to their high theoretical specific capacity, low cost, and environmentally friendly. However, the notorious shuttle effect of lithium polysulfides (LiPSs) during cycling process severely limits the performance improvement of Li-S batteries. In this work, carbon nanofibers (CNFs) decorated by MoC nanoparticles have been successfully established through electrospin combined with carbothermal reduction method. The effect of calcination temperature and MoC loading amount on the catalytic activity on LiPSs, as well as the electrochemical performance have been first investigated in detail. Based on the visualized adsorption and LiPSs conversion kinetics testing, the CNFs@MoC composites with 37 wt% MoC loading (CNFs@MoC-37 %) are confirmed to be the optimized sample. By using liquid-phase impregnation to load Li2S onto the CNFs@MoC-37 % composites to act as cathode, the assembled cells can achieve a reversible capacity of 941 mAh g−1 and 751 mAh g−1 at the current density of 0.1C and 1C respectively. The reversible capacity can still maintain at 550 mAh g−1 at 1C after 500 cycles, corresponding to the capacity decay rate of 0.054 % per cycle.

Magnetically recyclable PrFeO3/g-C3N4 nano-photocatalyst with Z-scheme structure: Synthesis and characterization and its application for enhanced degradation of malachite green as contaminated water under sunlight

Using the modified sol–gel process, PrFeO3 nanoparticles were produced with citric acid, maleic acid and malic acid present as carboxylic acids. Research has been done on the effects of calcination temperature, and fuel type as operational synthesis factors on the product’s characteristics. The nanocomposites based on PrFeO3 was fabricated with different percentage of g-C3N4. The resultant flawless sample was used as a photocatalyst to degrade organic dyes under visible light due to narrow band gap (2.42 eV). The scavengers for active agents were examined in order to better understand the process of photocatalytic degradation. Thus, maximal efficiency (93 %) was obtained employing 0.06 g PrFeO3/g-C3N410% nano-photocatalysts in 5 ppm malachite green. The optimized sample shows proper structural stability and recycles ability after 5 runs.

Simplified synthesis and identification of novel nanostructures consisting of cobalt borate and cobalt oxide for crystal violet dye removal from aquatic environments

Crystal violet dye poses significant health risks to humans, including carcinogenic and mutagenic effects, as well as environmental hazards due to its persistence and toxicity in aquatic ecosystems. This study focuses on the efficient removal of crystal violet dye from aqueous media using novel Co3O4/Co3(BO3)2 nanostructures synthesized via the Pechini sol–gel approach. The nanostructures, which were abbreviated to EN600 and EN800, were fabricated at calcination temperatures of 600 and 800 °C, respectively. X-ray diffraction (XRD) analysis revealed that the synthesized samples have a cubic Co3O4 phase and an orthorhombic Co3(BO3)2 phase, with mean crystal sizes of 43.82 nm and 52.93 nm for EN600 and EN800 samples, respectively. The Brunauer–Emmett–Teller (BET) surface areas of EN600 and EN800 samples were 65.80 and 43.76 m2/g, respectively, indicating a significant surface area available for adsorption. Optimal removal of crystal violet dye was achieved at a temperature of 298 K, a contact time of 70 min, and a pH of 10. The maximum adsorption capacities were found to be 284.09 mg/g for EN600 and 256.41 mg/g for EN800, which are notably higher compared to many conventional adsorbents. The adsorption process followed the pseudo-second-order kinetic model and fitted well with the Langmuir isotherm. The adsorption was exothermic, spontaneous, and physical in nature. Moreover, the adsorbents exhibited excellent reusability, retaining high efficiency after multiple regeneration cycles using 6 mol/L hydrochloric acid. These findings highlight the potential of these Co3O4/Co3(BO3)2 nanostructures as effective and sustainable materials for water purification applications.

