Narrow Pore Size Distribution Research Articles

Facile Synthesis of Polymer-Reinforced Silica Aerogel Microspheres as Robust, Hydrophobic and Recyclable Sorbents for Oil Removal from Water.

With the rapid development of industry and the acceleration of urbanization, oil pollution has caused serious damage to water, and its treatment has always been a research hotspot. Compared with traditional adsorption materials, aerogel has the advantages of light weight, large adsorption capacity and high selective adsorption, features that render it ideal as a high-performance sorbent for water treatment. The objective of this research was to develop novel hydrophobic polymer-reinforced silica aerogel microspheres (RSAMs) with water glass as the precursor, aminopropyltriethoxysilane as the modifier, and styrene as the crosslinker for oil removal from water. The effects of drying method and polymerization time on the structure and oil adsorption capacity were investigated. The drying method influenced the microstructure and pore structure in a noteworthy manner, and it also significantly depended on the polymerization time. More crosslinking time led to more volume shrinkage, thus resulting in a larger apparent density, lower pore volume, narrower pore size distribution and more compact network. Notably, the hydrophobicity increased with the increase in crosslinking time. After polymerization for 24 h, the RSAMs possessed the highest water contact angle of 126°. Owing to their excellent hydrophobicity, the RSAMs via supercritical CO2 drying exhibited significant oil and organic liquid adsorption capabilities ranging from 6.3 to 18.6 g/g, higher than their state-of-the-art counterparts. Moreover, their robust mechanical properties ensured excellent reusability and recyclability, allowing for multiple adsorption-desorption cycles without significant degradation in performance. The novel sorbent preparation method is facile and inspiring, and the resulting RSAMs are exceptional in capacity, efficiency, stability and regenerability.

Vancomycin-loaded porous chitosan-pectin-hydroxyapatite nanocomposite coating on Ti6Al4V towards enhancing prosthesis antiinfection performance

Cathodic electrophoretic deposition (EPD) was used to fabricate novel porous chitosan/pectin/hydroxyapatite (CS/P/HA) nanocomposite coatings on Ti6Al4V substrates. Rietveld refinement results revealed variations in peak intensity, position, and width, reflecting structural changes resulting from the reduction of the applied voltage from 30 to 10 V. The deposits obtained at 10 V after 1 h of presedimentation exhibited a denser microstructure with narrow pore size distribution compared to the others. The wettability and adhesion strength of coated Ti6Al4V improved with increasing HA content. Release of antibiotic from the composite coating confirmed 40% initial burst release, 50% semi-steady release and 10% residual release. A thick and uniform porous apatite layer was formed on Ti6Al4V after 21 days of immersion in simulated body fluid (SBF). Therefore, CS/P/HA coated Ti6Al4V has the potential for practical antiinfection performance.

Comparative Surface Study of Ru/Cu- and Ag/Cu-Doped RHS Catalysts from Waste Biomass for Biofuel Application.

The present study compares the surface, textural, and catalytic properties of porous silica doped with bimetallic metal ions that was made from rice husk (RH) biomass. Due to the use of a surfactant during the synthesis process, porous RH-silica (RHS) was derived. In situ doping of silver/copper and ruthenium/copper has been achieved via the xerogel and hydrogel formation methods. The prepared catalysts have been analyzed by various methods, such as surface area and narrow pore size distribution, to confirm their porosity. Powder X-ray diffraction, Fourier transform infrared, and electron microscopy examination were further performed for physicochemical characterization of the synthesized materials. Transmission electron microscopy images showed that ruthenium and copper ions were incorporated perfectly, forming a hexagonal mesoporous (MCM-41) texture due to hydrogel formation and the method of preparation. Copper oxide nanoparticles with silver incorporation in RHS form cube-shaped particles for CuO formation on the surface of the silica matrix instead due to the method of preparation. In this case, ruthenium/copper-doped porous silica forms hexagon-shaped particles of RuO formation in the mesoporous matrix. Finally, the acetylation of glycerol using acetic acid on as-prepared catalysts has been studied. The catalytic activity increases with an increase in temperature and optimization of the molar ratio of glycerol and acetic acid. Increases in temperature result in higher selectivity toward triacetin formation instead of the conventional formation of monoacetin. Hence, we compared the surface physicochemical properties, catalytic conversion, and selectivity nature of bimetallic metal (Ru/Cu and Ag/Cu) ions incorporated in RHS prepared by different synthetic routes.

