Carbon Films Research Articles

A hybrid SERS sensing platform constructed by porous carbon/Ag nanoparticles for efficient imatinib detection in bio-environment

Surface enhanced Raman scattering (SERS) is a rapid and non-destructive spectral detection technique, and has been widely implemented on trace-level molecule detection. In this work, a hybrid SERS substrate constructed by porous carbon film and silver nanoparticles (PCs/Ag NPs) was developed and then used for imatinib (IMT) detection in bio-environment. The PCs/Ag NPs was prepared by direct carbonizing the gelatin-AgNO3 film in the air atmosphere, and an enhancement factor (EF) of 106 was achieved with R6G as the Raman reporter. Hereafter, this SERS substrate was used as the label-free sensing platform to detect the IMT in the serum, and the experimental results indicate that the substrate is conducive to eliminating the interference from the complex biological molecules in the serum, and the characteristic Raman peaks belonging to IMT (10-4 M) are accurately resolved. Furthermore, the SERS substrate was used to trace the IMT in the whole blood, the trace of ultra-low concertation of IMT is rapidly discovered without any pretreatment. Thus, this work finally suggests that the proposed sensing platform provides a rapid and reliable method for IMT detection in the bio-environment and offers a potential for its application in therapeutic drug monitoring.

High-performance amorphous carbon films on titanium foils: Toward industrial preparation of coated metallic bipolar plates for proton exchange membrane fuel cells

The proton exchange membrane fuel cells (PEMFCs) composed of amorphous carbon (a-C) film surface modified metal bipolar plates (BPP) have been widely used as a new generation power source for hydrogen energy applications. However, one of the main challenges limiting the industrial deployment of a-C coated BPP remains the low deposition rate. In this study, arc ion plating with a deposition rate exceeding 100 nm/min was used to rapidly deposit a-C films with excellent performance on the surface of titanium foil (TA1). The experimental results show that the ICR of a-C coated TA1 decreases to 1.125 mΩ cm2 at a pressure of 1.4 MPa and the corrosion current density is about 3.37 × 10−9 A cm−2. In addition, industrially useable BPPs with large-sized coated a-C films has been successfully deposited. This work provides valuable reference for the industrial preparation of low-cost a-C film coating metal BPP for PEMFCs.

Diamond-like carbon (DLC)-coated titanium surface inhibits bacterial growth and modulates human alveolar bone cell responses in vitro

Modifying the titanium alloy (Ti-6Al-4V) surface plays a key role in improving biological responses. The present work aimed to determine the response of human alveolar bone cells to the diamond-like carbon (DLC) film and to evaluate the antibacterial effect of DLC-coated titanium. The alloys were deposited with different compositions, including C2H2 (DLC), carbon tetrafluoride (CF4:C2H2; F-DLC), and tetramethylsilane (Si(CH3)4:C2H2; Si-DLC). The surface morphology and wettability were measured using an atomic force microscopy (AFM) and a contact angle measurement. Titanium coated with DLC, F-DLC, or Si-DLC increased surface roughness and hydrophobicity. The ratio of spreading cells to initial rounded attaching cells at 20 min of all modified surfaces was higher than that of the control surfaces. F-DLC showed better cell spreading at 20 min compared to other conditions, as observed by scanning electron microscopy (SEM). The DLC, F-DLC, and Si-DLC coating significantly promoted cell proliferation compared to the Ti-6Al-4V control surfaces. ALP mRNA expression was significantly reduced on DLC surfaces compared to the control on day 14. Additionally, ALP and BMP2 mRNA expression increased on F-DLC-coated surfaces, but there were no statistically significant differences. However, DLC surfaces promoted higher mineral deposition than the control. The lower Staphylococcus aureus colony was observed on the surface of the DLC and F-DLC. In conclusion, the DLC-modified Ti-4Al-6V surface modulates cell attachment, proliferation, osteogenic marker gene expression, and bacterial growth. Herein, DLC-coated titanium alloys are still needed for continued development as an alternative biomaterial in dental applications.

