Nanodiamond Promotes Surfactant-Mediated Triglyceride Removal from a Hydrophobic Surface at or below Room Temperature

We demonstrate that ca. 5 nm nanodiamond particles dramatically improve triglyceride lipid removal from a hydrophobic surface at room temperature using either anionic or nonionic surfactants. We prepare nanodiamond–surfactant colloids, measure their stability by dynamic light scattering and use quartz crystal microbalance–dissipation, a technique sensitive to surface mass, in order to compare their ability to remove surface–bound model triglyceride lipid with ionic and nonionic aqueous surfactants at 15–25 °C. Oxidized, reduced, ω-alkylcarboxylic acid, and ω-alkylamidoamine surface-modified adducts are prepared, and then characterized by techniques including ¹³C cross-polarization (CP) magic-angle spinning (MAS) NMR. Clear improvement in removal of triglyceride was observed in the presence of nanodiamond, even at 15 °C, both with nanodiamond–surfactant colloids, and by prior nanoparticle deposition on interfacial lipid, showing that nanodiamonds are playing a crucial role in the enhancement of the detergency process, providing unique leads in the development of new approaches to low-temperature cleaning

Three-Dimensional Hierarchical Structure ZnO@C@NiO on Carbon Cloth for Asymmetric Supercapacitor with Enhanced Cycle Stability

In this work, we synthesized the hierarchical ZnO@C@NiO core–shell nanorods arrays (CSNAs) grown on a carbon cloth (CC) conductive substrate by a three-step method involving hydrothermal and chemical bath methods. The morphology and chemical structure of the hybrid nanoarrays were characterized in detail. The combination and formation mechanism was proposed. The conducting carbon layer between ZnO and NiO layers can efficiently enhance the electric conductivity of the integrated electrodes, and also protect the corrosion of ZnO in an alkaline solution. Compared with ZnO@NiO nanorods arrays (NAs), the NiO in CC/ZnO@C@NiO electrodes, which possess a unique multilevel core–shell nanostructure exhibits a higher specific capacity (677 C/g at 1.43 A/g) and an enhanced cycling stability (capacity remain 71% after 5000 cycles), on account of the protection of carbon layer derived from glucose. Additionally, a flexible all-solid-state supercapacitor is readily constructed by coating the PVA/KOH gel electrolyte between the ZnO@C@NiO CSNAs and commercial graphene. The energy density of this all-solid-state device decreases from 35.7 to 16.0 Wh/kg as the power density increases from 380.9 to 2704.2 W/kg with an excellent cycling stability (87.5% of the initial capacitance after 10000 cycles). Thereby, the CC/ ZnO@C@NiO CSNAs of three-dimensional hierarchical structure is promising electrode materials for flexible all-solid-state supercapacitors

Antibacterial properties of polycrystalline diamond films

Electronic and mechanical properties, and their biocompatibility, make diamond-based materials promising biomedical applications. The cost required to produce high quality single crystalline diamond films is still a hurdle to prevent them from commercial applications, but the emergence of polycrystalline diamond (PCD) films grown by chemical vapour deposition (CVD) method has provided an affordable strategy. PCD films grown on silicon wafer have been used throughout and were fully characterised by SEM, XPS, Raman spectroscopy and FTIR. The samples contain nearly pure carbon, with impurities originated from the CVD growth and the silicon etching process. Raman spectroscopy revealed it contained tetrahedral amorphous carbon with small tensile stress. The sp2 carbon content, comprised between 16.1 and 18.8%, is attributed to the diamond grain boundaries and iron-catalysed graphitisation. Antibacterial properties of PCD films were performed with two model bacteria, i.e. Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) using direct contact and shaking flask methods. The samples showed strong bacteriostatic properties against S. aureus and E. coli with the direct contact method and no influence on planktonic bacterial growth. These results suggest that the bacteriostatic mechanism of PCD films is linked to their surface functional groups (carbon radicals and –NH2 and –COOH groups) and that no diffusible molecules or components were involved

Hierarchical NiO@NiCo₂O₄ Core–shell Nanosheet Arrays on Ni Foam for High-Performance Electrochemical Supercapacitors

