Free-standing and binder-free porous monolithic electrodes prepared via sol–gel processes

Hasegawa, George

doi:10.1007/s10971-022-05862-5

Cited by 6 publications

(2 citation statements)

References 390 publications

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“…The former group offers extremely high specific surface area when the particle size is reduced down to a range of a few nanometers or less, and hence, intense efforts have been directed at developing nanoparticles composed of various compounds including metals − and metal oxides. − Nevertheless, nanoparticles suffer from their poor durability at elevated temperatures since they are bound to be readily agglomerated and fused with each other, leading to particle growth and thereby exponentially decreasing specific surface area. − In addition, recent studies have highlighted serious concerns about their toxicity risk to living organisms, which is known as “nanotoxicity”. − In general, nanoparticles are deposited on a reliable ceramic support with a relatively low concentration for practical applications. − In the latter group, on the other hand, the specific surface area of porous particles can be enhanced by establishing nanoporosity no matter how large the particle size is, even on a centimeter scale ( i.e. , porous monoliths), though the rational design of hierarchically porous structures is required to allow for efficient mass transport throughout a single porous body. − It should be kept in mind, however, that small pores (typically, micropores and mesopores less than 10 nm) tend to dwindle by crystal growth at high temperatures except for amorphous silica and carbon.…”

Section: Introductionmentioning

confidence: 99%

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO_3-δ Perovskite

Otaguro,

Takeno,

Sugimoto

et al. 2023

Chem. Mater.

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Introduction of open mesoporosity into microparticles with a robust morphology provides a high active surface area together with good thermal stability and shows benefit in various applications at high temperatures. Recently, nonstoichiometric Sr–Fe perovskites with an oxygen release/absorption capability have attracted interests as an oxidation catalyst operated at elevated temperatures. Here, we demonstrate the topotactic synthesis approach to fabricate mesoporous microparticles of SrFeO3−δ with monodispersibility as well as rhombic dodecahedral morphology from the correspondent hydrogarnet precursor (Sr3Fe2(OH)12) prepared by the hydrothermal reaction. Relationship between synthetic conditions and the formed crystal morphology has been systematically explored, which discloses that the crystallization of hydrogarnet can take place at as low as 40 °C. On heating, the dehydration of Sr3Fe2(OH)12 gives rise to phase separation into Sr(OH)2 and SrFeO3−δ via a transient phase of “oxyhydrogarnet”. Selective removal of the Sr(OH)2-derived phase leaves three-dimensionally interconnected mesopores in individual polyhedral microparticles. Meanwhile, further increase of the heat-treatment temperature sets off the reaction between the two separated phases, ending up in nonporous polyhedral particles composed of Ruddlesden–Popper-type layered perovskite (Sr3Fe2O7−δ) at 1200 °C. The mesoporous SrFeO3−δ polyhedral microparticles exhibit an enhanced catalytic performance of CO oxidation superior to the nonporous counterparts, which is associated with the stimulated oxygen release capability owing to mesoporosity rather than the oxygen uptake rate.

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Section: Introductionmentioning

confidence: 99%

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO_3-δ Perovskite

Otaguro,

Takeno,

Sugimoto

et al. 2023

Chem. Mater.

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“…Additionally, continuous gas evolution during electrochemical reactions may also result in detachment of the electrocatalysts. Recently, various binder-free integrated electrocatalytic electrodes have been reported, including electrocatalysts that directly grow on conductive substrates [25,26] or generate free-standing films [27,28]. In comparison with the conventional powderbased electrodes, the integrated electrodes (IEs) with convenient and time-efficient preparation procedures have shown excellent activity and stability [24,25].…”

Section: Introductionmentioning

confidence: 99%

Towards a new avenue for rapid synthesis of electrocatalytic electrodes via laser-induced hydrothermal reaction for water splitting

Sha,

Zhu,

Huang

et al. 2023

Int. J. Extrem. Manuf.

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Electrochemical production of hydrogen from water requires the development of electrocatalysts that are active, stable, and low-cost for water splitting. In comparison with conventional powder-based electrode preparation, synthesis of binder-free electrocatalytic integrated electrodes is highly desirable to improve the catalytic activity and long-term stability for large-scale applications of electrocatalysts. Herein, we demonstrate a laser-induced hydrothermal (LIHR) technique to grow NiMoO4 nanosheets on Nickel foam, which is then calcined under H2/Ar mixed gases to prepare the integrated electrode IE-NiMo-LR. This electrode exhibits superior hydrogen evolution reaction performance, requiring overpotentials of 59, 116 and 143 mV to achieve current densities of 100, 500 and 1000 mA cm-2. During the 350 h chronopotentiometry test at current densities of 100 and 500 mA cm-2, the overpotential remained essentially unchanged. In addition, NiFe-layered double hydroxide grown on Ni foam is fabricated with same LIHR method and coupled with IE-NiMo-IR to achieve water splitting. This combination exhibits excellent durability under industrial current density. The energy consumption and production efficiency of LIHR method are systematically compared with conventional hydrothermal method. The LIHR method significantly improved the production rate by over 19 times, while consuming only 27.78% of the total energy required by conventional hydrothermal method to achieve the same production.

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Morphological Control and Mechanical Properties of Porous Phenolic Resins Derived from Poly(4‐Vinylphenol): Effects of Molecular Weight and Polydispersity of Prepolymer

Hasegawa,

Takano,

Hiei

et al. 2024

Adv Eng Mater

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Improvement of mechanical stability for porous polymer monoliths is one of the prime concerns as represented by the long‐standing research efforts on resorcinol‐formaldehyde (RF) aerogels. To this end, it is imperative not only to tailor mechanically robust porous morphology but also to design macromolecular structure of polymer scaffolds. Previously, we have developed porous RF gels showing a unique mechanical feature combining high mechanical strength and outstanding flexibility against uniaxial compression. Comparison of mechanical properties between the porous gels with varied morphologies has elucidated the influence of porous structure, whereas effects of macromolecular structure still remain elusive. Herein, we have fabricated a series of macroporous phenolic resins from three types of linear prepolymers with phenol pendant groups, poly(4‐vinylphenol) or poly(4‐hydroxystyrene), which differ in molecular‐weight properties, by the sol–gel process in conjunction with spinodal decomposition. The difference in gelation and phase separation behaviors observed for the discrete systems indicates the dissimilar cross‐linked networks developed in the respective gels, which consequently influence the mechanical strength and flexibility against uniaxial compression. This study also demonstrates the improvement of mechanical features by thermal treatment for the porous monoliths derived from the high‐molecular‐weight prepolymer with a view to the application in mechanical energy absorption.

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Free-standing and binder-free porous monolithic electrodes prepared via sol–gel processes

Cited by 6 publications

References 390 publications

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO_3-δ Perovskite

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO_3-δ Perovskite

Towards a new avenue for rapid synthesis of electrocatalytic electrodes via laser-induced hydrothermal reaction for water splitting

Morphological Control and Mechanical Properties of Porous Phenolic Resins Derived from Poly(4‐Vinylphenol): Effects of Molecular Weight and Polydispersity of Prepolymer

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Free-standing and binder-free porous monolithic electrodes prepared via sol–gel processes

Cited by 6 publications

References 390 publications

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO3-δ Perovskite

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO3-δ Perovskite

Towards a new avenue for rapid synthesis of electrocatalytic electrodes via laser-induced hydrothermal reaction for water splitting

Morphological Control and Mechanical Properties of Porous Phenolic Resins Derived from Poly(4‐Vinylphenol): Effects of Molecular Weight and Polydispersity of Prepolymer

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Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO_3-δ Perovskite

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO_3-δ Perovskite