Effects of intrinsic mechanical properties on the dynamic bonding strength of GLC films undergoing ball bearing contact fatigues

Wear-resistant films, which are widely applied to extend the service life of the gears and bearings, usually surfer from dynamic bonding fatigue failure induced by the Hertz-like contact. However, there is still lack of research on the influence of the main mechanical parameters of films on the dynamic bonding fatigue failure mechanism. In this work, graphite-like carbon (GLC) films with a low friction coefficient and different Ti doping ratios were deposited on the surface of stainless steel via direct current magnetron sputtering (DCMS) technology. The microstructure and mechanical properties of the films before and after vacuum annealing were investigated by SEM, Raman, and nanoindentation, and the dynamic bonding failure life of the films were evaluated by the ball-bearing-disc method with dynamic contact fatigue loads. The results revealed that the critical dynamic bonding strength exhibited a significant function dependence on the values of hardness-to-elastic modulus (H3/E2) parameters of the GLC films. The film failure mechanism showed a transition from the film/substrate interface spalling mode to the near-surface cohesion shear spalling mode with the increase of H3/E2.

Characteristics of Supercapacitor Electrodes Based on Doped Silicon Carbon Films

Characteristics of Supercapacitor Electrodes Based on Doped Silicon Carbon Films

Microstructure and electrothermal properties of carbon films derived from a sustainable organically-soluble wholly aromatic polyamide

Microstructure and electrothermal properties of carbon films derived from a sustainable organically-soluble wholly aromatic polyamide

Crystal structure of 9,10-bis-((perchloro-phenyl)-ethynyl)anthracene determined from three-dimensional electron diffraction data

Abstract The crystal structure of the title compound was determined using electron diffraction data collected in continuous rotation mode. The structure was successfully solved and refined kinematically in the monoclinic space group P21/c, with a Z value of 2 and Z′ value of 0.5. Within the crystal structure, the entire molecule is predominantly flat. The molecular packing exhibits a herringbone pattern, distinct from that of the unchlorinated analogue molecule. The largest facet of the crystals, which faces the supporting carbon film, is designated as (0 1 ‾ 1 ‾ $\bar{1}\bar{1}$ ).

Effects of Different Silicon Substrates on the Structure and Properties of Deposited Diamond‐like Carbon Films

Diamond‐like carbon (DLC) has attracted much attention due to its unique properties such as excellent physicochemical and biological properties. Herein, DLC coatings are deposited on four different silicon substrates using a radio frequency plasma‐assisted chemical vapor deposition (RF‐PECVD) technique. The structure and mechanical properties of DLC coatings deposited on different types of silicon substrates under different powers are compared. The surface morphology of the samples is characterized by scanning electron microscopy. The surface roughness of DLC films deposited on different silicon substrates is measured by scanning probe microscopy (SPM). The structural changes of the coatings are investigated by visible Raman spectroscopy. The analysis of DLC films deposited on different silicon substrates reveals that the structure of DLC films deposited on silicon is affected by different crystal directions of silicon substrates (different atomic densities in different crystal directions) and different conduction modes (electronic conduction and hole conduction). Regarding the DLC films deposited on the same substrate, the overall performance of P‐type silicon is better at 150 W, and the overall performance of N‐type silicon is better when the deposition power is 100 W.