One-Pot Mechanochemical Synthesis of Carbons with High Microporosity and Ordered Mesopores for CO2 Uptake at Ambient Conditions.

Mechanochemical synthesis of ordered mesoporous carbons with tunable mesopores and well-developed irregular microporosity is investigated. This synthesis was carried out by the self-assembly of ecofriendly chemicals such as tannin and glyoxal used as carbon precursors, and triblock copolymer as a soft templating agent. The structural properties of the resulting carbons were tailored by using different block copolymers (Pluronic F127, and P123) as soft templates. The various weight ratios of tannin and block copolymer were employed to tune the textural properties of these carbons. The tannin: Pluronic F127 ratios (1:0.75, 1:1, 1:1.1) gave the ordered mesoporous carbons among a wide variety of the samples studied. The ordered mesoporosity was not observed in the case of Pluronic P123 templated mesoporous carbons. The CO2-activated carbon samples obtained for both Pluronic templates showed a high specific surface area (close to 900 m2/g), large pore volume (about 0.6-0.7 cm3g-1), narrow pore size distribution, and high CO2 uptake of about 3.0 mmol g-1 at 1 bar pressure and ambient temperature.

Preparation of Mesoporous γ-Alumina from Red Mud Waste

In this paper, a novel green and cost-effective synthesis method in this field is presented. Mesoporous γ-alumina was obtained by inorganic in situ crystallization, and sodium aluminate as an aluminum origin was abstracted from red mud. The influence mechanism of the reactant ratio of NaHCO3 to NaAlO2, the reaction temperature and the concentration of the template was systematically investigated. As indicated by the results, the obtained mesoporous γ-alumina possesses extensive specific surface areas, narrow pore size distribution, nearly spherical particle morphology and wormlike structure pores. This green and economical synthesis method can be used for the preparation of alternative mesoporous or various porous materials as well.

Copper Immobilized over 2D Hexagonal SBA-15 for Electrochemical and Colorimetric Sulfite Sensing.

Sulfite (SO32-) is considered a highly toxic anion for living organisms. Herein, we report the synthesis of copper immobilized over a 2D hexagonally ordered mesoporous silica material CuMS as an electrochemical and colorimetric dual-technique-based sensing platform for sulfite detection. The immobilization of copper on silica was achieved through the bis[3-(triethoxysilyl)propyl]tetrasulfide (TEPTS) ligand. Morphological and physical properties of the material were confirmed by several characterization techniques, including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 sorption, and X-ray photoelectron spectroscopy. The CuMS material retained mesoporosity with a narrow pore size distribution (D ≈ 5.4 nm) and a high Brunauer-Emmett-Teller surface area of 682 m2 g-1 after the immobilization of copper. The prepared catalyst shows promising electrocatalytic activity toward sulfite oxidation. A linear variation in the peak current was obtained for SO32- oxidation in the 0.2-15 mM range with a high sensitivity of 62.08 μA cm-2, under optimum experimental conditions. The limit of detection (LOD) was found to be 1.14 nM. CuMS also shows excellent activity toward colorimetric detection of sulfite anions with an LOD of 0.4 nM. The proposed sensor shows high selectivity toward the sulfite anion, even in the presence of common interferents. The detection of sulfite in white wine with excellent recovery demonstrates the practical applicability of this sensor.

Experiment on and modeling of purification of fructooligosaccharides using ceramic nanofiltration membranes

High-purity fructooligosaccharides (FOS) with high economic value have been widely used in the food and medical fields. The use of ceramic nanofiltration (NF) membranes with narrow pore-size distributions have been proven to be a promising strategy for purifying FOS. The preliminary screening of membranes according to the retention rate of each membrane itself is more scientific than basing it only on the molecular weight cut-off. In addition, the yield, purity, membrane flux, and washing water volume of the product should be considered comprehensively. Here, the concentration of FOS feed should be controlled within 100 g·L−1, with the suggested settings for transmembrane pressure, cross-flow velocity, and operating temperature being 0.7 MPa, 1.2 m·s−1, and 60 °C, respectively. The model analysis showed that the NF membrane with a high separation factor and low non-prebiotic sugar rejection rate can obtain a high FOS yield and purity with less leachate addition. Moreover, the ceramic NF membrane can maintain a stable separation performance during the separation process, and the pure water flux can be recovered after cleaning, which has good application prospects in the FOS purification industry.

