Photoinduced electron transfer in semiconductor–clay binary nanosheet colloids controlled by clay particles as a turnout switch

Nakato, Teruyuki; Terada, Shinya; Ishiku, Tatsuya; Abe, Shunnosuke; Kamimura, Sunao; Mouri, Emiko; Ohno, Teruhisa

doi:10.1016/j.apcatb.2018.09.047

Cited by 10 publications

(4 citation statements)

References 43 publications

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“…In fact, a series of photofunctions have been found in the binary colloids of niobate and hectorite clay nanosheets, including photoinduced charge separation 56 and decelerated photocatalytic decomposition of a cationic dye, 58 and improved photocatalytic hydrogen evolution over niobate nanosheets has been influenced in the presence of clay nanosheets. 59 Because these specific photochemical reactions originate from the mesoscopic phase-separated structure of the niobate−clay binary colloids, on-demand manipulation of the colloidal structure, such as assembly and disassembly of nanosheets, should enable us to design on-demand photochemical functions. Nevertheless, such an attempt has yet been achieved.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Significance of niobate–clay binary nanosheet colloids has been demonstrated by the characteristic photochemical behavior of this binary system. − Organic cations are selectively adsorbed onto clay nanosheets. , Because the niobate nanosheets are photocatalytically active wide band gap semiconductor, the mesoscopic-scale phase-separation of the binary colloids induces spatial separation of two functional moieties; the photocatalytically active niobate nanosheets and the photochemically inert and optically transparent clay nanosheets which carry functional organic cations such as dyes. In fact, a series of photofunctions have been found in the binary colloids of niobate and hectorite clay nanosheets, including photoinduced charge separation and decelerated photocatalytic decomposition of a cationic dye, and improved photocatalytic hydrogen evolution over niobate nanosheets has been influenced in the presence of clay nanosheets . Because these specific photochemical reactions originate from the mesoscopic phase-separated structure of the niobate–clay binary colloids, on-demand manipulation of the colloidal structure, such as assembly and disassembly of nanosheets, should enable us to design on-demand photochemical functions.…”

Section: Introductionmentioning

confidence: 99%

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Electrically Induced Alignment of Semiconductor Nanosheets in Niobate–Clay Binary Nanosheet Colloids toward Significantly Enhanced Photocatalysis

et al. 2021

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Aqueous binary colloids of niobate and clay nanosheets, prepared by the exfoliation of their mother layered crystals, are unique colloidal systems characterized by the separation of niobate and clay nanosheet phases, where niobate nanosheets form liquid crystalline domains with the size of several tens of micrometers among isotropically dispersed clay nanosheets. The binary colloids show unusual photocatalytic reactions because of the spatial separation of photocatalytically active niobate and photochemically inert clay nanosheets. The present study shows structural conversion of the binary colloids with an external electric field, resulting in the onsite alignment of colloidal nanosheets to improve the photocatalytic performance of the system. The colloidal structure is reshaped by the growth of liquid crystalline domains of photocatalytic niobate nanosheets and by their electric alignment. Niobate nanosheets are assembled by the domain growth process and then aligned by AC voltage, although clay nanosheets do not respond to the electric field. Photocatalytic decomposition of the cationic rhodamine 6G dye, which is selectively adsorbed on clay nanosheets, is examined for the niobate−clay binary nanosheet colloids with or without domain growth and electric field. The fastest decomposition is observed for the electrically aligned colloid without the domain growth, whereas the sample with the domain growth and without the electric alignment shows the slowest decomposition. The results demonstrate the improvement of the photocatalytic performance by changing the colloidal structure, even though the sample composition is the same.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrically Induced Alignment of Semiconductor Nanosheets in Niobate–Clay Binary Nanosheet Colloids toward Significantly Enhanced Photocatalysis

et al. 2021

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“…However, this system is not in a glass state but fluid. The dynamic nature allows particle diffusion in the colloid to achieve controllable photoinduced electron transfer, electron accumulation, and photocatalytic reactions between photocatalytically active NB nanosheets and electron-accepting molecules loaded on clay particles. − Thus, our NB–clay binary colloid is a rare example of hierarchically organized multicomponent photofunctional inorganic liquid crystalline colloid with mesoscopic multiphase structures retaining high fluidity of particles. , Although each phase is held at a mesoscopic scale to work as a dynamic functional unit, the whole structure of NB–clay binary system has only been qualitatively characterized by spectroscopic and small-angle neutron scattering measurements.…”

