The ability of hydrogenated detonation nanodiamond particles to participate in CO2 reduction reactions producing formate and acetate ions on their surface was demonstrated. The reactions proceed in air and CO2 under normal conditions and do not require light, thermal and electrochemical activation. The products of CO2 reduction reactions were analyzed using IR spectroscopy and mass spectrometry. Deuterated acetate ions were synthesized by reducing CO2 in heavy water vapor to confirm the reaction. The issue of surface state of the detonation nanodiamond particles is also considered. The discovered enormous basicity of the hydrogenated particles indicates a high concentration of surface nitrogen in the amine configurations. All of this makes the hydrogenated detonation nanodiamond a promising material for production of multi-carbon compounds by CO2 reduction.

This study is devoted to clarifying the crystal structure of diamond particles synthesized by shock wave compression of graphite. Employing a comprehensive suite of methods—including energy dispersive X-ray spectroscopy, XRD, TEM and SEM, laser diffraction, DLS, Raman spectroscopy, nitrogen adsorption-desorption analysis, and SAXS—the research determines the particle size distributions, elucidates the nanocrystalline structure of the diamond particles, and characterizes their impurity compositions. The findings demonstrate that the intrinsic structural differences between diamond produced by detonation of explosives and those obtained through shock wave compression of graphite lead to a significantly lower efficiency of thermal disaggregation for the latter particles. Moreover, inclusions of hexagonal diamond (2H), also known as lonsdaleite, were observed within the crystal structure of the studied particles.

The paper is devoted to basic properties study of hydrogenated detonation nanodiamonds. It is shown that a powder of detonation nanodiamond annealed in molecular hydrogen contains carbonate and bicarbonate ions. These anions may be replaced for other anions during the interaction of the nanodiamond particles with aqueous solutions of salts and acids. The anion replacement is confirmed by Infrared and Energy dispersive X-ray spectroscopies. The presence of carbonate and bicarbonate ions indicates that the hydrogenated diamond nanoparticles have a positive surface charge in the powder according surface transport doping. Potentiometric titration and nitrogen adsorption methods have been used to calculate the surface charge of the particles.

We report on preparation, NMR and MRI study of suspensions of detonation nanodiamonds (DNDs) with manganese ions directly grafted to their surfaces, which are considered as novel contrast agents for MRI. We measured proton relaxation times, relaxivities and MRI images in aqueous and saline suspensions of manganese-grafted nanodiamonds, and those covered by polyvinylpyrrolidone, with different manganese concentrations. A comparison of the above parameters in Mn-grafted DNDs with those in the recently studied Gd-grafted DNDs and Dotarem, a contrast agent usually used in clinical practice, leads to a conclusion that Mn-grafted DNDs may serve as contrast agents for MRI.

The new applications of nanodiamond in biology and nuclear physics require the use of products with a low content of impurities.One of the possible methods for obtaining a high-purity nanodiamond is the recently developed laser synthesis method.The aim of this work was to study the state of aggregation of laser synthesis nanodiamond particles in aqueous suspensions and to test the possibility of deaggregation of laser nanodiamond.The process of deaggregation of a laser synthesis nanodiamond is investigated.It was shown that the previously described process of deaggregation by milling with baking soda and the usual process of deaggregation give almost the same results.A solid phase from a colloidal solution of a laser synthesis nanodiamond has been isolated and investigated.The low content of impurities in the studied product was confirmed (less than 0.1% at.), the Raman, IR, and EPR spectra were studied.

We report on a novel approach that allows determining the spatially resolved nuclear spin-lattice relaxation times and NMR line widths in nanomaterials. The approach was applied to a newly synthesized nanomaterial-detonation nanodiamonds with manganese ions directly grafted to the surface of the nanodiamond particles. The interaction of the carbon nuclear spins with paramagnetic Mn2+ ions results in acceleration of nuclear spin-lattice relaxation and broadening of the C-13 resonance line. Using spin dephasing experiments, we were able to determine the layer-by-layer contributions of the paramagnetic Mn2+ ions to the spin-lattice relaxation time and line width of the carbon spins positioned at different depths from the diamond surface. Developed for nanodiamonds, this approach is more general and can be successfully applied to study the distribution of nuclear relaxation rates and line broadening and for mapping magnetic interactions inside various nanoparticles, being of practical use in various nanotechnologies.