Study on the preparation method of porous membranes with single pore size distribution and tailored pore sizes by the induced swelling effect of pre-set graft side chains

To improve the sieving accuracy of material separation, it is necessary to develop a porous membrane with tailored pore size and narrow pore size distribution. Polyvinylidene fluoride (PVDF), the mainstream membrane material, is a semi-crystalline polymer. On the basis of the high elastic state of the PVDF molecular chain in the amorphous region at room temperature, a novel method was proposed to prepare porous membranes with single pore size distribution and tailored pore sizes in this paper. First, 1,3-bis (tris(hydroxymethyl)methylamino) propane (Bis-Tris propane) was grafted onto the PVDF-CTFE main chain during casting solution preparation, and the membranes with the thin and nonporous skin layers were prepared by non-solvent-induced phase separation (NIPS), which had almost no water flux. The membrane with the nonporous skin layer produced a water flux of 35.3 L ∙ m−2∙ h−1∙ bar−1 after soaking in the alkaline glycine solution. FTIR and EDX tests demonstrated that small molecular glycine can be guided into the membrane matrix by the affinity with the polar groups on the pre-set side chains, inducing the reactive swelling effect, which led to the formation of new through holes. Subsequently, the membrane with the nonporous skin layer was initially soaked in ethanol to form pores in advance, then the induced reactive swelling of pre-set graft side chains was carried out. The water flux of obtained membrane was significantly up to 96.9 L ∙ m−2∙ h−1∙ bar−1, proving that the pre-pore forming process successfully strengthened the reactive swelling-caused pore generation effect. Furthermore, based on the enhanced swelling-caused pore generation strategy, amino acids with different molecular sizes were induced to the reactive swelling effect in the amorphous regions. The mathematical fitting showed a linear correlation between the average pore size of the membrane and the molar hydration volume of amino acids, and the membrane was single pore size distribution, verifying that controllably tailored membrane pore size can be realized by the reactive swelling effect of the reactive small molecule with different molecular sizes. Compared to some membranes with single pore size distribution prepared by track etching and anodic oxidation method, the membranes prepared by this method had higher water flux. The water contact angle result clarified that the membrane surfaces and pore channels had excellent hydrophilicity. The reactive swelling did not change the crystallinity and porosity, so the mechanical strength of the membrane did not deteriorate.

Designing poly(vinylidene fluoride) membranes with narrow pore size distribution for microplastics removal from water

AbstractMicroplastics have been recognized as a critical threat to the aquatic ecosystem. Membrane separation technology displays great potential to address this issue, while current commonly‐used polymeric microfiltration membranes fall short of high separation efficiency due to their wide pore distribution. A perfectly simple strategy for homoporous membranes fabrication using commercial poly(vinylidene fluoride) (PVDF) was reported in this work, enabling precise removal of microplastics. In this strategy, hydrophilicity of dope solution was enhanced by adding proper amphiphilic surfactants initially, followed by a novelly‐inserted air exposure progress to gently provide water vapor. Both of the two easy steps induced a surface microscopic phase separation to achieve the growth of homopores. Furthermore, the as‐prepared PVDF membrane displayed high surface porosity and bi‐continuous cross‐section structure. As expected, a high rejection (over 97%) towards 500 nm polystyrene microparticles could be achieved along with satisfying water flux of 662 L m−2 h−1 bar−1, which was superior to most current membranes. This work provides not only a new and facile strategy for preparing homoporous membranes employing commercial polymers rather than rarely‐obtained block polymers, but a promising alternative for the efficient separation of aquatic microplastics.

Improvement of persistent hydrophilicity and pore uniformity of polyvinyl chloride ultrafiltration membranes by in-situ crosslinking reaction assisted phase separation

A novel in-situ crosslinking reaction assisted phase separation strategy was proposed for persistent hydrophilization and pore size regulation of polyvinyl chloride (PVC) membranes. In-situ cross-linking between PVC molecular chains was achieved through grafting of 3-aminopropyltrimethoxysilane (APTMS) during the dissolution process and cross-linking reactions between siloxanes in APTMS molecules initiated by the coagulation bath (water). The effect of in-situ crosslinking reaction on the structure, separation and anti-fouling performance of the PVC membranes was studied. Through in-situ crosslinking reaction induced phase separation, the migration and curing of polymer molecular chains in the phase separation process were regulated, which endowed the modified membrane with improved hydrophilicity, higher porosity and narrow pore size distribution. The pure water flux of the obtained membrane increased 3.5 times as much as that of the pure PVC membrane. In addition, the flux recovery rate (FRR) of the obtained membrane was increased by 15.9% and the strength was also increased slightly at the same time. The stability of the membranes was also improved, without chemical agents leaching during filtration, avoiding secondary pollution to our environment.

