Search

In order to explore a new electrocatalyst (or its precursor) for oxygen evolution reaction (OER), much attention has recently been given to the alternative engineering strategy for fabricating a novel nanofilm electrode with high efficiency and long duration. We herein use a two-step electrodeposition method to prepare a series of nanofilm electrodes containing Ni, Co, P, and Se on carbon cloth. After a suitable electrochemical activation process through cyclic voltammetry, the resultant binder-free NiCoP–NiCoSe₂ nano-bilayer films are transformed from compact layer(s) to porous nanoparticle ones composed by NiCo hydroxides and a small amount of NiCo oxyhydroxides and thus exhibit a striking electrocatalytic activity (lower to 243 mV overpotential for 10 mA cm–²) and excellent stability (80 h) for OER. The rougher surface, well-suited electronic structure originated from the Ni/Co codoping and the rational integration of NiCoP and NiCoSe₂ are important factors for the excellent OER performance of the NiCoP–NiCoSe₂ film after the electrochemical activation process. In addition, the results on overall water splitting reveal that the NiCoP–NiCoSe₂ film is also promising in the practical application of energy conversion and storage.

Porphyrin and phthalocyanine complexes bearing single-atom catalytic sites (M-N

Active and durable electrocatalyst for hydrogen evolution reaction (HER) is pivotal to generate molecular hydrogen more energy-efficient, but directly grafting electrocatalyst on electrode material by a single-step method without compromising the catalytic activity and stability remains a challenge. Herein, an intriguing electrode, reduced graphene oxide modified carbon nanotube/reduced graphene oxide/polyphenylene sulfide (RGO-CNT/RGO/PPS) film, is used to replace conventional electrodes. In situ electrodeposition is proposed to fabricate CoP on the RGO-CNT/RGO/PPS (CoP-RGO-CNT/RGO/PPS) electrode and achieves a favorably electrical contact between CoP nanoparticles and RGO-CNT/RGO/PPS electrode due to without any polymer binder. Additionally, the coupling of different electrodeposition stages with scanning electron microscope (SEM) can investigate the nanostructure evolution of CoP nanoparticles, which gives valuable insights into the optimized electrodeposition cycles. The rational integration of RGO onto CNT/RGO/PPS film is an effective approach for enhancing its intrinsic electrical conductivity and favoring the formation of a high density of dispersive CoP nanoparticles. The CoP-RGO-CNT/RGO/PPS film has shown outstanding HER electrocatalytic behaviors performed a current density of 10 mA cm−2 at a relatively low overpotential of 160 mV with a Tafel slope of 60 mV dec−1 in acidic medium, which can be mainly attributed to the synergistic effect between optimized morphology and accelerated kinetics. Additionally, this film electrocatalyst exhibits a good HER activity and stability under both neutral and basic conditions.

Through annealing and electrochemical reduction methods, we successfully fabricates reduced graphene oxide layer (RGOL) modified carbon nanotube and reduced graphene oxide (CNT + RGO) doped polyphenylene sulfide (PPS) flexible thin film electrodes. These composite structure films can not only overcome the brittle nature of PPS, but also make good use of the thermal stability of PPS. Furthermore, carbon nanotube and reduced graphene oxide enhance the electrical conductivity of the composite films. Truncated octahedral and cuboctahedral Cu2O nanocrystals are synthesized on RGOL modified CNT + RGO doped PPS (RGOL@PPS/CNT + RGO) composite film by a facile electrodeposition method without using any surfactants or external heating. RGOL on the PPS/CNT + RGO substrate facilitates the formation of Cu2O morphology. The obtained Cu2O composite film shows a superior ability for the hydrogen evolution reaction (HER) compared with other Cu2O electrocatalysts. The Cu2O with a smaller loading less than 0.04 mg cm−2 on the composite film exhibits excellent HER activities with a low onset potential of 0.05 V and large current densities. The results of the HER performance indicates that the RGOL@PPS/CNT + RGO composite film has a potential application in flexible hydrogen-producing devices.

The low-cost and efficient electrocatalysts for oxygen evolution reaction (OER) hold a key to sustainable energy conversion. Here, a novel flower-like Co-Ni alloy was fabricated on the polyimide-carbon nanotube (PI-CNT) film by the double step potential deposition method. The nanostructure of Co-Ni alloy and the underlying PI/CNT film result a great catalytic OER performance of Co-Ni/PI-CNT film. The obtained results indicated Co-Ni(1:1)/PI-CNT film performed the best electrocatalytic property comparing with that of the Co-Ni/PI-CNT films with other atomic ratio. Besides, the deposition times played an important role to effect the OER activity of films and the research confirmed the Co-Ni(100s)/PI-CNT film was the best one. The prepared Co-Ni(1:1,100s)/PI-CNT film exhibited an earlier onset potential about 1.50 V and a small Tafel slope of 59 mV/decade. The facile electrodeposition synthesis of such efficient catalyst based on mixed-metals provides a new way for the rational design of high-performance catalyst for water splitting.