Aiming to develop versatile MRI contrast agents, we report on preparation and magnetic resonance study of a novel nanomaterial - detonation nanodiamond (DND) with manganese ions directly grafted to its surface. The sample was prepared by reacting an aqueous nanodiamond suspension with an aqueous solution of manganese sulfate. We present clear evidence on chemical binding of Mn2+ ions to nanodiamond surface; ions interact with electron and nuclear spins of a diamond nanoparticle, thus accelerating spin-lattice relaxation. The distance between Mn2+ ion and diamond surface was estimated from the 13C NMR relaxation data. Comparison of the interaction of Mn ions with DND to that in the recently studied Gd-grafted DND suggests that Mn-DND will be a potential material as an MRI contrast agent.

One of the industrially scalable methods for the synthesis of diamond crystals is shock compression of graphite. The method includes shock compression of graphite with explosives (RDX). Typical sizes of polycrystalline diamond particles produced by the method are in the range from 50 nm to 2 mu m. We submit a method for deagglomeration of that diamond particles and production of stable hydrosol of monodisperse particles with positive electrokinetic potential. The mean size of isolated diamond particles in the hydrosol is 4 nm. The method includes chemical purification of the commercial diamond powder, annealing of purified powder in hydrogen, and followed centrifugation.

Over a decade ago, it was confirmed that detonation nanodiamond (DND) powders reflect very cold neutrons (VCNs) diffusively at any incidence angle and that they reflect cold neutrons quasi-specularly at small incidence angles. In the present publication, we report the results of a study on the effect of particle sizes on the overall efficiency of neutron reflectors made of DNDs. To perform this study, we separated, by centrifugation, the fraction of finer DND nanoparticles (which are referred to as S-DNDs here) from a broad initial size distribution and experimentally and theoretically compared the performance of such a neutron reflector with that from deagglomerated fluorinated DNDs (DF-DNDs). Typical commercially available DNDs with the size of ~4.3 nm are close to the optimum for VCNs with a typical velocity of ~50 m/s, while smaller and larger DNDs are more efficient for faster and slower VCN velocities, respectively. Simulations show that, for a realistic reflector geometry, the replacement of DF-DNDs (a reflector with the best achieved performance) by S-DNDs (with smaller size DNDs) increases the neutron albedo in the velocity range above ~60 m/s. This increase in the albedo results in an increase in the density of faster VCNs in such a reflector cavity of up to ~25% as well as an increase in the upper boundary of the velocities of efficient VCN reflection.

Neutrons can be an instrument or an object in many fields of research. Major efforts all over the world are devoted to improving the intensity of neutron sources and the efficiency of neutron delivery for experimental installations. In this context, neutron reflectors play a key role because they allow significant improvement of both economy and efficiency. For slow neutrons, Detonation NanoDiamond (DND) powders provide exceptionally good reflecting performance due to the combination of enhanced coherent scattering and low neutron absorption. The enhancement is at maximum when the nanoparticle diameter is close to the neutron wavelength. Therefore, the mean nanoparticle diameter and the diameter distribution are important. In addition, DNDs show clustering, which increases their effective diameters. Here, we report on how breaking agglomerates affects clustering of DNDs and the overall reflector performance. We characterize DNDs using small-angle neutron scattering, X-ray diffraction, scanning and transmission electron microscopy, neutron activation analysis, dynamical light scattering, infra-red light spectroscopy, and others. Based on the results of these tests, we discuss the calculated size distribution of DNDs, the absolute cross-section of neutron scattering, the neutron albedo, and the neutron intensity gain for neutron traps with DND walls.

The structure of detonation nanodiamond clusters formed by grafting of metal ions was studied by small-angle neutron scattering. Detonation nanodiamond particles grafted by Eu atoms are located closer to each other and pack more regularly.

