Along with the technology evolution for dense integration of high-power, high-frequency devices in electronics, the accompanying interfacial heat transfer problem leads to urgent demands for advanced ...thermal interface materials (TIMs) with both high through-plane thermal conductivity and good compressibility. Most metals have satisfactory thermal conductivity but relatively high compressive modulus, and soft silicones are typically thermal insulators (0.3 W m–1 K–1). Currently, it is a great challenge to develop a soft material with the thermal conductivity up to metal level for TIM application. This study solves this problem by constructing a graphene-based microstructure composed of mainly vertical graphene and a thin cap of horizontal graphene layers on both the top and bottom sides through a mechanical machining process to manipulate the stacked architecture of conventional graphene paper. The resultant graphene monolith has an ultrahigh through-plane thermal conductivity of 143 W m–1 K–1, exceeding that of many metals, and a low compressive modulus of 0.87 MPa, comparable to that of silicones. In the actual TIM performance measurement, the system cooling efficiency with our graphene monolith as TIM is 3 times as high as that of the state-of-the-art commercial TIM, demonstrating the superior ability to solve the interfacial heat transfer issues in electronic systems.
With the increasing integration of devices in electronics fabrication, there are growing demands for thermal interface materials (TIMs) with high through-plane thermal conductivity for efficiently ...solving thermal management issues. Graphene-based papers consisting of a layer-by-layer stacked architecture have been commercially used as lateral heat spreaders; however, they lack in-depth studies on their TIM applications due to the low through-plane thermal conductivity (<6 W m–1 K–1). In this study, a graphene hybrid paper (GHP) was fabricated by the intercalation of silicon source and the in situ growth of SiC nanorods between graphene sheets based on the carbothermal reduction reaction. Due to the formation of covalent C–Si bonding at the graphene–SiC interface, the GHP possesses a superior through-plane thermal conductivity of 10.9 W m–1 K–1 and can be up to 17.6 W m–1 K–1 under packaging conditions at 75 psi. Compared with the current graphene-based papers, our GHP has the highest through-plane thermal conductivity value. In the TIM performance test, the cooling efficiency of the GHP achieves significant improvement compared to that of state-of-the-art thermal pads. Our GHP with characteristic structure is of great promise as an inorganic TIM for the highly efficient removal of heat from electronic devices.
In this work, we proposed a novel modification technique to immobilize nanoparticles by the nanopores on a boron-doped diamond surface, preventing the aggregation of nanoparticles physically and ...improving the stability of nanoparticles layer by the anchoring effect. All the exposed surfaces of a bare boron-doped diamond were etched into nanoporous form and larger electrochemically active surface area was obtained on the porous boron-doped diamond electrode. The carbon black nanoparticles modified porous boron-doped diamond electrode showed good selectivity to separate the oxidation potential of three molecules, but led to an extra increase in the peak current of dopamine (DA). The carbon black/Nafion modified porous diamond electrode effectively suppress the oxidation current of ascorbic acid (AA), enhancing the sensitivity of DA. The dual layer treatment enables a wide linear range, 0.1–100 μM and a low limit of detection, 54 nM for DA detection, which is almost unaffected by the excess AA and uric acid (UA). At last, real sample tests of the carbon black/Nafion modified porous diamond electrode was validated by applying to the detection of DA in human serum and dopamine hydrochloride injection, which were found to be promising at our preliminary experiments. Additionally, the fabricated carbon black/Nafion modified porous diamond electrode also demonstrated good stability and long-term functionality.
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•A novel modification on porous boron-doped diamond electrode for determination of dopamine was developed.•The elimination of the interference was realized and a low detection limit of 54 nM for DA was obtained.•Reproducibility of the CB-Nafion/p-BDD electrode in real sample and excess interferents was validated.•Excellent stability and long-term functionality of the CB-Nafion/p-BDD electrode were confirmed.