Effects of sulfonation degree on compatibility and separation performance of polybenzimidazole (PBI)-sulfonated polyphenylenesulfone (sPPSU) blend membranes

The molecular compatibility between polybenzimidazole (PBI) and sulfonated polyphenylsulfone (sPPSU) and their blend membranes for herbicide removal in water reuse and for drug separation in organic solvent nanofiltration (OSN) have been investigated as a function of sulfonation degree in sPPSU. Flat sheet membranes cast from PBI-sPPSU blends with a mass ratio of 1:1 were prepared and then crosslinked by trimesoyl chloride (TMC) at room temperature. The blend made of PBI and 12.7 mol% sPPSU showed high compatibility based on the calculated enthalpy of mixing (ΔHm), measured dope viscosity, phase diagram, and single Tg. The TMC modified membrane cast from this composition also exhibited higher chemical resistance, mechanical stability, narrower pore size and pore size distribution, macrovoid-free structure and better separation performance. All fabricated membranes were evaluated using feeds containing tetracycline (MW = 444 Da) as a model drug in ethanol and pendimethalin (MW = 281.3 Da) as a model herbicide in water. The crosslinked PBI-12.7 mol% sPPSU (12.7C) membrane exhibited rejection of >96% against low-molecular-weight pendimethalin from water and tetracycline from ethanol. It also has the capability to separate mixed solutes, even with small molecular weights. This study illustrates the effectiveness of highly compatible polymer blends with the aid of one-step cross-linking modification for nanofiltration.

Ionic Liquid Templated Ordered Hexagonal Mesoporous Iron Phosphate: A Highly Effective Heterogeneous Catalyst with Remarkable Selectivity for Phenol Hydroxylation Reaction.

A highly organized hexagonal mesoporous iron phosphate framework structure with the designation HMI-41 was successfully synthesized for the first-time in a reproducible way using imidazolium-based ionic liquid as structure directing agent. The unique templating properties of ionic liquid generated a highly ordered well-crystallized mesoporous matrix having high surface area (445 m2g-1), thicker pore wall (2.1 nm) and narrow pore size distribution (3.1 nm). The presence of active sites within a tetrahedral framework structure made the novel HMI-41 catalyst highly effective for phenol hydroxylation in an acidic medium with hydrogen peroxide as the oxidant. The catalyst exhibited outstanding performance, achieving an impressive 80% hydroquinone selectivity and 21% of phenol conversion with a hydroquinone-to-catechol ratio of seven, which is the highest value ever reported.

Enhancement of the Texture & Morphology of Nano γ-Alumina as a Support for Naphtha Reforming Catalyst

The morphology of nano gamma alumina affects the molecule adsorption-desorption phenomena. In this case, manipulating the surface area, pore volume, and pore size by the technique of preparation to control the morphology and textural properties of gamma alumina. Washing of the synthesized boehmite gel with methanol has a significant effect. The co-precipitation method was used to prepare nano gamma alumina, which is involved by adding drop-by-drop ammonium hydroxide and aluminum nitrate nonahydrate solutions to a cetyltrimethylammonium bromide (CTAB) cationic surfactant solution at 30 C and adjust PH to 8. Nitrogen adsorption-desorption analysis (ASAP 2020), Atomic Force Microscope (AFM), and X-Ray Diffraction (XRD) were used to examine the obtained material. Surface area (362 m2/g), pore volume (0.51 cm3/g), pore size (5.2 nm), and narrow pore size distribution were obtained.

Investigating the effect of solid loading on microstructure, mechanical properties, and translucency of highly translucent zirconia ceramics prepared via stereolithography-based additive manufacturing

A study was conducted to explore the potential of 5 mol% yttria-partially stabilized zirconia (5Y-PSZ) ceramics for dental restorations, using stereolithography (SLA) printing technique. Four different solid loadings were established in the ceramic paste systems to study their effects on microstructure, mechanical properties, and translucency. The study examined the rheological behavior and photopolymerization performance of the ceramic pastes with varying solid loadings. Results showed that, an increase in powder concentration resulted in a decrease in cure depth (Cd) and penetration depth (Dp). A narrower pore size distribution was observed in the green bodies with a high solid loading, facilitating the achievement of final densification. The green and sintered densities were highest at 52 vol%, with values of 3.46 ± 0.01 g/cm3 and 6.01 ± 0.02 g/cm3, respectively. Additionally, all of the green strengths exceeded 30 MPa, with a maximum of 35.09 ± 2.02 MPa obtained at 44 vol%. The maximum flexural strength and minimum contrast ratio (CR) value of 746 ± 75 MPa and 0.40 ± 0.01 were achieved at 52 vol% after sintering. No significant differences were observed in the phase composition and hardness of the as-sintered ceramics. Though significant differences were observed in photopolymerization performance, four materials showed similar structural reliability considering Weibull modulus and characteristic strength.

