Biopolymer colloids for controlling and templating inorganic synthesis

Biopolymers and biopolymer colloids can act as controlling agents and templates not only in many processes in nature, but also in a wide range of synthetic approaches. Inorganic materials can be either synthesized ex situ and later incorporated into a biopolymer structuring matrix or grown in situ in the presence of biopolymers. In this review, we focus mainly on the latter case and distinguish between the following possibilities: (i) biopolymers as controlling agents of nucleation and growth of inorganic materials; (ii) biopolymers as supports, either as molecular supports or as carrier particles acting as cores of core–shell structures; and (iii) so-called “soft templates”, which include on one hand stabilized droplets, micelles, and vesicles, and on the other hand continuous scaffolds generated by gelling biopolymers.

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Recent Advances in Sequential Infiltration Synthesis (SIS) of Block Copolymers (BCPs)

Nanomaterials ◽

10.3390/nano11040994 ◽

2021 ◽

Vol 11 (4) ◽

pp. 994

Author(s):

Eleonora Cara ◽

Irdi Murataj ◽

Gianluca Milano ◽

Natascia De Leo ◽

Luca Boarino ◽

...

Keyword(s):

Block Copolymers ◽

Large Scale ◽

Inorganic Materials ◽

Ex Situ ◽

Selective Incorporation ◽

Microelectronics Industry ◽

Self Assembled ◽

Definition Of ◽

Synthetic Approaches

In the continuous downscaling of device features, the microelectronics industry is facing the intrinsic limits of conventional lithographic techniques. The development of new synthetic approaches for large-scale nanopatterned materials with enhanced performances is therefore required in the pursuit of the fabrication of next-generation devices. Self-assembled materials as block copolymers (BCPs) provide great control on the definition of nanopatterns, promising to be ideal candidates as templates for the selective incorporation of a variety of inorganic materials when combined with sequential infiltration synthesis (SIS). In this review, we report the latest advances in nanostructured inorganic materials synthesized by infiltration of self-assembled BCPs. We report a comprehensive description of the chemical and physical characterization techniques used for in situ studies of the process mechanism and ex situ measurements of the resulting properties of infiltrated polymers. Finally, emerging optical and electrical properties of such materials are discussed.

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Selenium– and tellurium–halogen reagents

Physical Sciences Reviews ◽

10.1515/psr-2018-0060 ◽

2018 ◽

Vol 3 (12) ◽

Cited By ~ 1

Author(s):

Tristram Chivers ◽

Risto S. Laitinen

Keyword(s):

Oxidation State ◽

Halogen Bond ◽

The Other ◽

Oxidation States ◽

Alkyl Aryl ◽

Organic Selenium ◽

Formal Oxidation State ◽

Wide Range ◽

Inorganic And Organic

Abstract Selenium and tellurium form binary halides in which the chalcogen can be in formal oxidation states (IV), (II) or (I). They are versatile reagents for the preparation of a wide range of inorganic and organic selenium and tellurium compounds taking advantage of the reactivity of the chalcogen–halogen bond. With the exception of the tetrafluorides, the tetrahalides are either commercially available or readily prepared. On the other hand, the low-valent species, EX2 (E = Se, Te; X = Cl, Br) and E2X2 (E = Se, Te; X = Cl, Br) are unstable with respect to disproportionation and must be used as in situ reagents. Organoselenium and tellurium halides are well-known in oxidation states (IV) and (II), as exemplified by REX3, R2EX2 and REX (R = alkyl, aryl; E = Se, Te; X = F, Cl, Br, I); mixed-valent (IV/II) compounds of the type RTeX2TeR are also known. This chapter surveys the availability and/or preparative methods for these widely used reagents followed by examples of their applications in synthetic inorganic and organic selenium and tellurium chemistry. For both the binary halides and their organic derivatives, the discussion is subdivided according to the formal oxidation state of the chalcogen.

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In situ X-ray Diffraction Investigation of the Crystallisation of Perfluorinated Ce(IV)-based Metal-Organic Frameworks with UiO-66 and MIL-140 architectures

10.26434/chemrxiv.13252544 ◽

2020 ◽

Author(s):

Stephen Shearan ◽

Jannick Jacobsen ◽

Ferdinando Costantino ◽

Roberto D’Amato ◽

Dmitri Novikov ◽

...