In vivo tracking or in vitro real sample analysis by electrochemistry is one of the most straight and useful methods in biosensor field. However, surface biofouling of electrodes by non-specific ...protein adsorption is inevitable and usually leads to a decrease in sensitivity. Here, we developed a Nafion-coated porous boron-doped diamond (NAF/pBDD) electrode with hydrophobic nanostructures to minimize the biofouling effect and selectively detect dopamine (DA). Larger active area was obtained by this procedure compared to a bare diamond electrode. The as-prepared electrode shows excellent antifouling property and enrichment capacity toward selective detection of dopamine (DA). The low background current of the BDD electrode and the enhanced signals enables a lower detection limit, 42 nmol L
−1
, and a wider linear range, 0.1–110 μmol L
−1
, for determination of DA in human serum. Additionally, the facile modified electrode demonstrated renewable property and long-term stability due to the fact that the antifouling nanostructures belong to its own.
Graphene is usually embedded into polymer matrices for the development of thermally conductive composites, preferably forming an interconnected and anisotropic framework. Currently, the directional ...self‐assembly of exfoliated graphene sheets is demonstrated to be the most effective way to synthesize anisotropic graphene frameworks. However, achieving a thermal conductivity enhancement (TCE) over 1500% with per 1 vol% graphene content in polymer matrices remains challenging, due to the high junction thermal resistance between the adjacent graphene sheets within the self‐assembled graphene framework. Here, a multiscale structural modulation strategy for obtaining highly ordered structure of graphene framework and simultaneously reducing the junction thermal resistance is demonstrated. The resultant anisotropic framework contributes to the polymer composites with a record‐high thermal conductivity of 56.8–62.4 W m−1 K−1 at the graphene loading of ≈13.3 vol%, giving an ultrahigh TCE per 1 vol% graphene over 2400%. Furthermore, thermal energy management applications of the composites as phase change materials for solar‐thermal energy conversion and as thermal interface materials for electronic device cooling are demonstrated. The finding provides valuable guidance for designing high‐performance thermally conductive composites and raises their possibility for practical use in thermal energy storage and thermal management of electronics.
The dual‐assembled graphene framework (DAGF), which combines a highly oriented graphene structure along the vertical direction and a low junction thermal resistance between the graphene building blocks, exhibits excellent performance in improving the thermal conductivity of polymers. The resultant composites have a record‐high thermal conductivity of 56.8–62.4 W m−1 K−1(≈13.3 vol%), significantly outperforming previously reported results.
Selective detection of dopamine is still a challenge due to the strong interference from ascorbic acid (AA). A hybrid dopamine electrochemical sensor was fabricated by boron-doped diamond (BDD) film ...co-modified with gold nanoparticles and graphite-coated nickel nanoparticles (Au-C@Ni/BDD). Highly sensitive and selective detection toward dopamine was achieved by multiple electrochemical anodic polarization treatment (EAPT) with relatively mild voltage (+ 1.6 V vs. Ag/AgCl) on Au-C@Ni/BDD electrode. Specifically, the oxidation peak separation between ascorbic acid and dopamine reached 166 mV, and the limit of detection of dopamine was as low as 0.015 μM in a linear concentration range of 0.05–100 μM with the sensitivity up to 1.99 μA μM
−1
cm
−2
even in the presence of interference of high-level AA. These could be ascribed to the electrocatalytically active sites and functional oxygen-containing groups of the hybrid electrodes produced by the EAPT and the excellent catalytical activity of gold nanoparticles.
Graphical Abstract
•Successful growth of Cu3BiS3 thin films using thermal evaporation.•Growth temperature enhances the photoelectric properties of Cu3BiS3 thin films.•Cu3BiS3 solar cell absorber was successfully ...implemented in solar cell device.
Ternary copper sulphides, especially copper-bismuth-sulphide (Cu-Bi-S), are alternative solar absorber materials due to their earth-abundant and non-toxic constituent elements, compared to the conventional copper indium gallium sulphide and cadmium telluride films. In this study, Cu-Bi-S thin films were deposited onto soda lime glass substrates using a one stage co-evaporation process from Cu2S and Bi2S3 sources, with the deposition temperatures varied from room temperature to 400 °C. X-ray diffraction analysis confirmed that Cu3BiS3 was the dominant phase in the Cu-rich films, and the crystalline quality of the films was significantly improved with increasing the deposition temperature. An optical bandgap of 1.4 eV was achieved for the film deposited at 400 °C, which demonstrated a Hall mobility of 3.95 cm2/V-s and a carrier concentration of 7.48 × 1016 cm−3. Cu3BiS3 films deposited at 375 and 400 °C were implemented into superstrate solar cell structures (glass/ITO/n-CdS/p-Cu3BiS3/Al).