Porphyrin and phthalocyanine complexes bearing single-atom catalytic sites (M-N4 ) have been explored as promising electrocatalysts for CO2 reduction reaction (CO2 RR), whose activity can be improved by regulating the ligands and/or the metal centers. Moreover, their photosensitive features also provide the possibility for highly efficient photoelectrocatalytic CO2 RR. Herein, a novel N'NN'-pincer-ligand (N3 )-coupled cobalt porphyrin (CoPor-N3 ) polymer is developed for realizing efficient (photo)electrocatalytic CO2 RR. The unraveled electronic structure and (photo)electrocatalytic features suggest that a synergistic effect between the electron-rich N3 ligands and the Co-N4 single-atom sites in the CoPor-N3 polymer results in the Co centers attaining more electrons, which is beneficial to facilitating the electron transfer to CO2 for the activation and reduction processes. As expected, the resultant CoPor-N3 polymer delivers a good long-term durability and high CO faradaic efficiency (96%) at an ultralow overpotential (0.39 V), which outperforms the CoPor alone and most porphyrin-/phthalocyanine-based electrocatalysts reported so far. Moreover, the photosensitivity of CoPor units can further reduce the overpotential to 0.34 V with a CO faradaic efficiency over 90% under light illumination. The present findings offer a new approach to constructing porphyrin-based photosensitive electrocatalysts with high-efficiency photoelectrocatalytic CO2 RR.

Energetic catalyst for electrochemical CO2 conversion into high value-added chemicals is critical. Herein, an ethynyl-linked cobalt(II) porphyrin conjugated polymer (PCP) is decorated on the carbon nanotubes (CNTs) to fabricate bi-metallic central electrocatalyst (CoCoPCP/CNTs) for electrochemical CO2 reduction (CO2 RR). By regulating the porphyrins’ central sites of the PCP, the resultant CoCoPCP/CNTs performs a high CO faradic efficiency of 94 % with a TOF of 2.4 s−1 at an extremely low overpotential of 0.44 V, which are much better than that of its CNTs-containing analogues. The effects of central site on the electrocatalytic performance and its mechanism are discussed based on the experimental study and theoretical calculation, and it is found that both of the Co centers in the four- and two-linked porphyrin units of the CoCoPCP are critical for CO2 RR. The present work should be of significance for the exploration of porphyrin-based conjugated polymers as energetic electrocatalyst in CO2 reduction.

Photocatalytic CO2 reduction to solar fuels is considered as a promising strategy to address the global warming and energy shortages. Herein, a novel method is proposed to prepare g-C3N4/ZnO nanocomposites via refluxing zinc salt methanol solution containing pre-formed g-C3N4 with KOH methanol solution as precipitating agent. Some in-situ grown ultrafine ZnO nanoparticles are decorated on ultrathin g-C3N4 layers with well-defined interface, which not only causes efficient charge transfer and separation, but also creates more active sites for CO2 adsorption and activation. The resultant g-C3N4/ZnO composites demonstrate significant enhanced CO2 photoreduction activity and selectivity for CH4 production under visible light irradiation, and the optimal g-C3N4/ZnO composite delivers the best overall photoactivity (158.4 μmol g−1 h−1) with CH4/CO production rates of 19.8/0.37 μmol g−1 h−1, which is 9.42 times higher than that of g-C3N4 alone. This work provides an ideal synthetic strategy for g-C3N4-based hybrid materials with highly efficient CO2 photoreduction.

An efficient electrocatalyst based earth-abundant materials for hydrogen evolution reaction (HER) is a prerequisite for improving the efficiency of producing hydrogen. However, the synthesis of such electrocatalysts by a simple and environmentally friendly method is still a tremendous challenge. Herein, NiSe nanoparticles were in situ deposited on the reduced graphene oxide-polyimide/carbon nanotube (RGO-PI/CNT) film by a green electrodeposition method. The NiSe nanoparticles on the RGO-PI/CNT (NiSe-RGO-PI/CNT) film was employed directly as a highly active HER electrocatalyst. The RGO-PI/CNT film allowed NiSe nanoparticles to grow rapidly on its surface. NiSe nanoparticles with a small size of 35-45 nm were distributed uniformly on the surface of the RGO-PI/CNT film. The good dispersity of NiSe nanoparticles permitted the exposure of more active sites, which enhanced the activity of HER on the NiSe-RGO-PI/CNT film. The NiSe-RGO-PI/CNT film performed well HER behaviors featured by a low overpotential (270 mV), a small Tafel slope (61 mV dec(-1)) and a considerable stability. The efficient HER performance of the NiSe-RGO-PI/CNT film was originated from the synergistic effect between the RGO-PI/CNT film and NiSe nanoparticles. This exploration provided a straightforward and green method to prepare a film electrocatalyst for HER. (C) 2017 Elsevier Ltd. All rights reserved.

