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A first composite material containing uniformly dispersed disaggregated detonation nanocrystalline diamonds (DNDs) in SiO2 aerogel matrix was prepared. The synthetic protocol included hydrolysis of tetramethyl orthosilicate (Si(OMe)4, TMOS) by hydrosol of surface carboxylated DNDs with a typical size of 4–5 nm with DMSO serving as a cosolvent and a stabilizer of DND single crystals. Composite samples containing DNDs in silica aerogel matrix in concentration 1.0, 0.1 and 0.01 % w/w were prepared at ambient temperature. HRTEM data revealed that DNDs nanocrystals were uniformly distributed in aerogel and did not form aggregates. Textural and optical composites' properties were determined. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) with nanocarbon fillers are at the high end of modern materials science, advancing current electronic applications. Herein, we establish the interplay between the chemistry and electrophysical properties of reduced graphene oxide (rGO), separately and as a filler for CPCs with the segregated structure conferred by the chemical composition of the initial graphene oxide (GO). A set of experimental methods, namely X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy, van der Paw and temperature-dependent sheet resistance measurements, along with dielectric spectroscopy, are employed to thoroughly examine the derived materials. The alterations in the composition of oxygen groups along with their beneficial effect on nitrogen doping upon GO reduction by hydrazine are tracked with the help of XPS. The slight defectiveness of the graphene network is found to boost the conductivity of the material due to facilitating the impact of the nitrogen lone-pair electrons in charge transport. In turn, a sharp drop in material conductivity is indicated upon further disruption of the π-conjugated network, predominantly governing the charge transport. Particularly, the transition from the Mott variable hopping transport mechanism to the Efros–Shklovsky one is signified. Finally, the impact of rGO chemistry and physics on the electrophysical properties of CPCs with the segregated structure is evaluated. Taken together, our results give a hint at how GO chemistry manifests the properties of rGO and the CPC derived from it, offering compelling opportunities for their practical applications. [ABSTRACT FROM AUTHOR]

The rational design of composites based on graphene/metal oxides is one of the pillars for advancing their application in various practical fields, particularly gas sensing. In this study, a uniform distribution of ZnO nanoparticles (NPs) through the graphene layer was achieved, taking advantage of amine functionalization. The beneficial effect of amine groups on the arrangement of ZnO NPs and the efficiency of their immobilization was revealed by core-level spectroscopy, pointing out strong ionic bonding between the aminated graphene (AmG) and ZnO. The stability of the resulting Am-ZnO nanocomposite was confirmed by demonstrating that its morphology remains unchanged even after prolonged heating up to 350 °C, as observed by electron microscopy. On-chip multisensor arrays composed of both AmG and Am-ZnO were fabricated and thoroughly tested, showing almost tenfold enhancement of the chemiresistive response upon decorating the AmG layer with ZnO nanoparticles, due to the formation of p-n heterojunctions. Operating at room temperature, the fabricated multisensor chips exhibited high robustness and a detection limit of 3.6 ppm and 5.1 ppm for ammonia and ethanol, respectively. Precise identification of the studied analytes was achieved by employing the pattern recognition technique based on linear discriminant analysis to process the acquired multisensor response. [ABSTRACT FROM AUTHOR]

According to the classical nucleation theory, the presence of solid particles in a liquid should facilitate its heterogeneous nucleation upon supercooling. Here, we have analysed the behaviour of aqueous dispersions of detonation diamond nanoparticles (DND) with different signs of the surface charge in supercooled conditions and the frozen state. The behaviours of the diamond nanoparticles with a typical size of 4.5 nm were compared with each other and with deionized water in ice nucleation and ice shear experiments. The presented experimental data and analysis allowed the description of the significant increase in the freezing delay times for positively charged nanoparticles and the sharp decrease for negatively charged ones in comparison to deionized water, based on the peculiarities of the water structure around the nanoparticles and in the vicinity of a superhydrophobic surface. In addition, this approach has allowed the successful explanation of the difference in the practical work of adhesion for deionized water and dispersions of DND with different particle charges. [ABSTRACT FROM AUTHOR]

The derivatization of graphene to engineer its band structure is a subject of significant attention nowadays, extending the frames of graphene material applications in the fields of catalysis, sensing, and energy harvesting. Yet, the accurate identification of a certain group and its effect on graphene's electronic structure is an intricate question. Herein, we propose the advanced fingerprinting of the epoxide and hydroxyl groups on the graphene layers via core-level methods and reveal the modification of their valence band (VB) upon the introduction of these oxygen functionalities. The distinctive contribution of epoxide and hydroxyl groups to the C 1s X-ray photoelectron spectra was indicated experimentally, allowing the quantitative characterization of each group, not just their sum. The appearance of a set of localized states in graphene's VB related to the molecular orbitals of the introduced functionalities was signified both experimentally and theoretically. Applying the density functional theory calculations, the impact of the localized states corresponding to the molecular orbitals of the hydroxyl and epoxide groups was decomposed. Altogether, these findings unveiled the particular contribution of the epoxide and hydroxyl groups to the core-level spectra and band structure of graphene derivatives, advancing graphene functionalization as a tool to engineer its physical properties. [ABSTRACT FROM AUTHOR]

This paper reports on the grafting of rare‐earth metal ions onto particles of 4–5 nm carboxylated detonation nanodiamond (DND‐COOH). Aqueous solutions of acetates and nitrates (Ln(OOCCH3)3·4H2O or Ln(NO3)3·6H2O, Ln = Eu, Gd) were used for the grafting. The ion exchange reaction between rare metal ions and protons of surface carboxyl groups was first detected by conductometry and electrokinetic potential measurements. The equivalence point corresponds to the bond between Ln3+ and the three carboxylate anions of DND‐COOH. Thus, we have demonstrated an easy synthetic approach for obtaining nanodiamond particles DND‐COOH with surface grafted with a controlled amount of any rare‐earth metal ions (DND‐COO‐ {Ln}, Ln = Ce, Pr, Sm, Eu, Gd, Dy, Ho, Tm). The resulting hybrid material DND‐COO‐{Eu} exhibits photoluminescence properties arising from f‐f transitions of Eu3+ ion. [ABSTRACT FROM AUTHOR]