Keyword(s):

Crystal Growth ◽

Metal Organic Frameworks ◽

Building Blocks ◽

Nucleation And Growth ◽

X Ray Diffraction ◽

X Ray ◽

Rate Determining Step ◽

Wide Range ◽

Metal Organic

We report on the results of a thorough in situ synchrotron powder X-ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated Ce(IV)-based metal-organic frameworks (MOFs), analogues of the already well investigated Zr(IV)-based UiO-66 and MIL-140A, namely, F4_UiO-66(Ce) and F4_MIL-140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as building blocks, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds in situ in a wide range of conditions, varying parameters such as temperature, amount of the protonation modulator nitric acid (HNO3) and amount of the coordination modulator acetic acid (AcOH). When only HNO3 is present in the reaction environment, F4_MIL-140A(Ce) is obtained as a pure phase. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C, whereas the modulator influences nucleation and crystal growth to a similar extent. Upon addition of AcOH to the system, alongside HNO3, mixed-phased products, consisting of F4_MIL-140A(Ce) and F4_UiO-66(Ce), are obtained. In these conditions, F4_UiO-66(Ce) is always formed faster and no interconversion between the two phases occurs. In the case of F4_UiO-66(Ce), crystal growth is always the rate determining step. An increase in the amount of HNO3 slows down both nucleation and growth rates for F4_MIL-140A(Ce), whereas nucleation is mainly affected for F4_UiO-66(Ce). In addition, a higher amount HNO3 favours the formation of F4_MIL-140A(Ce). Similarly, increasing the amount of AcOH leads to slowing down of the nucleation and growth rate, but favours the formation of F4_UiO-66(Ce). The pure F4_UiO-66(Ce) phase could also be obtained when using larger amounts of AcOH in the presence of minimal HNO3. Based on these in situ results, a new optimised route to achieving a pure, high quality F4_MIL-140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.

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Nucleation and Growth of Supported Metal Clusters at Defect Sites on Mgo and NaCl (001) Surfaces: The Cases of Pd and Ag

MRS Proceedings ◽

10.1557/proc-570-51 ◽

1999 ◽

Vol 570 ◽

Cited By ~ 5

Author(s):

J. A. Venables ◽

G. Haas ◽

H. Brune ◽

J.H. Harding

Keyword(s):

Deposition Temperature ◽

Metal Clusters ◽

Variable Temperature ◽

Nucleation And Growth ◽

Force Microscopy ◽

Atomic Force ◽

Defect Sites ◽

Wide Range ◽

Adsorption Surface

ABSTRACTNucleation and growth of metal clusters at defect sites is discussed in terms of rate equation models, which are applied to the cases of Pd and Ag on MgO(001) and NaCl(001) surfaces. Pd/MgO has been studied experimentally by variable temperature atomic force microscopy (AFM). The island density of Pd on Ar-cleaved surfaces was determined in-situ by AFM for a wide range of deposition temperature and flux, and stays constant over a remarkably wide range of parameters; for a particular flux, this plateau extends from 200 K ≤ T ≤ 600 K, but at higher temperatures the density decreases. The range of energies for defect trapping, adsorption, surface diffusion and pair binding are deduced, and compared with earlier data for Ag on NaCl, and with recent calculations for these metals on both NaCl and MgO

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Ultra-small MnCo2O4 nanocrystals decorated on nitrogen-enriched carbon nanofibers as oxygen cathode for Li-O2 batteries

Functional Materials Letters ◽

10.1142/s1793604720510352 ◽

2020 ◽

Vol 13 (06) ◽

pp. 2051035

Author(s):

Xiaoping Jiang ◽

Ronghua Wang ◽

Ning Hu ◽

Chaohe Xu

Keyword(s):

