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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]

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.

The efficacy of oxygen (O) surface terminations on diamond is an important factor for the performance and stability for diamond-based quantum sensors and electronics. Given the wide breadth of O-termination techniques, it can be difficult to discern which method would yield the highest and most consistent O coverage. Furthermore, the interpretation of surface characterization techniques is complicated by surface morphology and purity, which if not accounted for will yield inconsistent determination of the oxygen coverage. We present a comprehensive approach to consistently prepare and analyze oxygen termination of surfaces on (100) single-crystalline diamond. We report on x-ray photoelectron spectroscopy (XPS) characterization of diamond surfaces treated with six oxidation methods that include various wet chemical oxidation techniques, photochemical oxidation with UV illumination, and steam oxidation using atomic layer deposition (ALD). Our analysis entails a rigorous XPS peak-fitting procedure for measuring the functionalization of O-terminated diamond. The findings herein have provided molecular-level insights on oxidized surfaces in (100) diamond, including the demonstration of clear correlation between the measured oxygen atomic percentage and the presence of molecular contaminants containing nitrogen, silicon, and sulfur. We also provide a comparison of the sp ^2 carbon content with the O1s atomic percentage and discern a correlation with the diamond samples treated with dry oxidation which eventually tapers off at a max O1s atomic percentage value of 7.09 ± 0.40%. Given these results, we conclude that the dry oxidation methods yield some of the highest oxygen amounts, with the ALD water vapor technique proving to be the cleanest technique out of all the oxidation methods explored in this work.

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]

The role and bonding arrangement of deliberately added sp2 carbon in maximising the current efficiency, output and longevity of boron doped diamond (BDD) electrodes for electrochemical dissolved ozone generation is elucidated. We show, using a zero-gap cell (ZGC) arrangement, how systematically increasing sp2 carbon results in increased ozone concentration and current efficiency. sp2 carbon addition is made using nanosecond pulse laser micromachining which converts BDD to sp2 carbon. Two ZGC geometries are investigated which both incorporate a Nafion membrane sandwiched between two BDD electrodes. Through-holes (perforations) are integrated into either the membrane or the BDD, the latter using laser micromachining which also converts the hole walls to sp2 carbon. Increasing the number of through-holes (or changing hole geometry), in the perforated BDD, increases the sp2 carbon content of the electrode (from 5 to 100 %). For the perforated Nafion membrane in contact with a planar BDD electrode, patterned laser micromachining of the BDD surface is used to control the sp2 carbon content of the electrode (from 4 to 100 %). For both electrodes, sp2 carbon content is significantly higher than is possible using diamond growth. sp2 carbon contents >40 % and >60 % for the planar and perforated BDD electrodes, respectively, are found to be particularly effective, allowing electrode designs to be proposed for optimised ZGC ozone generation. Notably, the sp2 carbon introduced via laser micromachining is shown to be extremely stable over 20 h (anode potential ∼ 10 V) in contrast to glassy carbon, which corrodes within 10 min. Whilst both are 100 % sp2 carbon, the laser-machined surface (after ozonolysis) is amorphous whereas the glassy carbon contains disorganized graphitic layers. This work also highlights the intriguing stability of amorphous sp2 carbon towards high oxidative potentials. [Display omitted] • Laser micromachining converts BDD to graphite coated with amorphous sp2 carbon. • The sp2 carbon content of BDD electrodes can be controlled from 4 to 100 %. • High levels of sp2 carbon in BDD enhance electrochemical ozone production (EOP). • New zero gap EOP cells are designed using perforated Nafion membranes. • During EOP, graphite converts fully to EOP stable amorphous sp2 carbon. [ABSTRACT FROM AUTHOR]

Boron-doped diamond (BDD) is of increasing interest for applications in electrochemical sensing. It is well known that the sp2 carbon content in BDD influences its electrochemical properties as electrode material. In this work, evidence is provided that the surface sp2 carbon content plays a crucial role in the electrochemical sensitivity of BDD towards glucose. Single-crystal BDD, freestanding polycrystalline BDD and glassy carbon (sp2 carbon reference material) were examined by voltammetry. Neither single-crystal BDD, which is free of sp2 carbon, nor pure sp2 glassy carbon could detect glucose in the range of 0.2–1.0 V. On the other hand, glucose oxidation was observed on polycrystalline BDD, and with increasing intensity with increase of sp2 carbon content. Thus, an optimum amount of (B-doped) sp2 carbon in the BDD electrode is needed for best sensing performance. Understanding this, and being able to control the composition of BDD, are not only important to glucose detection but to any electrochemical sensing application involving BDD.