Size‐Dependent Catalytic Activity Over MOF‐Derived Cobalt Oxide Supported PdO Nanoparticles in Suzuki Reaction

ABSTRACTPalladium nanoparticles immobilized on ZIF 67‐derived porous CoOx were prepared by wet‐impregnation method, followed by calcination at different temperatures. The calcination temperature has been employed to effectively manipulate the size of metal nanoparticles, where higher calcination temperatures resulted in larger sizes. The experimental results revealed that by manipulating the calcination temperature, the synthesis of palladium nanoparticles with varying sizes could be effectively controlled. Increasing the calcination temperature resulted in larger particle sizes. At a calcination temperature of 350°C, the synthesis process produced the smallest palladium nanoparticles, averaging 1.35 nm in size, facilitating the reaction between aryl halides and arylboronic acids with yields ranging from 83% to 99%. Furthermore, these nanoparticles demonstrated superior catalytic activity and recyclability.

Carbon-doped CuO nanoparticle-constructed single tube adsorbent for high efficient adsorption of Pb2+ at near room temperature

How to prepare adsorbents using economical, environmentally friendly and simple methods has become the focus of research. In this paper, silk cotton (SC) was used as a biomass template impregnated with copper nitrate solution and then calcined to prepare CuO-based adsorbent. Carbon-doped CuO (C/CuO-400) adsorbent was obtained under 400 °C air calcination calcination. It completely replicates the morphology of kapok and consists of uniformly smaller nanoparticles. The effects of different calcination temperatures, adsorption temperatures, adsorption times, adsorbent dosages and different concentrations on the adsorption of lead ions were investigated. The results showed that C/CuO-400 had a good adsorption effect on Pb2+, which was suitable for Pseudo second-order and Langmuir, and the maximum adsorption amount of Pb2+ was 588.24 mg/g with good Reusability. This environmentally friendly, economical and simple to operate biomass template prepared adsorbent of single tube C/CuO has good adsorption effect on lead ions, which is very meaningful and easy to promote the preparation of adsorbent.

Impact of calcined temperatures on the crystalline parameters, morphological, energy band gap, electrochemical, antimicrobial, antioxidant, and hemolysis behavior of nanocrystalline tin oxide

To construct a battery, the precipitation-synthesized SnO2 products at 450 °C and 650 °C were separately taken and mixed with graphite as the anode and PbO2,V2O5, and graphite materials as cathode materials to make the pellets and examine their open circuit voltage (OCV) values. The microstrain, lattice parameter, and crystallite size values of the above-mentioned tin oxide compounds were obtained through Rietveld refinement-MAUD fit analysis. The microstrain and lattice parameter values of tin oxide were significantly varied at a higher calcined temperature. Surface particle grain growth was increased with the increased calcined temperature from 450 to 650 °C as evidenced by FE-SEM study. Particle size distributions of SnO2 and polycrystalline behavior have been discussed with the aid of TEM analysis. From the UV–visible spectra, optical band gap (Eg) values reduced from 3.73 to 3.69 eV for the SnO2 products with an increase in calcined temperatures from 450 to 650 °C. The antimicrobial responses of the two different calcined SnO2 samples at 450 °C and 650 °C against two different bacterial pathogens (gram-positive-S. aureus and gram-negative-E.coli) were investigated. From the microbicidal assessment, a relatively higher diameter of the zone of inhibition (DZOI) of tin oxide at 650 °C samples was measured to be 19 ± 2 mm and 21 ± 2 mm for S. aureus and E. Coli than the DZOI of SnO2 at 450 °C samples (15 ± 1 mm for S. aureus and 18 ± 1 mm for E. coli. DPPH scavenging activity at 100 μg/ml shows that SnO₂ calcined at 450 °C achieves 68 ± 1 %, while SnO2 calcined at 650 °C exhibits a significantly higher activity of 86 ± 1 %. A slight increase in hemolysis was observed for SnO2 calcined at 650 °C, reaching 1.3 % at higher concentrations, but overall, hemolysis remained below 5 %, indicating high hemocompatibility.

Coconut Shell Carbon Preparation for Rhodamine B Adsorption and Mechanism Study.