Particle Size ◽

Cathode Materials ◽

Nitrogen Doping ◽

Carbon Nanofiber ◽

Nucleation And Growth ◽

Ex Situ ◽

Aprotic Electrolyte ◽

High Level ◽

Oxygen Cathode

Ultra-small MnCo2O4 nanocrystals/nitrogen enriched carbon nanofiber composites, with particle size as small as 2–4[Formula: see text]nm and nitrogen content as high as [Formula: see text][Formula: see text]at.%, were designed and used as oxygen cathode materials for Li-O2 batteries, with an aprotic electrolyte. Via an in-situ nucleation and growth, the morphology, size and distribution of MnCo2O4 nanocrystals were well controlled on surface of nanofibers, with strong interfacial interactions between the two components. Benefitting from the unique microstructure and high-level nitrogen doping, the MnCo2O4/NCF composite can deliver discharge and charge capacities of 4147.8 and 3842.8[Formula: see text]mAh/g as oxygen cathode materials, and columbic efficiencies are about 92.6%. More importantly, the discharge products can completely decompose in charging process as evidenced by an ex-situ FESEM investigation, while for pure NCF cathode, particle and plate-like Li2O2 were still observed on its surface, which confirmed that the MnCo2O4/NCF composite has a superior electrocatalytic activity that that of NCF.

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In Situ Studies of the Processing of Sol-Gel Produced Amorphous Materials Using Xanes, Saxs and Curved Image Plate XRD

MRS Proceedings ◽

10.1557/proc-590-119 ◽

1999 ◽

Vol 590 ◽

Author(s):

DM Pickup ◽

G Mountjoy ◽

RJ Newport ◽

ME Smith ◽

GW Wallidge ◽

...

Keyword(s):

Amorphous Materials ◽

Sol Gel ◽

Heat Treatments ◽

Silica Gels ◽

Ex Situ ◽

High Count ◽

X Ray ◽

Image Plate ◽

Wide Range

ABSTRACTSol-gel produced mixed oxide materials have been extensively studied using conventional, ex situ structural techniques. Because the structure of these materials is complex and dependent on preparation conditions, there is much to be gained from in situ techniques: the high brightness of synchrotron x-ray sources makes it possible to probe atomic structure on a short timescale, and hence in situ. Here we report recent results for mixed titania- (and some zirconia-) silica gels and xerogels. Titania contents were in the range 8–18 mol%, and heat treatments up to 500°C were applied. The results have been obtained from intrinsically rapid synchrotron x-ray experiments: i) time-resolved small angle scattering, using a quadrant detector, to follow the initial stages of aggregation between the sol and the gel; ii) the use of a curved image plate detector in diffraction, which allowed the simultaneous collection of data across a wide range of scattering at high count rate, to study heat treatments; and iii) x-ray absorption spectroscopy to explore the effects of ambient moisture on transition metal sites.

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In Situ Synchrotron X-ray Absorption Experiments and Modelling of the Growth Rates of Electrochemically Deposited ZnO Nanostructures

MRS Proceedings ◽

10.1557/proc-1017-dd12-16 ◽

2007 ◽

Vol 1017 ◽

Cited By ~ 2

Author(s):

Bridget Ingham ◽

Benoit N. Illy ◽

Jade R. Mackay ◽

Stephen P. White ◽

Shaun C. Hendy ◽

...

Keyword(s):

Growth Rates ◽

High Resolution Electron Microscopy ◽

Ex Situ ◽

X Ray ◽

Deposition Parameters ◽

Wide Range ◽

Electrochemically Deposited ◽

Electrochemical Current ◽

X Ray Absorption

AbstractZnO is known to produce a wide variety of nanostructures that have enormous scope for optoelectronic applications. Using an aqueous electrochemical deposition technique, we are able to tightly control a wide range of deposition parameters (Zn2+ concentration, temperature, potential, time) and hence the resulting deposit morphology. By simultaneously conducting synchrotron x-ray absorption spectroscopy (XAS) experiments during the deposition, we are able to directly monitor the growth rates of the nanostructures, as well as providing direct chemical speciation of the films. In situ experiments such as these are critical to understanding the nucleation and growth of such nanostructures.Recent results from in situ XAS synchrotron experiments demonstrate the growth rates as a function of potential and Zn2+ concentration. These are compared with the electrochemical current density recorded during the deposition, and the final morphology revealed through ex situ high resolution electron microscopy. The results are indicative of two distinct growth regimes, and simultaneous changes in the morphology are observed.These experiments are complemented by modelling the growth of the rods in the transport-limited case, using the Nernst-Planck equations in 2 dimensions, to yield the growth rate of the volume, length, and radius as a function of time.