Amorphous carbon (a-C) thin films have various useful properties; thus, their applications are wide-ranging. These properties are characterized by the ratio of sp3 to sp2 carbon in the thin film, and many studies have been reported on changing this ratio. In this paper, we used an F 2 laser with a wavelength of 157 nm to photoexcite the surface of an a-C thin film, and simultaneously photodecompose atmospheric oxygen molecules O 2 into excited singlet oxygen atoms O(1D). The results showed that O(1D) atoms can photochemically etch sp2 carbon in thin films significantly better than triplet oxygen atoms O(3P). Thus, we found that the surface layer of the a-C thin film was photochemically modified to be transparent. Raman spectroscopy revealed no change in the chemical bonding state of the transparently modified a-C thin film. On the other hand, in X-ray photoelectron spectroscopy, the intensity of the C 1s peak originated to sp2 carbon decreased. The refractive index was also slightly lowered, probably due to lowering film density. In addition, droplets mainly composed of sp2 carbon generated during thin film deposition were significantly removed after F 2 laser irradiation. The electrical resistivity slightly decreased upon F 2 laser irradiation and remarkably decreased as the substrate was heated, exhibiting low bandgap properties. Therefore, we succeeded in discovering a new method for changing the ratio of sp3 to sp2 carbon in a-C to be transparent thin film by preferentially generating O(1D) atoms using the F 2 laser, as a new elemental technology for fabricating transparent flexible electronic devices. [Display omitted] • Creating distinct atmosphere differences for O(1D) or O(3P) atoms by F 2 or ArF laser. • Effectiveness of O(1D) atoms in photochemical etching of sp2 carbon in a-C thin film. • Modification of a-C thin film to transparency only in case of F 2 laser irradiation. • Lowering refractive index of a-C thin film by F 2 laser due to lowering film density. • Low bandgap properties of transparently modified a-C thin film. [ABSTRACT FROM AUTHOR]

In this paper, we present a detailed report on Raman spectroscopic analysis of activated carbon (AC) samples obtained from two different biomass sources, namely, bamboo and coconut shell. The detailed analysis revealed that the local structure of the precursors was affected differently by the physical and chemical treatments prior to the preparation of AC. This leads to different structural features of the derived AC samples though processed under similar conditions. The influence of preparation methods and temperature on modifications in the D-, G-, and 2D-peak parameters of bamboo and coconut shell based AC (BAC and CSAC) such as peak positions, peak widths and peak intensity ratio were thoroughly described. We experimentally validate the stage-two of the three-stage Ferrari-Robertson phenomenological model of amorphous carbon for these biomass derived AC. We also show that the observed anomalies in the peak parameters are consistent with the stage-two process combined with the networking properties of biomass derived AC. Physically activated BAC and chemically activated CSAC prepared at a temperature of 600 °C showed greater disorder (I D /I G) values of 1.37 and 1.22 in their AC structures, respectively. Further analysis of 2D-peak indicated the greater turbostratic disorder (quasi 2D-continuous random network) in BAC compared to CSAC. [Display omitted] • Activated carbon is obtained from biomass precursors (coconut shell and bamboo). • Structural properties were accounted using Raman spectroscopy technique. • Local structure of precursors was affected differently by physical and chemical preparation methods. • Activated carbon's networking properties can explain anomalies in Raman peak parameters. • Prepared activated carbon exhibits turbostratic disorder, resembling a quasi-two-dimensional continuous random network. [ABSTRACT FROM AUTHOR]

The effect of sp2 carbon within a boron-doped diamond (BDD) electrode on the electrochemical reduction of CO2 is investigated for the first time. With increasing sp2 content, the Faradaic efficiency for the production of hydrogen (H2) under constant current density increases while that for the production of formic acid (HCOOH) decreases. Moreover, favorable electrolysis conditions for producing HCOOH shift in the negative potential direction with increasing sp2 content. This phenomenon is ascribed to the presence of adsorption sites on the sp2 carbon. This work provides guidance for selectively controlling the reduction of CO2 by adjusting the distribution of carbonaceous species in the BDD electrode.

Hydrogenated amorphous silicon carbide (a-SiC x :H) films have been deposited by plasma enhanced chemical vapor deposition (PECVD) system with different radio-frequency (RF) powers. The microstructure and optical properties of the films deposited at different RF powers have been studied. The results show that the sp2/sp3 ratio and the average size of sp2-C rich domains increase while the hydrogen content and the density of sp2-C rich domains in the film decreases with increasing RF power. In addition, the sp2 carbon domains are observed by HR-TEM, and a possible photoluminescence (PL) mechanism is also suggested: the strong PL emission originates from radiative recombination of excitons within sp2-C rich domains and C Si/C C random network. As RF power increases, the change of the PL properties can be attributed to the influence of RF power on the sp2-C rich domains and the C Si/C C random network. The corresponding color coordinates of PL spectra also show that the film has great application potential in white light emission. [ABSTRACT FROM AUTHOR]

