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This study introduces a novel magnetic nanohybrid material consisting of ferromagnetic (FM) bcc Fe–Co nanoparticles (NPs) grown on nanodiamond (ND) nanotemplates. A combination of wet chemistry, which produces chemical precursors and their subsequent thermal treatment under vacuum, was utilized for its development. The characterization and study of the prepared samples performed with a range of specialized experimental techniques reveal that thermal treatment of the as-prepared hybrid precursors under a range of annealing conditions leads to the development of Co-rich Fe–Co alloy NPs, with average sizes in the range of 6–10 nm, that exhibit uniform distribution on the surfaces of the ND nanotemplates and demonstrate FM behavior throughout a temperature range from 2 K to 400 K, with maximum magnetization values ranging between 18.9 and 21.1 emu/g and coercivities ranging between 112 and 881 Oe. Moreover, 57Fe Mössbauer spectroscopy reveals that apart from the predominant bcc FM Fe–Co phase, iron atoms also participate in the formation of a secondary martensitic-type Fe–Co phase. The emergence of this distinctive phase is attributed to the diffusion of carbon atoms within the Fe–Co lattices during their formation at elevated temperatures. The source of these carbon atoms is related to the unique morphological properties of the ND growth matrices, which facilitate surface sp2 formations. Apart from their diffusion within the Fe–Co NP lattice, the carbon atoms also reconstruct layered graphitic-type nanostructures enveloping the metallic alloy NPs. These non-typical nanohybrid materials, reported here for the first time in the literature, hold significant potential for use in applications related, but not limited to, biomedicine, biopharmaceutics, catalysis, and other various contemporary technological fields. [ABSTRACT FROM AUTHOR]

Carbon-based nanomaterials are viewed as preferred candidates as photothermal agents in tumor photothermal therapy due to their tailored structure and excellent biocompatibility. Herein, onion-like carbon (OLC) with controlled sp2/sp3-hybridized carbon ratios was explored as an effective photothermal reagent. The OLC was synthesized through thermal annealing of nanodiamonds, with an increase of the sp2 carbon content as the annealing temperature increased. The obtained OLC demonstrated high photothermal efficiency under 808 nm laser irradiation with a maximum value of 74.36% at an annealing temperature of 1400 °C. We suggest that a well-regulated amount of sp2 carbon in the OLC provided an abundance of conjugated π bonds, leading to enhanced light absorption and electron–phonon coupling. In addition, the OLC was conjugated with polyethylene glycol (PEG) and fluorescent molecules (FITC) to visualize the cellular uptake in HCT 116. In vivo tests demonstrated that the OLC-PEG-FITC exhibited good biocompatibility and achieved photothermal killing of cancer cells upon near-infrared laser irradiation. After treatment with the OLC-based photothermal agent, tumor tissues in tumor-bearing mice were effectively ablated. Taken together, these findings confirm the potential of the developed OLC as a photothermal agent for tumor therapy. [ABSTRACT FROM AUTHOR]

The bulk, pristine sp2 carbons, such as graphite, carbon nanotubes, and graphene, are usually assumed to be typical diamagnetic materials. However, over the past two decades, there have been many reports about the ferromagnetism in these sp2 carbon materials, which have attracted intense interest for basic research and potential applications. In this review, we focus on the evidence and developments of the emergent ferromagnetism in sp2 carbon revealed by nine kinds of experimental methods: magnetic force microscopy (MFM), magnetization measurements with physical property measurement system (PPMS), X-ray magnetic circular dichroism (XMCD), scanning tunneling microscopy (STM), miniaturized magnetic particle inspection (MPI), anomalous Hall effect (AHE), mechanical deflection of carbon nanotube cantilevers, magnetoresistance, and spin-related devices (spin field effect transistor and spin memory). The advantages, conclusions, challenges, and future of these methods are discussed. The ferromagnetism in sp2 carbon will open a door to explore exotic physical phenomena and lay the basis for the development of integrated circuit of spintronics, which is fundamentally different from charge-based conventional electronics. [ABSTRACT FROM AUTHOR]

Diamond is an important material for electrical and electronic devices. Because the diamond is in contact with the metal in these applications, it becomes necessary to study the metal–diamond interaction and the structure of the interface, in particular, at elevated temperatures. In this work, we study the interaction of the (100) and (111) surfaces of a synthetic diamond single crystal with spattered titanium and molybdenum films. Atomic force microscopy reveals a uniform coating of titanium and the formation of flattened molybdenum nanoparticles. A thin titanium film is completely oxidized upon contact with air and passes from the oxidized state to the carbide state upon annealing in an ultrahigh vacuum at 800 °C. Molybdenum interacts with the (111) diamond surface already at 500 °C, which leads to the carbidization of its nanoparticles and catalytic graphitization of the diamond surface. This process is much slower on the (100) diamond surface; sp2-hybridized carbon is formed on the diamond and the top of molybdenum carbide nanoparticles, only when the annealing temperature is raised to 800 °C. The conductivity of the resulting sample is improved when compared to the Ti-coated diamond substrates and the Mo-coated (111) substrate annealed at 800 °C. The presented results could be useful for the development of graphene-on-diamond electronics. [ABSTRACT FROM AUTHOR]

Amorphous carbon (AC) is present in the bulk and on the surface of nanostructured carbon materials (NCMs) and exerts a significant effect on the physical, chemical and mechanical properties of NCMs. Thus, the determination of AC in NCMs is extremely important for controlling the properties of a wide range of materials. In this work, a comparative study of the effect of heat treatment on the structure and content of amorphous carbon in deposited AC film, nanodiamonds, carbon black and multiwalled carbon nanotube samples was carried out by TEM, XPS, XRD and Raman spectroscopy. It has been established that the use of the 7-peak model for fitting the Raman spectra makes it possible not only to isolate the contribution of the modes of amorphous carbon but also to improve the accuracy of fitting the fundamental G and D2 (D) modes and obtain a satisfactory convergence between XPS and Raman spectroscopy. The use of this model for fitting the Raman spectra of deposited AC film, ND, CB and MWCNT films demonstrated its validity and effectiveness for investigating the amorphous carbon in various carbon systems and its applicability in comparative studies of other NCMs. [ABSTRACT FROM AUTHOR]

A two‐dimensional (2D) sp2‐carbon‐linked conjugated polymer framework (2D CCP‐HATN) has a nitrogen‐doped skeleton, a periodical dual‐pore structure and high chemical stability. The polymer backbone consists of hexaazatrinaphthalene (HATN) and cyanovinylene units linked entirely by carbon–carbon double bonds. Profiting from the shape‐persistent framework of 2D CCP‐HATN integrated with the electrochemical redox‐active HATN and the robust sp2 carbon‐carbon linkage, 2D CCP‐HATN hybridized with carbon nanotubes shows a high capacity of 116 mA h g−1, with high utilization of its redox‐active sites and superb cycling stability (91 % after 1000 cycles) and rate capability (82 %, 1.0 A g−1 vs. 0.1 A g−1) as an organic cathode material for lithium‐ion batteries. Doping for performance: A 2D sp2‐carbon‐linked conjugated polymer (2D CCP) framework with a nitrogen‐doped skeleton and multiple redox‐active sites consists of hexaazatrinaphthalene (HATN) and cyanovinylene units linked entirely by carbon–carbon double bonds. Hybridization with carbon nanotubes results in an excellent cathode material for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]