Ceria-zirconia based mixed oxides (CZs) have been applied in three-way catalysts (TWCs) for their high surface area and oxygen storage capacity (OSC). In this work, enhanced thermal stability of ...Ce0.33Zr0.55(LaNdY)0.12O2 mixed oxides was realized via a facile and scalable approach, namely, sulfate-aided coprecipitation method was labelled as CZ-S. Sulfate ion (SO42−) was added into raw solution in the form of sulfuric acid and acted as coordination agent. The control sample was prepared by conventional coprecipitation method without sulfuric acid added and labelled as CZ. The promotion effect of sulfate ion was analyzed systematically by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), OSC and hydrogen temperature-programmed reduction (H2-TPR) analysis. XRD and high resolution TEM results reveal that CZ-S have homogeneous distributions of elements. TEM and SEM images show that fresh samples of CZ-S have narrower distributions of grain sizes and larger pore sizes than those of CZ. Through cross analysis of structure and morphology of CZ and CZ-S, we find that the introduction of sulfate ions results in uniform distributions of elements, narrows distributions of grain sizes, and enables the formation of secondary loose packing of sub-particles, which lead to enhanced thermal stability of the samples of CZ-S upon aging process at high temperature. After aging treatment at 1100 °C for 10 h, aged samples of CZ-S present larger specific surface areas and pore volumes than the aged sample prepared by conventional coprecipitation method without sulfate ions added. Furthermore, the aged sample of CZ-S2 (SO42−/Zr = 1) possesses the highest specific surface area of 21.9 m2/g and the biggest pore volume of 0.035 mL/g among all aged samples.
The introduction of sulfate ions during precipitation results in uniform distributions of elements, narrows distributions of grain sizes, and enables the formation of secondary loose packing of sub-particles, which lead to enhanced thermal stability of the samples of CZ-S upon aging process at high temperature. Display omitted
•Enhanced thermal stability of Ce0.33Zr0.55(LaNdY)0.12O2 mixed oxides was realized via sulfate-aided coprecipitation method.•The use of sulfate ions results in uniform distributions of elements and a secondary loose packing of sub-particles for CZs.•CZ-S2 possesses the highest specific surface area of 21.9 m2/g after ageing treatment at 1100 °C for 10 h among all samples.
•Acid etching and NH3 activation exposed more homodispersed Fe-Nx-C active sites.•Fe-PCNRs-700 has a hierarchical porous structure and huge specific surface area.•Fe-PCNRs-700 exhibits excellent ORR ...activity in acidic and alkaline media.•Zn-air batteries are assembled with high power density and robust stability.
Acid etching and NH3 activation can not only increase the specific surface area of the catalyst, but also expose more Fe–Nx–C active sites. Finally, the prepared Fe-PCNRs-700 exhibited excellent ORR activity and Zn-air battery performance. Display omitted
Decorating porous carbon nanomaterials with rich homodispersed metal cluster and heteroatoms can effectively shorten the diffusion pathway of oxygen and expose more active sites, thereby promoting oxygen reduction reaction (ORR). Herein, hierarchical porous carbon nanorods with homodispersed Fe–Nx–C active sites are obtained by calcination, etching and ammonia activation of Fe-nitrogenous acid (NTA) coordination polymer nanowires. The obtained Fe-PCNRs-700 as ORR catalysts show the excellent activity with half wave potential (E1/2) of 0.71 V vs. reversible hydrogen electrode (RHE) in 0.5 M H2SO4 and 0.87 V vs. RHE in 0.1 M KOH electrolyte, which owe to its huge specific surface area (1652 m2 g−1), hierarchical pore structure, homodispersed Fe–Nx–C active sites and structural defects. Furthermore, using Fe-PCNRs-700 as a cathode catalyst in both liquid and flexible solid Zn-air batteries, and the assembled liquid batteries display the high power density of 161 mW cm−2 and robust charge/discharge stability of 116 h.
•Experimental and numerical study of turbulent heat transfer of GNP nanofluid.•The convective heat transfer coefficient of the GNP nanofluid enhanced up to 200%.•The pressure drop increased about ...0.06 to 14.7% compared to the base fluid.
