АГ

А.В. Гаршев

Lomonosov Moscow State University

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ВА

В. А. Лебедев

Joint Institute for Nuclear Research

Anton S. Poluboyarinov

Lomonosov Moscow State University

Anna Yu. Romanchuk

Lomonosov Moscow State University

ВВ

В. В. Фадеев

Lomonosov Moscow State University

Ratibor G. Chumakov

Kurchatov Institute

E. A. Shirshin

Lomonosov Moscow State University

Evgeny Smirnov

ITMO University

Stepan N. Kalmykov

Lomonosov Moscow State University

Alexander Zherebker

Skolkovo Institute of Science and Technology

ГН

Г. Н. Мазо

St.Petersburg V.M.Bekhterev Psychoneurological Research Institute

Cooperative Institutions

Lomonosov Moscow State University

Moscow State University

NS Kurnakova Institute of General and Inorganic Chemistry

Russian Academy of Sciences

Kurchatov Institute

Institute of General and Inorganic Chemistry

Centre National de la Recherche Scientifique

Shenzhen MSU-BIT University

Frumkin Institute of Physical Chemistry and Electrochemistry

V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry

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Non-classical growth of water-redispersible spheroidal gold nanoparticles assisted by leonardite humate

CrystEngComm (2016)

Alexander Yu. Polyakov В. А. Лебедев Evgeny A. Shirshin Artem M. Rumyantsev Alexander B. Volikov

The growth of gold nanoparticles (AuNPs) assisted by humate – a natural hyperbranched polyelectrolyte – was studied using in situ and ex situ techniques. The conditions for formation of almost monodisperse gold nanospheres of 13 ± 3 nm diameter with pronounced plasmonic properties were defined. A striking similarity was found between humate- and citrate-mediated growth of AuNPs: the formation of gold nanospheres involved rapid nucleation of gold seeds, slow growth within the intermediate agglomerates (visible as nanoworms after drying on a TEM grid), and rapid peptization into the final gold nanospheres. Both humate and citrate syntheses produced ultrastable gold sols with pronounced plasmonic properties. The substantial difference was slower kinetics of humate synthesis, 240 min versus 15 min for citrate, and the water redispersible properties of the humate-capped gold nanospheres after freeze drying, which was not seen with the citrate AuNPs. Theoretical calculations revealed a leading role of steric factors in the formation of intermediate aggregates of capped AuNPs at the stage of their slow growth in the case of both citrate and humate. We suggested that it was the polyelectrolyte nature of humate which enabled the water-redispersibility of humate- versus citrate-capped gold nanoparticles.

Peptization

Dispersity

Agglomerate

10.1039/c6ce02149b

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Citations (14)

Synthesis and Decomposition of Nd_2–yCa_yCo_1–xNi_xO₄: The Effect of Resynthesis on the Catalytic Performance of Decomposition Products in the Partial Oxidation of Methane

ACS Applied Energy Materials (2021)

O.A. Shlyakhtin Sergey A. Malyshev А. С. Локтев Г. Н. Мазо А.В. Гаршев

In order to study the nanocomposite catalysts of the partial oxidation of methane (POM), a series of complex oxide precursors Nd2–yCayCo1–xNixO4 (y = 0.5–1; x = 0–1) were obtained by a freeze-drying synthesis method. It was found that the substitutions of Co with Ni and Ca with Nd in NdCaCoO4 could result in the formation of complex oxides with a K2NiF4 structure within the limited range of x and y. Distortions of the K2NiF4 structure caused by the complete substitution of Co with Ni promoted a change of space group from I4/mmm for NdCaCoO4 to Fmmm for Nd1.5Ca0.5NiO4. Analysis of the oxygen stoichiometry and valence states of transition metals revealed that Co(III) is substituted by the mixture of Ni(II) and Ni(III). The reduction of these complex oxides at 900 °C in hydrogen resulted in the formation of metal oxide nanocomposites consisted of 25–30 nm (Co,Ni) nanospheres at the surface of dense agglomerates of nanosized CaO and Nd2O3. All these composites demonstrated a significant catalytic activity in the POM reaction. The substitution of Co with Ni promoted the appearance of catalytic properties at lower temperatures up to T = 750 °C. The catalytic properties of Co-containing nanocomposites at T < 900 °C were severely affected by the resynthesis of NdCoO3 and Nd2–yCayCo1–xNixO4 in the POM environment. The formation of complex oxides from metal oxide nanocomposites occurred at reduced temperatures and caused a significant decrease of their particle size compared to traditional wet chemical synthesis methods.

Stoichiometry

10.1021/acsaem.1c00993

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Citations (6)

Am(III) sorption onto TiO2 samples with different crystallinity and varying pore size distributions

Applied Geochemistry (2014)

Nadezda Gracheva Anna Yu. Romanchuk Evgeny Smirnov Maria Meledina А.В. Гаршев

10.1016/j.apgeochem.2014.01.006

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Citations (19)

Non-classical growth of brookite nanorods

CrystEngComm (2019)

I. V. Kolesnik D. A. Kozlov Anton S. Poluboyarinov А.В. Гаршев В. К. Иванов

Under hydrothermal conditions, the formation of the brookite phase occurs due to the oriented attachment of anatase particles with subsequent recrystallization.

Nanorod

Brookite

10.1039/c9ce00682f

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Citations (9)