The formation of sp2 carbon by the Boudouard reaction significantly damages the refractory ceramics. Sulphur is an efficient way to prevent the carbon deposition catalysed by Fe 3 C, in the presence of H 2. Thermogravimetric analysis was carried out on Fe 2 O 3 samples exposed to a CO/H 2 gas mixture at 600 °C. Solid sulphur was mixed with Fe 2 O 3 powder or continually added in the form of gas into the CO/H 2 reducing gas. The samples were characterised by X-ray diffraction, Raman spectroscopy, SEM and TEM. The addition of 100 ppm of sulphur species in the gas prevents the formation of carbon. The mechanism that governs the inhibition of the reaction is proposed, in which the formation of a thin protective FeS layer (0.5–1 nm) is involved. This study paves the way to an effective solution to inhibit the sp2 carbon deposition in the refractories by poisoning the Fe 3 C catalyst with sulphur. [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]

A thorough study on sp3 to sp2 carbon conversion in undoped and boron-doped diamond (BDD) thin (≈ 500 nm) layers leading to the desired sp2/sp3 carbon ratio and lateral distribution, which utilizes boron atom incorporation and infrared (IR) material laser processing has been performed. Polycrystalline as-grown (AG) or chem-mechanically polished (CMP) undoped diamond/BDD layers were investigated with respect to boron content and laser wavelength (800, 1030 nm). Boron incorporation leads to an increase in IR optical absorption and reduction of required energy fluence (F th ≈ 1 J cm−2) needed for sp3 to sp2 carbon conversion. Raman spectroscopy was performed to identify carbon conversion stages and to tailor the ideal parameters for other IR laser sources and required sp2/sp3 carbon ratio. Electrochemical parameters (Δ E p and I Ap / I Cp ratio) were obtained from cyclic voltammetry measurements of outer-([Ru(NH 3) 6 ]3＋/2＋) and inner-([Fe(CN) 6 ]3−/4−) sphere redox markers. Values of Δ E p and I Ap / I Cp are mainly influenced after conversion of 10% of sp3 to sp2 carbon. This trend is most pronounced for the [Fe(CN) 6 ]3−/4− redox marker, by decrease or increase of these parameters on AG or CMP BDD electrodes respectively. Electrochemical findings were supported by electrochemical impedance spectroscopy where R ct keeps the same trend as Δ E p values and double layer capacitance profoundly increases between 10 and 25% of surface conversion. [Display omitted] • IR laser processing of boron-doped diamond films enhances elchem performance. • Controlling sp2 carbon distribution over laser-processed surface. • Desired spot shaping with sp2 carbon at low laser fluence regime. • Electroactivity of sp2 carbon area confirmed on as-grown "undoped" BDD. • When sp2 carbon area < 25%, sp3 carbon phase dominates electrochemical activity. [ABSTRACT FROM AUTHOR]

Abstract: A highly crystalline LiFePO4/C phase was successfully synthesized by a microwave irradiation method in 4 min. SEM and particle size analysis indicate that the particle size of resulting LiFePO4/C is much smaller than that of the solid-state derived sample and that it mostly distributes in the range of 160–600 nm. Cycling tests show that the sample prepared by microwave method can deliver 150 mAh g−1 at 17 mA g−1(0.1C). Further AC impedance measurements reveal that the LiFePO4 electrode can be well activated after the first cycle as reflected by the dramatic decrease in the charge transfer resistance. [Copyright &y& Elsevier]

[Display omitted] • BDD electrodes with controlled amounts of sp2 carbon were systematically studied. • Glucose oxidation on BDD is strongly affected by the surface sp2 carbon content. • Single-crystal BDD is catalytically inert towards glucose oxidation. • Nucleation side of freestanding BDD showed highest sensitivity (7.25 µA mM−1 cm−2). • Optimum amount of sp2 carbon in BDD is needed for best sensing performance. Boron-doped diamond (BDD) is of increasing interest for applications in electrochemical sensing. It is well known that the sp2 carbon content in BDD influences its electrochemical properties as electrode material. In this work, evidence is provided that the surface sp2 carbon content plays a crucial role in the electrochemical sensitivity of BDD towards glucose. Single-crystal BDD, freestanding polycrystalline BDD and glassy carbon (sp2 carbon reference material) were examined by voltammetry. Neither single-crystal BDD, which is free of sp2 carbon, nor pure sp2 glassy carbon could detect glucose in the range of 0.2–1.0 V. On the other hand, glucose oxidation was observed on polycrystalline BDD, and with increasing intensity with increase of sp2 carbon content. Thus, an optimum amount of (B-doped) sp2 carbon in the BDD electrode is needed for best sensing performance. Understanding this, and being able to control the composition of BDD, are not only important to glucose detection but to any electrochemical sensing application involving BDD. [ABSTRACT FROM AUTHOR]