The convective heat transfer coefficient and friction factor for fully developed turbulent flow of graphene nanoplatelet (GNP) nanofluids of varying specific surface areas flowing through a horizontal stainless steel tube with a uniform heat flux are experimentally determined. The thermo-physical properties of the GNP nanofluid, including the thermal conductivity and viscosity, are measured at various temperatures, specific surface areas (300, 500, and 750m2/g) and concentrations (0.025, 0.05, 0.075, and 0.1wt%). To validate the reliability and reproducibility of the experimental setup for calculating the convective heat transfer coefficient and for providing a baseline to compare the GNP nanofluid data, several tests are conducted for distilled water. The main objective is to evaluate the effect of specific surface area of GNP nanoparticles for varying concentrations on heat transfer under turbulent flow conditions. The convective heat transfer coefficient of the GNP nanofluid is found to be higher than the base fluid by approximately 83–200%. Further, the heat transfer coefficient of the GNP nanofluid increases as the flow rate and the specific surface area increase. However, the pressure drop increases simultaneously in the range 0.06–14.7%. The results suggest that GNP nanofluids could function well as working fluids in heat transfer applications and provide good alternatives to conventional working fluids.
The review of modern scientific and technical literature on supercapacitors produced by industrial companies is presented. The advantages of supercapacitors compared to batteries are: high power ...density, high cycleability, the ability to operate at extreme temperatures from –50 to +60°C, energy efficiency up to 100% and the ability to charge in a very short time. The review examines the characteristics of supercapacitors manufactured by the following companies: Maxwell Technologies (California, USA), NessCap (Republic of Korea), ApowerCap (California, USA), Skeleton Technologies (Germany, Estonia), EPCOS (Munich, Germany), Panasonic (Osaka, Japan), Fuji Heavy (Shibuya, Japan), Asahi Glass (Tokyo, Japan), ESMA (Moscow region, Russian Federation). The characteristics considered in the article include specific energy, power density, full discharge time, full charge time, discharge efficiency, the number of full cycles, rated voltage and temperature range.
The physicochemical properties of oyster shell-derived adsorbents prepared by calcination at different temperatures were characterized by elemental analysis, specific surface area, particle size ...distribution, X-ray diffraction, and scanning electron microscopy. The pH value in natural oyster shell increased from 9 to 12.7 following calcination above 750 °C. All of the oyster shell-derived adsorbents exhibited a BET surface area that ranged from 1.8 to 64.6 m2/g. Clearly, the proportion of particles within the ranges 25–50 μm and 50–100 μm increased after calcination, regardless of calcination temperature.
The adsorption equilibrium and kinetics of cadmium (Cd) were investigated, and the mechanisms of sorption discussed. Experimental equilibrium data were fitted to a Langmuir adsorption isotherm model. Most Cd adsorption occurred during the initial hours of contact time, and a pseudo-second-order kinetic model best fitted the adsorption process. Cd sorption profiles indicated an initial, low Cd sorption region (25.25–32.36 mg/g) that was associated with calcination temperatures of up to 650 °C for 2 h, and a second region that contributed to high Cd sorption from 750 °C, with the maximum sorption capacity reaching a value of 1666.67 mg/g at 900 °C. The high Cd-removal capacity of oyster shell-derived adsorbents above 750 °C is attributed to their enhanced specific surface area, their material porosity, the bulk precipitation of Cd hydroxide and otavite on shell fragments, the formation of ettringite as a secondary precipitate, and ion exchange via Ca ions. This study highlights the effectiveness of calcined oyster shells in Cd removal from highly contaminated water and wastewater.
•An effective biosorbent was fabricated by thermally treating oyster shells.•Calcination enhanced specific surface area and created a porous surface morphology.•Calcined oyster shells at >750 °C increased Cd2+ removal from aqueous solutions.•Bulk precipitation of Cd(OH)2 and otavite was the main Cd2+ uptake mechanism.•Cd exchange with Ca2+ and incorporation of Cd2+ into ettringite also occurred.
BEaTmap is an open-source software designed to improve the analysis of isothermal adsorption data. The specific surface area of a porous material is commonly obtained through applying the classic BET ...theory to the adsorption of inert gases and vapors in the relative pressure range of 5% to 35% and presented as a single value. However, this cookie-cutter approach can yield thermodynamically inconsistent results that are incorrect or misleading. BEaTmap provides a conceptual tool for analyzing the entire set of isothermal adsorption data with BET theory and presents the range of all possible values that are thermodynamically and mathematically consistent. The analysis is presented as a heatmap indicating the results for all valid relative pressure ranges, offering the user a more comprehensive specific surface area answer. The code is written in Python and is available as both a web app and Python package. BEaTmap, documentation, and examples are freely available on GitHub. Keywords: BET, specific surface area, Python, adsorption, isotherm
Al/CuO nanoenergetic materials with nanotube and nanorod morphologies were prepared and investigated in this study. The CuO nanotubes and nanorods synthesized by chemical etching are homogenous on a ...large scale, with an external diameter in the range of 100–200nm and typical lengths of 5–7μm. Each of these CuO nano-arrays was deposited on nano-Al by electrophoretic deposition. Using the Brunauer-Emmett-Teller method, the Al/CuO nanotube composite is determined to have a larger specific surface area (43.20m2/g) than that of the Al/CuO nanorod composite (16.75m2/g). The energy released from the Al/CuO nanotubes is approximately to 3264J/g, which is higher than that released from the Al/CuO nanorods (2013J/g). The combustion flames for the Al/CuO nanotubes are also more rapid and violent. It is speculated that the excellent output of energy and outstanding combustion performance of the Al/CuO nanotubes could be ascribed to their tubular architecture, which has a larger specific surface area enhances the intimate contact and mass transmission between fuel and oxide.