Chloramphenicol (CAP) is a harmful compound associated with human hematopathy and neuritis, which was widely used as a broad-spectrum antibacterial agent in agriculture and aquaculture. Therefore, it ...is significant to detect CAP in aquatic environments. In this work, carbon nanotubes/silver nanowires (CNTs/AgNWs) composite electrodes were fabricated as the CAP sensor. Distinguished from in situ growing or chemical bonding noble metal nanomaterials on carbon, this CNTs/AgNWs composite was formed by simple solution blending. It was demonstrated that CNTs and AgNWs both contributed to the redox reaction of CAP in dynamics, and AgNWs was beneficial in thermodynamics as well. The proposed electrochemical sensor displayed a low detection limit of up to 0.08 μM and broad linear range of 0.1-100 μM for CAP. In addition, the CNTs/AgNWs electrodes exhibited good performance characteristics of repeatability and reproducibility, and proved suitable for CAP analysis in real water samples.
A Ni/Cu/boron-doped diamond (Ni/Cu/BDD) complex electrode for non-enzymatic glucose electrochemical detection was prepared by a simple two-step heat treatment method. Scanning electron microscopy ...(SEM), Raman spectroscopy and electrochemical workstation were used to characterize the surface morphology, composition and electrochemical properties of the electrode, respectively. The results showed that Ni reacted with BDD under high temperature catalytic conditions forming a porous structure, and stabilized Cu on the surface of BDD due to the superior wettability between Cu and Ni. Compared to Ni/BDD and Cu/BDD electrodes, Ni/Cu/BDD electrode exhibited enhanced catalytic activity in glucose detection, such as an extremely wide detection range (0.022–18.3mM), high sensitivity (1007.688 μAmM−1cm−2, which was 1.28 times higher than that of the Ni/BDD electrode), great selectivity and excellent long-term stability (93.3% after one month).
•The Ni/Cu/BDD electrode exhibits excellent long-term stability because nickel particles are embedded into the diamond forming a porous structure, which avoids the peel-off of Ni/Cu NPs during the detection.•The Ni/Cu/BDD exhibits enhanced catalytic activity compared with Ni/BDD owing to the addition of Cu nanoparticles.•The synergistic effect of nickel nanoparticles, copper nanoparticles and BDD films is well discussed for the first time.
Nitric oxide (NO), an endogenous signaling molecule in animals and plants, mediates responses to abiotic and biotic stresses. Our previous work demonstrated that 100 μM sodium nitroprusside (SNP, an ...NO donor) treatment of maize seedlings increased K+ accumulation in roots, leaves and sheathes, while decreasing Na+ accumulation (Zhang et al. in J Plant Physiol Mol Biol 30:455-459, 20041. b). Here we investigate how NO regulates Na+, K+ ion homeostasis in maize. Pre-treatment with 100 μM SNP for 2 days improved later growth of maize plants under 100 mM NaCl stress, as indicated by increased dry matter accumulation, increased chlorophyll content, and decreased membrane leakage from leaf cells. An NO scavenger, methylene blue (MB-1), blocked the effect of SNP. These results indicated that SNP-derived NO enhanced maize tolerance to salt stress. Further analysis showed that NaCl induced a transient increase in the NO level in maize leaves. Both NO and NaCl treatment stimulated vacuolar H+-ATPase and H+-PPase activities, resulting in increased H+-translocation and Na+/H+ exchange. NaCl-induced H+-ATPase and H+-PPase activities were diminished by MB-1. 1-Butanol, an inhibitor of phosphatidic acid (PA) production by phospholipase D (PLD), reduced NaCl- and NO-induced H+-ATPase activation. In contrast, applied PA stimulated H+-ATPase activity. These results suggest that NO acts as a signal molecule in the NaCl response by increasing the activities of vacuolar H+-ATPase and H+-PPase, which provide the driving force for Na+/H+ exchange. PLD and PA play an important role in this process.
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