Low-Strain KVPO4F@C as Hyperstable Anode for Potassium-Ion Batteries

Potassium-ion batteries with carbon-based materials and alloy materials as anodes possess pronounced potassium storage and cycling abilities, yet they suffer from harsh synthetic processes, low initial Coulombic efficiency, and limited structure stability. Herein, we first put forward potassium vanadium fluorophosphate (KVPO4F) as a highly stable anode material for potassium-ion batteries (PIBs). KVPO4F@C composite is successfully synthesized through hydrothermal method followed by a low-temperature roasting process. An amorphous carbon film is homogeneously wrapped on the surface of the KVPO4F particles to improve electronic conductivity. As the anode for PIBs, the KVPO4F@C presents a super-high discharge capacity of 242.32 mAh g−1 and a superior cycle stability over 120 cycles at 100 mA·g−1 with 93.1% capacity retention. Additionally, it maintains 92.9% of its initial capacity of 100 mA·g−1 at 1000 mA·g−1 after cycling 2100 times, which indicates an excellent long cycling performance. The in situ X-ray Diffraction and ex situ Transmission Electron Microscopy tests prove the minimal volume variation and stable structure of KVPO4F@C. The designed KVPO4F@C provides facilitative electronic conductivity and stable structure, successfully innovating an ultra-stable and high-performance anode material for potassium-ion batteries and other energy storage application fields.

Porous carbon nanofibres with humidity sensing potential

Based on polyacrylonitrile (PAN)/poly(vinylpyrrolidone) (PVP) electrospun precursor fibres, this work developed an efficient and cost-effective pore generation approach to produce porous carbon nanofibres (PCNFs) with humidity sensing potential. PAN/PVP fibres were treated by a blend of N,N-dimethylmethanamide (DMF) and water (H2O) to generate a highly porous structure. Through the collective effects of crystallisation of PAN and dissolution of PVP, the solid PAN/PVP fibres were transformed to be porous ones with higher surface areas. Carbon nanofibres (CNFs) and PCNFs were manufactured from untreated and treated PAN/PVP fibres following air stabilisation at 260 °C and argon carbonisation at 1000 °C. Surface area and pore volume are both increased on PCNFs. To obtain a flexible carbon film for humidity sensing, the cellulose fibres were then combined with PCNFs and CNFs. After characterising the sensing performance of composite films in dynamic and static situations, experimental results demonstrated the PCNFs film's promising future as a stable and reactive humidity sensor.

Biocompatibility of antifogging SiO-doped Diamond-Like carbon laparoscope coatings

Laparoscopes can suffer from fogging and contamination difficulties, resulting in a reduced field of view during surgery. A series of diamond-like carbon films, doped with SiO, were produced by pulsed laser deposition for evaluation as biocompatible, antifogging coatings. DLC films doped with SiO demonstrated hydrophilic properties with water contact angles under 40°. Samples subjected to plasma cleaning had improved contact angle results, with values under 5°. Doping the DLC films with SiO led to an average 40% decrease in modulus and 60% decrease in hardness. Hardness of the doped films, 12.0 – 13.2 GPa, was greater than that of the uncoated fused silica substrate, 9.2 GPa. The biocompatibility was assessed through CellTiter-Glo assays, with the films demonstrating statistically similar levels of cell viability when compared to the control media. The absence of ATP released by blood platelets in contact with the DLC coatings suggests in vivo hemocompatibility. The SiO doped films displayed improved transparency levels in comparison to undoped films, achieving up to an average of 80% transmission over the visible spectrum and an attenuation coefficient of 1.1 × 104 cm−1 at the 450 nm wavelength. The SiO doped DLC films show promise as a method of fog prevention for laparoscopes.

Relationship between Osteoblast Proliferation and the Surface Properties of Polymer-like Carbon Films Deposited at Different Ar/CH4 Mixed-Gas Ratios in the Radio-Frequency Plasma CVD Process

In the deposition of polymer-like carbon (PLC) films on Si substrates via radio-frequency plasma CVD (RF-PCVD), the effect of the Ar/CH4 gas mixture ratio on the bio-interface of the PLC films remains unclear and the effectiveness of introducing Ar gas must be proven. In this study, five types of PLC films are prepared on Si substrates via RF-PCVD with an Ar/CH4 gas mixture. The effects of the Ar/CH4 gas ratio on the structure, surface properties, and osteoblast proliferation of the PLC films are investigated. The PLC film structure is graphitized as the hydrogen content in the PLC film decreases with the increasing Ar gas ratio. Based on in vitro cell culture tests, a PLC film with a higher Ar gas ratio promotes the osteoblast proliferative potential after 72 h compared with a PLC film with a relatively low Ar gas ratio. Moreover, the surface roughness and hydrophilicity of the PLC film increase with the Ar gas ratio. Accordingly, we demonstrate the effectiveness of Ar gas incorporation into the RF-PCVD process to promote the biological responsiveness of PLC films. PLC coatings are expected to be widely applied for surface modification to improve the mechanical characteristics and biological responses of orthopedic implant devices.