A facile solvothermal method followed by a postannealing process is used to prepare NiO@NiCo₂O₄ core–shell nanosheet arrays supported on Ni foam substrate for a high-performance supercapacitor. The hybrid electrode possesses a three-dimensional structure with the “shell” of NiCo₂O₄ nanoflakes anchored on the “core” of ordered NiO nanosheets. It shows high specific capacitance of 1623.6 F g^–1 (or specific capacity of 225.5 mAh g^–1) at 2 A g^–1 and excellent rate performance with a 96% capacitance retention rate at 20 A g^–1. The high cycling stability is proved by nearly 90% capacitance retention at 10 A g^–1 after 10000 cycles. Its asymmetric supercapacitor, assembled with NiO@NiCo₂O₄/Ni foam and the activated carbon/Ni foam as the positive and negative electrode, respectively, displays the specific energy of 52.5 W h kg^–1 at 387.5 W kg^–1. The excellent electrochemical performance of NiO@NiCo₂O₄ electrode indicates its great potential in applications of energy storage devices

Doomed Couple of Diamond with Terahertz Frequency: Hyperfine Quality Discrimination and Complex Dielectric Responses of Diamond in the Terahertz Waveband

The technology age of terahertz (THz) frequency is coming with tremendous features and astonishing applications in various fields of science. Using THz time domain spectroscopy, we demonstrate experimentally, for the first time, the fingerprint absorption peaks and the complex dielectric response trends in 0.1-3 THz frequency waveband, on intentionally synthesized and processed chemical vapour deposition (CVD) polycrystalline and single-crystal diamond films with systematic quality-difference. The two absorption signatures within the 0.1-3 THz frequency band, in which the atomic vibration is materials-independent, are attributed to the sp2 phonon vibration modes of as-grown graphitic phases and/or defects. Regarding the complex dielectric responses of diamond in THz waveband, scattering effect resulting from the extended grain boundaries associated with concomitant pores (even gaps) (and/or extended crystal cleavage faults associated with amorphous carbon), as well as intrinsic lattice absorption resulting from increased sp2 impurities, have been taken into account. Especially the defect size comparable with the wavelength is also found to play a significant effect on the loss at higher-frequency electromagnetic wave. These findings are expected to promote not only ultra-sensitive quality diagnose for diamond but verification of an ideal transmission material for THz waveband applications

Smoothing of single crystal diamond by high-speed three-dimensional dynamic friction polishing: Optimization and surface bonds evolution mechanism

The high-speed three-dimensional movement dynamic friction polishing (3DM-DFP) has been recognized as an efficient approach for ultra-smoothing single crystal diamond (SCD) surface. Continuing from the previous works focusing on the subsurface cleavage of diamond after 3DM-DFP, process optimization and surface reaction evolution mechanism as a fundamental building block is investigated, for the first time, for comprehensively understanding this fast-smoothing manner. By systematically adjusting the controlling factor, stronger load (0.3 MPa) and appropriate duration (0.5 h) as well as moderate sliding speed (in the range of 30 to 45 m s−1) is found to be able to obtain the smooth surface of SCD without uncontacted traces or break-surface cleavage. Subtle residual clues on SCD surface as a function of progressive DFP procedure indicate that Fe catalytic oxidation mainly produce Fe2O3 and partial intermediate oxides Fe1-yO. Meanwhile, the activated oxygen inserts sp3 Csingle bondC bonds could form Csingle bondO or Cdouble bondO and C-O-V (vacancy) at existing reactive surface sites. The (100) favorable Cdouble bondO bonds can be rebuilt if (100) surface is reformed, although the Csingle bondO bonds associated with non-(100) rough surface would replace them during DFP procedure. The formed Csingle bondOsingle bondC and concomitant C-O-V as well as the oxidized graphite give rise to the increase of Csingle bondO proportion, and finally the covered defective graphitic phase has an approximate Csingle bondO/Cdouble bondO ratio of 1.25. All these are endowed potential value for future upgrading of DFP technique for diamond surface smoothing.</div