Phosphoric acid is used as a chemical activator to prepare coconut shell carbon (PCSC), and for investigating rhodamine B (RhB) adsorption performance. The optimal conditions for the preparation of PCSC (calcined temperature, phosphoric acid concentration), and the influence of adsorption conditions (concentration, pH, etc.) on RhB and the recovery performance of optimal carbon are investigated. Experimental results show that when the amount of PCSC (600 °C, 2 h) is 0.2 g, the initial RhB concentration is 10 mg/L, pH = 6, and the adsorption time is 30 min, it can have 95.84% RhB adsorption efficiency. Liquid ultraviolet spectroscopy also supports this adsorption performance. Characterization data showed that hydroxyl and ester groups, aromatic structures, and PO43- existed on the surface of PCSC, and the amount decreased with increasing calcined temperature. PCSC has a BET (N2) surface area of 408.59 m2/g and has a micropore distribution, EDS-detected P content is 3.91%. SEM showed that the PCSC formed micropores which could better adsorb RhB. The kinetic and thermodynamic analysis of the adsorption of RhB by PCSC showed that the adsorption process was in accord with quasi-secondary kinetic equations and ΔGθ was between -1.65 and -18.75 kJ/mol. The adsorption was a physical adsorption and a spontaneous endothermic reaction, and the obtained PCSC sorption isotherms were classified as Langmuir-type. The RhB adsorption mechanism on PCSC includes pore diffusion, hydrogen bonding, and π-π conjugation. The PCSC prepared by H3PO4 modification has superior adsorption and recycling performance for RhB, providing a reference for the preparation of other biomass carbon materials for the treatment of dye wastewater.

Surface Engineering of N‐Doped Carbon Derived from Polyaniline for Primary Zinc‐Air Batteries

AbstractZinc‐air batteries (ZABs) with metal‐free cathodes are considered environmentally friendly and cost‐effective. However, more active and durable catalysts are required for this purpose. Herein, polyaniline (PANI)‐derived carbon materials were obtained to boost the oxygen reduction reaction (ORR) and, consequently, the performance of a primary ZAB. The developed porous N‐doped carbon (NDC) materials were engineered by varying the polymerization time and calcination temperature (500–900 °C). SEM micrographs and BET surface areas showed that the polymerization of aniline under cold conditions (5 °C) at 6, 8, or 24 h did not have a significant effect on the morphology or surface area. The fibrous structure of PANI was engineered by temperature, resulting in a progressive increase in the surface area until a three‐dimensional porous structure was achieved at 900 °C with the highest area of 601.9 m2 g−1. The surface doping of nitrogen species shifted from PANI‐rich N species to enriched graphitic N from 12.69 % (500 °C) to 24.26 % at 900 °C. The NDC 900 °C presented a voltage of 1.4 V and power density of 56 mW cm−2 (only 7 mW cm−2 lower than that of Pt/C). The results demonstrate that this material is an excellent candidate for high‐performance primary ZABs.

Effect of Calcination Temperature on the Surface of Prepared ZnO Nanocatalysts

ZnO nanoparticles (NPs) having nsemiconducting properties are important nanocatalysts for many surface reactions. Because of their extensive use as heterogeneous nanocatalyst for energy production and environmental cleaning, it is essential to understand their surface properties to design better chemical and photochemical nanocatalysts. Here, we used the sol-gel method to develop numerous ZnO NPs at various calcination temperatures (300 - 800 oC) and analyzed by different surface characterization techniques such as FTIR, SEM, XRD and UV-visible absorption spectroscopy. To investigate the catalytic activity a series of photooxidation studies on Remazol Red RR (RRR) were carried out at different conditions. From the surface characteristic analysis, it is found that the crystalline ZnO NPs are formed at above 400 oC temperature. The highest photocatalytic efficiency is found at 500 oC which might be related to the lowest particle size (35.4 ± 5.2 nm) and surface heterogeneity. The experimental results suggest that temperature-controlled growth rate and intra/inter-particle heterogeneity of ZnO nanoparticles have a great impact on the surface properties and photocatalytic activity. In addition to surface area, surface defects and crystal deformation may have a considerable impact on the photocatalytic activity by ZnO NPs. Finally, this study will help to understand what type of surface properties need to optimize to design industrial suit ZnO nanocatalysts. Journal of Engineering Science 15(1), 2024, 75-81