Electrical Properties of Silicon Oxide Layers Subjected to High-Temperature Treatment Reproducing the Growth Conditions for Thin Carbon Films

Electrical Properties of Silicon Oxide Layers Subjected to High-Temperature Treatment Reproducing the Growth Conditions for Thin Carbon Films

A comparison between ion irradiation assisted- and electron irradiation assisted-oxygen plasma treatment on modification of nanostructured carbon films

Oxygen plasma treatment has been used for surface modification of carbon materials. However, the working mechanism is not well clarified. Here, the ion irradiation assisted- and electron irradiation assisted-oxygen plasma etching were proposed and realized in an electron cyclotron resonance plasma processing system. The effects of the ion assisted- and electron assisted-argon plasma and oxygen plasma etching on the surface morphology and nanostructure of graphene nanocrystallites embedded carbon film were compared. In the ion assisted plasma etching, compared with argon plasma, the oxygen introduction made the sp2/sp3 and ID/IG of the film upper layer further decrease. While in the electron assisted plasma etching, after O2 introduction, the sp2/sp3 and ID/IG in the film upper layer increased. Then the oxygen plasma treatment mechanism was proposed. In the ion assisted oxygen plasma treatment, the attracted oxygen positive ions took major effect, which would reduce the threshold energy for atom displacement and then implant more carbon or oxygen atoms into the film subsurface to make the film denser. In the electron assisted oxygen plasma treatment, the neutral oxygen took major effect, which would preferentially react with the more unstable amorphous carbon and then make the film equipped with more sp2 bonds.

Tannic Acid-Derived Carbon Coating on LiFePO4 Nanocrystals Enables High-Rate Cathode Materials for Lithium-Ion Batteries

Tannic acid (TA) is a plant polyphenol capable of coating hydrothermally grown LiFePO4 nanocrystals by simple wet impregnation and drying. Mild pyrolysis in an inert atmosphere transforms the TA coating on LiFePO4 nanocrystals into homogeneous and compact carbon films. Introducing conductive carbon films on LiFePO4 nanocrystals increases the electrical conductivity of the LiFePO4/C composite. However, reaction kinetics revealed that excessively thick carbon films limit the Li+ diffusivity of the LiFePO4/C composite during delithiation/lithiation. Therefore, the electrical conductivity and Li+ diffusivity must be balanced to achieve the required electrochemical properties.

Hydrogenated amorphous carbon films deposited using plasma enhanced chemical vapor deposition processes

Hydrogenated amorphous carbon films deposited using plasma enhanced chemical vapor deposition processes

Regulating the fretting behavior of diamond-like carbon films by changing the composition and structure

Reducing or eliminating the slip regime and mix regime is an effective way to reduce the fretting wear, while the diamond-like carbon (DLC) film, as a self-lubricating solid lubricant, can reduce friction coefficient while improving the surface strength. The most valuable thing is that DLC film can change the film's composition, structure, and physical and chemical properties by controlling its deposition process. This regularability can realize the reduction or elimination of slip regime and mix regime under different fretting conditions, so it is important to explore the changing regulation law of the fretting regime by changing the sp2/sp3 hybrid bond content ratio and microstructure of DLC film. Here, DLC films with different sp2/sp3 hybrid carbon content ratios were obtained by annealing; the fretting performance was studied under different normal loads and amplitudes. The following rules are obtained by drawing the running conditions fretting map and analyzing the tangential stiffness, friction coefficient and dissipation energy: with increasing the sp2/sp3 hybrid carbon content of DLC film, the fretting regime moves towards the slip regime, while the friction coefficient and dissipated energy will increase. In addition, the short-range ordered microstructure, such as onion-like carbon structure, will facilitate the fretting regime towards the partial slip regime. This work demonstrates the controllability and potential of DLC films in fretting.

