Microwave-assisted hydrothermal synthesis of sulfonated TiO2-GO core–shell solid spheres as heterogeneous esterification mesoporous catalyst for biodiesel production

Soltani, Soroush; Khanian, Nasrin; Choong, Thomas Shean Yaw; Zhao, Yue

doi:10.1016/j.enconman.2021.114165

Cited by 39 publications

(8 citation statements)

References 56 publications

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“…TiO 2 NFs display six diffraction peaks at 25.3° (101), 37.0° (004), 48.1° (200), 53.9° (105), 55.1° (211), 62.8° (204), which are in accordance with the anatase phase of TiO 2 (PDF#01-089-4921). [29,30] In addition, all these membranes exhibited similar surface morphologies and NF diameters (Figure S7b,c, Supporting Information). Our previous studies verified that the diameter was mainly affected by the electric field force, while the crystallinity was affected by the sintering temperature.…”

Section: Materials Synthesis and Flexure Demonstration Of Tio 2 Cryst...mentioning

confidence: 81%

Superior Flexibility in Oxide Ceramic Crystal Nanofibers

et al. 2021

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structures of crystallites. [3][4][5][6] On a larger scale (i.e., >100 nm), ceramic crystal products are often hard and brittle, which was mainly affected by the structural dimensions and mesoscopic structures of the ceramic crystallites. [7][8][9] It has been reported that ceramic films were actually flexible when they were extremely thin (ex. several nanometers), and the flexibility was directly determined by the vibrations of chemical bonds. [10][11][12][13] Calculations have shown that the vibration energies of TiO, ZrO, and SiO bonds in inorganic crystals were much lower than those of CC, CO and CH bonds in organic polymers. [14] Generally, the high bonding density of ceramic crystals made ceramics hard, while crystal defects and amorphous oxides could produce soft mechanical responses. [15,16] Recently, several self-supporting oxide ceramic nanofibers (NFs) were fabricated by electrospinning. [17][18][19][20] Unfortunately, these NFs were not flexible, and they broke easily during stretching. Researchers tried to dop carbon or a second oxide phase into NFs to enhance the flexibility, but these NFs were still brittle due to the uncontrollable assembly of crystallites, which created randomly-arranged crystals with disorder grain boundaries and fine cracks. [21,22] Both of these structures were sensitive to rupture and rapidly aggregate into coarse cracks when NFs were subjected to external forces. [23][24][25] Here, we define "flexible" electrospun NFs as those in which the individual NF is compliant (small elastic modulus) and strong (high yield strength), as opposed to stiff and weak. Once these flexible NFs stagger randomly together to form membranes, they can undergo large deformation without fracture and thus demonstrate silk-like softness property. However, the membrane thickness should be considered when reporting the flexibility of such ceramic NF membranes.Here, we explore how the mesoscopic structure of such crystallites can be designed to create flexible electrospun ceramic NFs and propose a reasonable expression of ceramic flexibility when considering the influence of thickness. Inspired by the "Magic Ruler Puzzle" that is generally composed of a rigid triangular prism (brick) and soft spring (mortar) in an ordered arrangement, we fabricated superior flexible TiO 2 NFs with similar brick-and-mortar structures by combining ball-milling and curved-drafting strategies with traditional sol-gel electrospinning. This method produced flexible TiO 2 NF membranes that could fold without tearing, and the individual NF Oxide crystal ceramics are commonly hard and brittle, when they are bent they typically fracture. Such mechanical response limits the use of these materials in emerging fields like wearable electronics. Here, a polymerinduced assembly strategy is reported to construct orderly assembled TiO 2 crystals into continuous nanofibers that are stretchable, bendable, and even knottable. Ball-milling the spinning sol and curved-drafting the electrospun nanofibers significantly improve the molecula...

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Section: Materials Synthesis and Flexure Demonstration Of Tio 2 Cryst...mentioning

confidence: 81%

Superior Flexibility in Oxide Ceramic Crystal Nanofibers

et al. 2021

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“…In general, impregnation of heterogeneous catalysts on supported metal oxides leads to the stochastic distribution of the size and spatial location of the active NPs within the catalyst volume [ 60 ]. Additionally, CSNs can be engineered via additional synthesis following hydrothermal [ 61 , 62 , 63 ] microemulsion [ 64 , 65 , 66 , 67 ], ball milling [ 68 , 69 ] or ion exchange [ 70 , 71 ] technique. Such additional synthesis steps are important to tailor the water-to-surfactant ratio, thus resulting in a small and narrow particle size distribution inside the shell cage.…”

Section: Approaches To the Synthesis Of Core-shell Catalysts For Co ...mentioning

confidence: 99%

Recent Application of Core-Shell Nanostructured Catalysts for CO2 Thermocatalytic Conversion Processes

et al. 2022

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Carbon-intensive industries must deem carbon capture, utilization, and storage initiatives to mitigate rising CO2 concentration by 2050. A 45% national reduction in CO2 emissions has been projected by government to realize net zero carbon in 2030. CO2 utilization is the prominent solution to curb not only CO2 but other greenhouse gases, such as methane, on a large scale. For decades, thermocatalytic CO2 conversions into clean fuels and specialty chemicals through catalytic CO2 hydrogenation and CO2 reforming using green hydrogen and pure methane sources have been under scrutiny. However, these processes are still immature for industrial applications because of their thermodynamic and kinetic limitations caused by rapid catalyst deactivation due to fouling, sintering, and poisoning under harsh conditions. Therefore, a key research focus on thermocatalytic CO2 conversion is to develop high-performance and selective catalysts even at low temperatures while suppressing side reactions. Conventional catalysts suffer from a lack of precise structural control, which is detrimental toward selectivity, activity, and stability. Core-shell is a recently emerged nanomaterial that offers confinement effect to preserve multiple functionalities from sintering in CO2 conversions. Substantial progress has been achieved to implement core-shell in direct or indirect thermocatalytic CO2 reactions, such as methanation, methanol synthesis, Fischer–Tropsch synthesis, and dry reforming methane. However, cost-effective and simple synthesis methods and feasible mechanisms on core-shell catalysts remain to be developed. This review provides insights into recent works on core-shell catalysts for thermocatalytic CO2 conversion into syngas and fuels

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“…Microwave-assisted synthesis of ZnO nanoparticles is a promising technique for fabricating nanostructures within a controlled environment reliably, less energy consumption and cost-effectively. [25][26][27] Moreover, this technique is highly adjustable when nanostructures of particular types are to be synthesized for specic commercial purposes. 28 Recently, the phytochemical method of synthesizing metal oxide nanoparticles has been gaining huge interest owing to the eco-friendliness, low cost, non-toxicity to humans, convenience of synthesis, and bio-inspiration of this method.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%