Section: Introductionmentioning

confidence: 99%

Mesoscopic Architectures Made of Electrically Charged Binary Colloidal Nanosheets in Aqueous System

Nakato¹,

Takahashi

Terada³

et al. 2019

Langmuir

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Inorganic layered materials can be converted to colloidal liquid crystals through exfoliation into inorganic nanosheets, and binary nanosheet colloids exhibit rich phase behavior characterized by multiphase coexistence. In particular, niobate–clay binary nanosheet colloids are characterized by phase separation at a mesoscopic (∼several tens of micrometers) scale whereas they are apparently homogeneous at a macroscopic scale. Although the mesoscopic structure of the niobate–clay binary colloid is advantageous to realize unusual photochemical functions, the structure itself has not been clearly demonstrated in real space. The present study investigated the structure of niobate–clay binary nanosheet colloids in detail. Four clay nanosheets (hectorite, saponite, fluorohectorite, and tetrasilisic mica) with different lateral sizes were compared. Small-angle X-ray scattering (SAXS) indicated lamellar ordering of niobate nanosheets in the binary colloid. The basal spacing of the lamellar phase was reduced by increasing the concentration of clay nanosheets, indicating the compression of the liquid crystalline niobate phase by the isotropic clay phase. Scattering and fluorescence microscope observations using confocal laser scanning microscopy (CLSM) demonstrated the phase separation of niobate and clay nanosheets in real space. Niobate nanosheets assembled into domains of several tens of micrometers whereas clay nanosheets were located in voids between the niobate domains. The results clearly confirmed the spatial separation of two nanosheets and the phase separation at a mesoscopic scale. Distribution of clay nanosheets is dependent on the employed clay nanosheets; the nanosheets with large lateral length are more localized or assembled. This is in harmony with larger basal spacings of niobate lamellar phase for large clay particles. Although three-dimensional compression of the niobate phase by the coexisting clay phase was observed at low clay concentrations, the basal spacing of niobate phase was almost constant irrespective of niobate concentrations at high clay concentrations, which was ascribed to competition of compression by clay phase and restoring of the niobate phase.

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“…Meanwhile, hexaniobate K4Nb6O17 is a typical lamellar semiconductor material, which is composed of stacked asymmetrical Nb6O17 4layers [11,12]. K4Nb6O17 possess remarkable photocatalytic activity [11,13,14] and the photocatalytic performance is further enhanced by exfoliating the bulk K4Nb6O17 crystals into 2D nanosheets [15,16,17,18] because effective surface area drastically increases by the exfoliation. However, the niobate nanosheets aggregate easily in the presence of salt etc., resulting in decreased catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Photocatalytic Niobate Nanosheet/Polymer Composite Microgel Particles through Microfluidic Approach

Nishi

Yang

et al. 2019

KEM

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Polydimethylacrylamide (PDMA) microgels and niobate nanosheet/PDMA composite microgels were fabricated by using a microfluidic device. Morphologies and sizes of the composite microgels were tuned by adjusting synthetic conditions such as viscosity of oil phases, hydrophilicity and concentration of surfactants, and flow rates of oil phase and water phase. Furthermore, it was found that the dispersion of nanosheets was better when the composite microgels were synthesized by photopolymerization compared to redox polymerization.

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Photoinduced electron transfer in semiconductor–clay binary nanosheet colloids controlled by clay particles as a turnout switch

Cited by 10 publications

References 43 publications

Electrically Induced Alignment of Semiconductor Nanosheets in Niobate–Clay Binary Nanosheet Colloids toward Significantly Enhanced Photocatalysis

Electrically Induced Alignment of Semiconductor Nanosheets in Niobate–Clay Binary Nanosheet Colloids toward Significantly Enhanced Photocatalysis

Mesoscopic Architectures Made of Electrically Charged Binary Colloidal Nanosheets in Aqueous System

Synthesis of Photocatalytic Niobate Nanosheet/Polymer Composite Microgel Particles through Microfluidic Approach

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