A new mechanism of heat transfer in nanofluids is proposed on the basis of two physical principles: Brownian motion of particles in a fluid and thermal resistance of a particle—fluid interface. Owing to the thermal resistance of interfaces, the temperature of particles may differ from the temperature of the surrounding fluid; i.e., the particles may be superheated or supercooled. The diffusion of superheated or supercooled particles makes an additional contribution to the heat flux. It turns out that this contribution is negligible for the fluid with the inclusion of nanoparticles. At the same time, the contribution to the heat transfer by this mechanism is large and may be dominant for a gas with the inclusion of nanoparticles.

This paper reports the results of the comparative structural characterization of detonation nanodiamond particles and their aggregates in hydrosols and hydrogels by small-angle scattering (SAS) techniques. The data from different neutron and X-ray (synchrotron radiation) diffractometers cover a wide range of momentum transfer and show multilevel structure organizations at the size scale from 1 to 1000 nm and higher. For this purpose, in addition to the conventional SAS techniques the methods of very small-angle and ultrasmall-angle neutron scattering were applied. The fraction of nanodiamond particles in the aggregates is determined. A complex two-step mechanism of nanodiamond cluster association into a network during the sol–gel transition is revealed. It is assumed that a reason for the reversibility of this process is a different compactness of the corresponding structural levels defined by different fractal organizations.

The use of modified detonation nanodiamonds in the most common gold-plating electrolytes—citrate and phosphate—makes it possible to increase microhardness by a factor of about 1.2 and wear resistance from 3.6 times up to that of a practically non-abradable coating, while keeping unchanged the electrolyte formulations, temperature, and current density which are typically used in the conventional technological process. The coating thickness is recommended to be reduced 2- to 3-fold.

The work presents the results of studying the structure of binary liquid nanocarbon systems obtained by mixing hydrosol of detonation nanodiamond and aqueous dispersions of single layer graphene oxide flakes. We studied size and space distribution of nanocarbon clusters formed upon interaction of the components in aqueous media by mutually complement methods of small-angle X-ray and neutron scattering. The formation of small secondary agglomerates of nanodiamond particles on the surface of graphene oxide flakes was concluded and supported by the data of transmission electron microscopy from dried samples. The observed effect can significantly modify the structure of nanocarbon composites formed of nanodiamond and graphene oxide. The structural features of binary dispersions detonation nanodiamond–graphene oxide should be taken into account at the preparation of the conductive composites of reduced graphene oxide for energy storage systems.

The structure of detonation nanodiamond aqueous dispersions grafted by europium or gadolinium atoms was investigated by small-angle neutron scattering over a wide size scale from 1 to 3000 nm. Similar to the previous studies of nanodiamond suspensions, a strong association of the particle into developed aggregates was revealed. While the characteristic aggregate size depends on the modification of the dispersions and varies in a wide interval of 35-1500 nm, the fractal character of clusters of nanodiamond particles (packed in a specialized branched form with a fractal dimension of 2.4) remains unchanged independent of the cluster size. The effect of the aggregate size increase upon grafting is considered as a basis for the stability reduction mechanism at the microstructural level.

We report on the first H-1 NMR relaxation and magnetic resonance imaging (MRI) study of aqueous suspensions of detonation nanodiamond (DND) grafted by Gd(III) ions. In contrast to Gd(III)-ND conjugates implemented via organic species, Gd(III) ions were directly grafted to the surface of DND particles. Such Gd(III)-grafted DND particles significantly shorten spin-lattice (T-1) and spin-spin (T-2) relaxation times of water protons providing relaxivities of r(1) = 33.4 and r(2) = 332 mM(-1) s(-1), which considerably exceed most of those reported in the literature. It makes the Gd(III)-grafted DND complexes attractive for use as novel MM contrast agents.

A simple method of stabilization of detonation nanodiamonds in isotonic aqueous-saline media was found, being a solution of an actual task for biomedical applications. The stable colloid of detonation nanodiamond particles with negative zeta-potential in isotonic medium can be produced by complexes formation with poly(vinylpyrrolidone). The mean size of the complexes is 30-35 nm. The stability conditions of the complexes were defined and their structure was determined by small-angle neutron scattering. The obtained hydrosols of nanodiamond particles are stable in physiological medium and can be used in biological researches and in medicine as drug carriers.