Carbon spheres with ultra-hydrophilic surface and ordered pores on the borderline between micropores and mesopores for improving supercapacitive performance

The unique porous carbon (named AUSH) with superior porosity, wettability, and uniform spherical morphology was successfully prepared using a thermal pretreatment of glucose-derived spherical hydrochar with urea followed by KOH activation. Thermal pretreatment of hydrochar with urea induces nitrogen-containing functional groups and increases sp3-hybridized carbon to improve the surface wettability of hydrochar with KOH solution to facilitate the activation process and thus obtaining the borderline microporous-mesoporous structure. The highly porous AUSH possesses a high surface area (2775.9 m2 g−1) and large pore volume (1.89 cm3 g−1) with narrow pore size distribution (~2 nm). This borderline microporous-mesoporous structure exhibits an ultra-hydrophilic surface to increase the electrochemically active surface area in aqueous electrolytes and thus benefits the charge-storage capacity. The AUSH has higher specific capacitance (354 F g−1 at 1 A g−1), rate capability (264 F g−1 at 50 A g−1), and cycle-life stability in 6 M KOH than other KOH-activated porous carbon materials. The enhanced supercapacitive characteristics are largely attributed to the spherical morphology, hydrophilic surface, and well-developed porosity that bridges the gap in attainable pores between micropores and mesopores for facilitating the ion transport and surface-controlled redox kinetics.

Mesoporous Chromium Catalysts Templated on Halloysite Nanotubes and Aluminosilicate Core/Shell Composites for Oxidative Dehydrogenation of Propane with CO2

The oxidative dehydrogenation of alkanes is a prospective method for olefins production. CO2-assisted propane dehydrogenation over metal oxide catalysts provides an opportunity to increase propylene production with collateral CO2 utilization. We prepared the chromia catalysts on various mesoporous aluminosilicate supports, such as halloysite nanotubes, nanostructured core/shell composites of MCM-41/halloysite (halloysite nanotubes for the core; silica of MCM-41-type for the shell), and MCM-41@halloysite (silica of MCM-41-type for the core; halloysite nanotubes for the shell). The catalysts have been characterized by X-ray fluorescence analysis, low-temperature nitrogen adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of ammonia, transmission electron microscopy with energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The catalysts’ performance in carbon-dioxide-assisted propane dehydrogenation has been estimated in a fixed-bed reactor at atmospheric pressure. The most stable catalyst is Cr/halloysite, having the lowest activity and the largest pore diameter. The catalyst, Cr/MCM-41/HNT, shows the best catalytic performance: having the highest conversion (19–88%), selectivity (83–30%), and space–time yield (4.3–7.1 mol C3H6/kg catalyst/h) at the temperature range of 550–700 °C. The highest space–time yield could be related to the uniform distribution of the chromia particles over the large surface area and narrow pore size distribution of 2–4 nm provided by the MCM-41-type silica and transport channels of 12–15 nm from the halloysite nanotubes.

On the balance between albumin loss and removal of middle molecules in dialyzers

Tuning the pore size distribution of hemodialysis membranes is essential for the membrane’s selectivity and significantly affects the quality of the dialysis treatment. Tailoring the membrane’s molecular weight cut-off appropriately balances the removal of middle-molecular-weight uremic toxins while avoiding albumin loss. This undesirable albumin loss is a potential side effect and concern for clinical use when aiming at increased removal of middle molecular weight molecules (middle molecules). It is hypothesized that control of the position of a narrow pore size distribution allows middle molecule removal while simultaneously counteracting the unwanted albumin loss. This study presents a comprehensive ex-vivo methodology and novel data on the balance of the clearance of middle molecules and albumin loss at different blood and dialysate flow rates using novel dialyzers. The outcomes hold significance for dialysis therapy, while the insights acquired have broader implications for the selectivity of ultrafiltration membranes.The Theranova dialyzer shows the largest clearance for small-middle molecules. Phylther stands out with higher removal of the middle molecule YKL-40 than the other dialyzers but exhibits a significant albumin loss. Theranova demonstrates the best compromise between low albumin loss and good clearances of middle molecules.