• Electrochemical reduction of CO 2 was conducted on BDD electrodes with differing sp2 content. • With increasing sp2 content, the production of formic acid was reduced. • Onset potential of CO 2 RR shifted to more negative value on increasing sp2. • The adsorption site on sp2 carbon is important for CO 2 RR. • Selectivity of CO 2 RR can be controlled by adjusting carbonaceous species in BDD electrode. The effect of sp2 carbon within a boron-doped diamond (BDD) electrode on the electrochemical reduction of CO 2 is investigated for the first time. With increasing sp2 content, the Faradaic efficiency for the production of hydrogen (H 2) under constant current density increases while that for the production of formic acid (HCOOH) decreases. Moreover, favorable electrolysis conditions for producing HCOOH shift in the negative potential direction with increasing sp2 content. This phenomenon is ascribed to the presence of adsorption sites on the sp2 carbon. This work provides guidance for selectively controlling the reduction of CO 2 by adjusting the distribution of carbonaceous species in the BDD electrode. [ABSTRACT FROM AUTHOR]

N-doped carbon materials represent a type of metal-free catalyst for diverse organic synthetic reactions. However, single N-doped carbon materials perform insufficiently in the selective oxidation reaction of C-H bond compared with metal catalysts or multielement co-doped materials. There are a few reports on the application of three-dimensional (3D) carbon materials in such a reaction. Besides, the relationship between the well-developed porous structures, heteroatom doping, and their catalytic performance is unclear. In this study, 3D porous N-doped graphene aerogel catalysts with high activity and selectivity for the C-H bond oxidation under mild reaction conditions have been synthesized through a two-step method. Systematic studies on the dosage of N sources, pyrolysis temperature, and their influences on the catalytic performances have been evolved. Moreover, solid evidence of the synergistic effect of sp 2 C atoms adjacent to the N atoms and porous structure promoting the performance has been provided in this work.

A hybrid sp 2 -sp 3 electrochemical sensor comprising patterned regions of nondiamond-carbon (sp 2 ) in a boron doped diamond (sp 3 ) matrix is described for the simultaneous voltammetric detection of dissolved oxygen (DO) and pH in buffered aqueous solutions. Using a laser micropatterning process it is possible to write mechanically robust regions of sp 2 carbon into a BDD electrode. These regions both promote the electrocatalytic reduction of oxygen and facilitate the proton coupled electron transfer of quinone groups, integrated into the surface of the sp 2 carbon. In this way, in one voltammetric sweep (time of measurement ∼4 s) it is possible to determine both the DO concentration and solution pH. By varying the sp 2 pattern the response can be optimized toward both analytes. Using a closely spaced sp 2 microspot array, a linear response toward DO, across the range 0.0 to 8.0 mg L -1 (0.0 to 0.25 mM; sensitivity = -8.77 × 10 -8 A L mg -1 , R 2 = 0.9991) and pH range 4-10 (sensitivity = 59.7 mV pH -1 , R 2 = 0.9983) is demonstrated. The electrode is also capable of measuring both DO concentration and pH in the more complex buffered environment of blood. Finally, we show how the peak position for ORR is independent of pH, and thus via measurement of the difference in ORR and pH peak position, internal referencing is possible. Such electrodes show great promise for use in applications ranging from biomedical sensing to water analysis.

A two-dimensional (2D) sp 2 -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 sp 2 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., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Detonation nanodiamonds (DNDs) have unique physical and chemical properties that make them invaluable in many applications. However, DNDs are generally assumed to show weak fluorescence, if any, unless chemically modified with organic molecules. We demonstrate that detonation nanodiamonds exhibit significant and excitation-wavelength-dependent fluorescence from the visible to the near-infrared spectral region above 800 nm, even without the engraftment of organic molecules to their surfaces. We show that this fluorescence depends on the surface functionality of the DND particles. The investigated functionalized DNDs, produced from the same purified DND as well as the as-received polyfunctional starting material, are hydrogen, hydroxyl, carboxyl, ethylenediamine, and octadecylamine-terminated. All DNDs are investigated in solution and on a silicon wafer substrate and compared to fluorescent high-pressure high-temperature nanodiamonds. The brightest fluorescence is observed from octadecylamine-functionalized particles and is more than 100 times brighter than the least fluorescent particles, carboxylated DNDs. The majority of photons emitted by all particle types likely originates from non-diamond carbon. However, we locally find bright and photostable fluorescence from nitrogen-vacancy centers in diamond in hydrogenated, hydroxylated, and carboxylated detonation nanodiamonds. Our results contribute to understanding the effects of surface chemistry on the fluorescence of DNDs and enable the exploration of the fluorescent properties of DNDs for applications in theranostics as nontoxic fluorescent labels, sensors, nanoscale tracers, and many others where chemically stable and brightly fluorescent nanoparticles with tailorable surface chemistry are needed.