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In situ Mössbauer Study of the Passive Layer Formed on the Iron Anode in Alkaline Electrolyte

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19992044 ◽

1999 ◽

Vol 64 (12) ◽

pp. 2044-2060 ◽

Cited By ~ 8

Author(s):

Karel Bouzek ◽

Martin Nejezchleba

Keyword(s):

Mössbauer Spectra ◽

Sodium Hydroxide Solution ◽

Passive Layer ◽

Iron Electrode ◽

Ex Situ ◽

Anode Surface ◽

Alkaline Electrolyte ◽

Mossbauer Spectra ◽

Wide Range

In situ Mössbauer spectra of the iron electrode at anodic potential were measured in sodium hydroxide solution over a wide range of concentrations (0.1 - 14 mol l-1). It was found that the in situ Mössbauer spectra exhibit generally one sextet and one doublet corresponding to the oxide layer on the anode surface. Parameters of these spectra show only minor variations within the electrolyte concentration range of 0.1 - 7 M NaOH. A pronounced change in the spectra was observed in 14 M NaOH. The major processes taking place in the anode surface layer are based on the break-down of protective properties of the passive layer, incipient intense metal dissolution and subsequent oxidation. Important differences were also found between in situ and ex situ spectra measurements.

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In-situ AFM study of the crystallization and pH-dependent stability of ZnO(0001)-Zn surfaces

MRS Proceedings ◽

10.1557/proc-1035-l13-02 ◽

2007 ◽

Vol 1035 ◽

Author(s):

Markus Valtiner ◽

Guido Grundmeier

Keyword(s):

Electrolyte Solutions ◽

Ex Situ ◽

Chemical Cleaning ◽

Single Crystalline ◽

Afm Imaging ◽

Wide Range ◽

Wet Chemical ◽

Ph Dependent ◽

Crystalline Surfaces

AbstractPolar ZnO(0001)-Zn surfaces can be prepared as very well defined and single crystalline surfaces by hydroxide stabilization simply by introducing hydroxides via a wet chemical cleaning step. Within this proceeding we present an in-situ AFM imaging of the crystallization process. The pH dependent stability of the resulting hydroxide-stabilized surfaces was further investigated by means of an ex-situ LEED approach. These investigations show, that it is possible to obtain high quality single crystalline ZnO(0001)-Zn surfaces in a simple way. Moreover, these surfaces turned out to be very stable within a wide range of pH values between 11 and 3 of NaClO4 based 1mM electrolyte solutions.

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A sub-kiloparsec-scale view of un-lensed submillimeter galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319009074 ◽

2019 ◽

Vol 15 (S352) ◽

pp. 287-290

Author(s):

Ken-ichi Tadaki ◽

Daisuke Iono

Keyword(s):

Surface Density ◽

Gravitational Instability ◽

Effective Radius ◽

The Other ◽

Ex Situ ◽

Submillimeter Galaxies ◽

The Galaxy ◽

Central Regions ◽

Kinematic Properties

AbstractSubmillimeter galaxies at z > 3 building up their central cores through compact starbursts with an effective radius of 1–2 kpc. Our ALMA high-resolution observations reveal off-center gas clumps in a submillimeter galaxy at z = 4.3, COSMOS-AzTEC-1, as well as a rotation-dominated disk. Exploiting the kinematic properties and the spatial distribution of gas mass surface density, we find that the starburst disk is gravitationally unstable. This result is consistent with a scenario where in-situ clumps are formed through disk instability. On the other hand, we find evidence for an ex-situ clump that does not corotate with the starburst disk. The accretion of such a non-corotating clump could stimulate violent disk instability, driving gas inflows into the central regions of the galaxy. Our results suggest that compact cores are formed through an extreme starburst due to a gravitational instability, triggered by non-corotating clumps.

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