Effects of surface hydrophobicity on the removal of F-specific RNA phages from reclaimed water by coagulation and ceramic membrane microfiltration.

Microfiltration (MF) has been widely adopted as an advanced treatment process to reduce suspended solids and turbidity in treated wastewater effluents designated for potable reuse. Although microfilter pores are much larger than viruses, the addition of a coagulant upstream of a microfilter system can achieve stable virus removal. Ceramic membranes have a narrow pore size distribution to achieve the high removal of contaminants. This study aims to evaluate virus log reduction using bench-scale coagulation and ceramic membrane MF. To investigate the effects of differences in net surface hydrophobicity, 18 sewage-derived F-specific RNA phages (FRNAPHs) were used for batch hydrophobicity and coagulation-MF tests. The capability of bench-scale coagulation and ceramic membrane MF under continuous automated long-term operation was tested to remove the lab reference strain MS2 and three selected FRNAPH isolates which varied by surface property. Median virus log reduction values (LRVs) exceeding 6.2 were obtained for all three isolates and MS2. Although coagulation and hydrophobicity were positively correlated, the virus isolate demonstrating the lowest level of hydrophobicity and coagulation (genogroup I) still exhibited a high LRV. Thus, coagulation and ceramic membrane MF systems may serve as viable options for virus removal during water reclamation and advanced treatment.

Inorganic nanoparticles-modified polyvinyl chloride separation membrane and enhanced anti-fouling performance

Porous nanomaterials are important additives in the preparation of high-performance separation membranes. To prepare two nanocomposites, mesoporous silicon dioxide (MCM-41) as a carrier and zinc acetate as a zinc source, Zinc oxide-loaded mesoporous silicon dioxide (ZPP-MCM) was prepared by using polydopamine (PDA) and Polyethylenimine (PEI) as water-soluble ligands, and zinc oxide-loaded mesoporous silicon dioxide (εZI-MCM) were prepared by using iminodiacetic acid (IDA) as water-soluble ligands and coated with ε-poly-l-lysine HCl. The two nanocomposites were blended into polyvinyl chloride (PVC) membranes as modifiers. The results show that the overall porosity of the composite membrane is increased. However, the surface roughness of the composite membrane is decreased with narrow pore size distribution, which was favourable for selective filtration. εZI-MCM nanoparticles can be evenly distributed on the film due to their excellent dispersion, which solves the problem of uneven distribution of nanoparticles on the film, and the surface of the prepared composite film is relatively flat. In addition, introducing the nanoparticles significantly improves the surface hydrophilicity and water flux of the composite membrane. In the experiments of pure water flux and bovine serum albumin (SBA) flux, the flat film with nanoparticles shows higher flux than pure PVC films. The addition of nano-composites further improves the anti-fouling performance and flux recovery ratio of the modified PVC membrane, and the recovery ratio of flux was more than 90%. This work exhibits that Porous nanomaterials have successfully modified the hydrophobic PVC membrane, affording good anti-fouling performance.

Structural transformation doubly triggered by hydrothermal temperature and reaction time in 3D mixed transition metal oxide: Great enhancement of pore size distribution and specific surface area

The three-dimensional (3D) nanostructured binary metal oxides have a massive prospect in energy-related applications owing to their outstanding electrochemical performance and stability. 3D hierarchical tremella-like nickel cobaltite (NiCo2O4) has been successfully synthesized by a hydrothermal method coupled with an annealing treatment process. The effects of temperature and reaction time in hydrothermal process on crystal structure, morphology, particles size, surface area and pore size distribution were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller analysis (BET) and Barrett-Joyner-Halenda (BJH) analysis. The results showed that 3D hierarchical nanoporous structures composed of interconnected thin nanoflakes with thickness of about 20 nm began to form when the mixture was heated for 6 h at 180 °C with considerably high specific surface area of 169.61 m2/g. On the other hand, the highest surface area (203.21 m2/g) and narrowest pore size distribution (9.13 nm) are achieved by the sample heated at a temperature of 160 °C for 12 h. These findings indicated that temperature and reaction time parameters in hydrothermal process play a major role in producing different quality and altered morphological structures of NiCo2O4 powders which later will affect the electrochemical performance of fuel cell.