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•The CuO nanotubes and nanorods were synthesized successfully by chemical etching without using a template.•The energy release and combustion performance of the Al/CuO nanotubes are enhanced due to its tubular architecture.
The vital issues of rechargeable lithium batteries widely used for everyday energy storage is being studied by many researchers to enhance the battery performance and safety. Graphene as well as ...cheaper and more accessible reduced graphene oxide (rGO) are known for high electrical conductivity, specific surface area and chemical stability. Providing thus high specific power and long cycle life, graphene and rGO in the form of porous frameworks like aerogels, foams, sponges (all denoted here as GA) have been successfully tested in electrodes of various types of lithium batteries. In this article, we review advances in synthesis and use of GA in high-performance electrode materials of lithium-ion (Li-ion), lithium-sulfur (LiS), and lithium-air (LiO2) batteries. Published results on the specific capacity of the lithium-battery electrodes using GA, the effect of GA on the cycling stability, and methods to enhance the performance of Li-ion, LiS and LiO2 batteries using porous microstructure of GA are overviewed and discussed. Thus, we provide an in-depth summary on diverse promising approaches of significant breakthroughs in recent years and present strategies to choose porous graphene frameworks for the sustainable lithium-battery electrodes.
•Graphene aerogel (GA) is overviewed as a material for lithium battery electrodes.•GA in anodes and/or cathodes enhances the performance of Li-ion batteries.•GA is successfully used in cathodes of LiS and Li-air batteries.•GA electrode pore size plays more decisive role than its specific surface area.•More detailed research reports facilitate the electrode performance comparison.
The hydration of C3A-gypsum systems was studied in the presence of various types of sulfates such as gypsum, hemihydrate and Na2SO4 in the first hour. The BET method combined with a DSC analysis ...enabled us to quantitatively characterize the amount of precipitated ettringite and its specific surface area along the hydration. It was found that sulfates not only affected the formation rate of ettringite, but also had a significant impact on the morphology of ettringite. For all the C3A-gypsum systems, a large part of the ettringite precipitated within the first 20 min and the specific surface area of the hydrated sample strongly increased within the first 5 min, whereas the specific surface area of ettringite gradually decreased along the C3A hydration reaction. Incorporating a small amount of Na2SO4 in the C3A-gypsum system could greatly promote the formation rate of ettringite in the first 20 min, and significantly decrease the specific surface area of ettringite. As hemihydrate was added to the C3A-gypsum system, two processes of ettringite precipitation and gypsum precipitation occurred. The nucleation and growth process of ettringite and gypsum resulted in the complex changes in the specific surface area of the hydrated sample, which first increased at the very beginning, then decreased and, finally, increased.
In this paper, the LaAlO
3
perovskite with large specific surface area and abundant surface oxygen vacancies is prepared by the hard template method, on which Ni metal nanoparticles and CaO alkaline ...additives are loaded. The generated catalyst is applied to the study of methane dry reforming. By analyzing and characterizing all catalysts prepared through BET, XRD, TEM, XPS, H
2
-TPR and other test methods, the LaAlO
3
Hperovskite prepared by the hard template method can obtain both larger specific surface area and more abundant surface oxygen vacancies than the LaAlO
3
-C perovskite prepared by the traditional sol–gel method. As a result, the Ni-based catalysts supported by LaAlO
3
-H perovskite exhibit more favorable anti-sintering and anti-carbon deposition ability than Ni/LaAlO
3
-C catalyst. (Adding) CaO can enhance the adsorption of CO
2
on Ni-based catalysts, so N-CaO/LaAlO
3
catalyst possesses the most excellent anti-carbon deposition ability.
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