Ag NC and Ag NP/PorC Film-Based Surface-Enhanced Raman Spectroscopy-Type Immunoassay for Ultrasensitive Prostate-Specific Antigen Detection.

Surface-enhanced Raman scattering (SERS) is a spectral detection technology with high sensitivity and detectivity and can be used to detect the fingerprint information of the molecules with ultralow concentration. Herein, a kind of immunostructure constructed by Ag nanoparticle/porous carbon (Ag NP/PorC) films as the immunosubstrate and Ag NCs as the immunoprobes was presented for ultralow level prostate-specific antigen (PSA) detection. Experimentally, the Ag NP/PorC film was first prepared with a facile method by carbonizing the gelatin-AgNO3 film in air, and Ag NCs were synthesized by the hydrothermal method. Then, the Ag NP/PorC film was modified by PSA antibodies as the substrate, while Ag NCs were decorated by R6G and PSA antibodies for probes. The sandwiched SERS detection embodiment was constructed by the immunoreaction between the PSA and PSA antibody predecorated on the substrate and probes. Our results show that the proposed SERS-type immunoassay is highly sensitive and selective to a wide range of PSA concentrations from 10-5 to 10-12 g/mL. Thereafter, it was also implemented to detect the PSA level in human serum, and the results successfully reproduce the PSA levels as those measured by the chemiluminescence method with a recovery rate above 90%. All in all, this SERS-type immunoassay provides a promising method for the early diagnosis of prostate cancer.

Large-Scale Moth-Eye-Structured Roll Mold Fabrication Using Sputtered Glassy Carbon Layer and Transferred Moth-Eye Film Characterization.

Currently, there is high demand for the development of a highly mass-producible technology for manufacturing moth-eye-structured films with an antireflection function. Conventional moth-eye-structured films have been produced by roll-to-roll (RTR) ultraviolet nanoimprint lithography (UV-NIL) using porous alumina, but the process of manufacturing the roll mold with aluminum is both complicated and time-consuming. To solve this problem, we proposed a sputtering process for forming a thin film of glassy carbon on a roll substrate and fabricated a moth-eye structure through the irradiation of oxygen plasma. A glassy carbon (GC) moth-eye-structure roll mold with a uniform reflectance of less than 0.1% over a length of 1560 mm was fabricated following this method. In addition, a superhydrophobic moth-eye-structured film was produced by RTR UV-NIL using the proposed roll mold, which exhibited a reflectance of 0.1%. In this study, a moth-eye-structure roll using porous alumina was compared with a film transferred from it. The GC moth-eye-structure roll mold was found to be superior in terms of antireflection, water repellency, and productivity. When the proposed large-area GC moth-eye-structured film was applied to window glass, significant anti-reflection and water-repellent functionalities were obtained.

Unrevealing tunable resonant excitons and correlated plasmons and their coupling in new amorphous carbon-like for highly efficient photovoltaic devices

An understanding on roles of excitons and plasmons is important in excitonic solar cells and photovoltaic (PV) technologies. Here, we produce new amorphous carbon (a-C) like films on Indium Tin Oxide (ITO) generating PV cells with efficiency three order of magnitude higher than the existing biomass-derived a-C. The amorphous carbon films are prepared from the bioproduct of palmyra sap with a simple, environmentally friendly, and highly reproducible method. Using spectroscopic ellipsometry, we measure simultaneously complex dielectric function, loss function as well as reflectivity and reveal coexistence of many-body resonant excitons and correlated-plasmons occurring due to strong electronic correlations. X-ray absorption and photoemission spectroscopies show the nature of electron and hole in defining the energy of the excitons and plasmons as a function of N or B doping. Our result shows new a-C like films and the importance of the coupling of resonant excitons and correlated plasmons in determining efficiency of photovoltaic devices.