This work has demonstrated for the first time that MoTe2 nanodendrites can be used as an electrocatalyst toward the hydrogen evolution reaction (HER) in neutral solution. MoTe2 nanodendrites are deposited on Mo doped reduced graphene oxide/polyimide (RGO/PI/Mo) composite substrate by electrochemical method. The nanodendrites structure of MoTe2 and the underlying RGO/PI/Mo substrate facilitate the good HER performance of MoTe2-RGO/PI/Mo film in neutral medium. Especially under illumination condition, it has a greater cathode current at more positive potential. Furthermore, MoTe2 nanodendrites have excellent photo-responsive property, and the potential difference could reach 100 mV. Raman spectroscopy reveals that prepared MoTe2 belongs to 1T-MoTe2. The comparison between MoTe2-RGO/PI/Mo composite film and other catalysts indicate that the MoTe2-RGO/PI/Mo film have a greater performance for HER in neutral solution, which opens up a promising pathway for the exploration of high-efficiency neutral electrocatalysts for HER.

The collector consumption for anthracite coal flotation is higher than that of coking coal. In the present study, dodecane and nonyl benzene were evaluated for anthracite flotation. The surface free energy and interfacial interaction energy were calculated to identify the interaction mechanism between coal and dodecane/nonyl benzene from the perspective of thermodynamics. The results showed that anthracite coal was rich in benzene ring groups, and flotation performance of anthracite coal using nonyl benzene was better than that of using dodecane. The interfacial interaction free energy between anthracite coal and nonyl benzene was much higher than that of dodecane. Nonyl benzene interacts with aromatic sites on the coal surface through Pi-bonding, resulting in a high flotation recovery.

A traditional hydrocarbon collector dodecane and an oxygen-containing collector α-furanacrylic acid were selected for oxidized coal flotation in the present study, respectively. The changes of the surface functional groups and zeta potential of oxidized coal were measured before and after α-furanacrylic acid absorption and the electro-negativity of functional groups in α-furanacrylic acid was calculated to indicate its absorption mechanism on oxidized surface. Surface free energy and interfacial interaction energy were calculated to identify the interaction mechanism between coal and α-furanacrylic acid from the perspective of thermodynamics. Results show that 53.80% flotation yield with 14.03% ash content was obtained when 7000 g/t dodecane was used. In contrast, 69.17% yield with 11.98% ash content could be obtained only using 931 g/t α-furanacrylic acid. The high flotation recovery was attributed to the hydrogen bonding function between α-furanacrylic acid ( COOH and oxygen-containing five-memered rings) and oxidized coal surface. The interfacial interaction energy is 21.20 mN ∙ m − 1 for coal-water-α-furylacrylic acid system while − 23.09 mN ∙ m − 1 for coal-water-dodecane system. A repulsive hydration force was found between oxidized coal and α-furylacrylic acid via water phase. α-Furanacrylic acid could not form hydrogen bond directly with the oxygen-containing functional groups on coal surface. Instead, the water molecules in hydration film may act as the bridging role of hydrogen bond for α-furanacrylic acid absorption on oxidized coal surface.

Flexible inorganic electronics (FIE) have shown unique advantages in energy conversion, aerospace and wearable devices due to excellent electronic properties and thermostability of inorganic materials. The industrialization of high-performance flexible inorganic electronics (FIE) devices requires universal approaches to fabricate inorganic crystal on polymer substrates at acceptable temperature. Herein, we firstly developed the vortex flow chemical vapor deposition (VFCVD) for low temperature synthesis of high-quality vertical ReO2 arrays at 450 °C on flexible graphene-polyimide (G-PI) conductive film. The Euler equations suggest that the vapor pressure of ReO2 is almost 100-times higher than that of free space with VFCVD at identical conditions. The derived ReS2/ReO2 metal-semiconductor heterojunction arrays are performed outstanding hydrogen evolution reaction (HER) activity with high long-term stability as an energy conversion device. This work opens up an opportunity for low temperature growth of inorganic nanomaterials on polymer substrates by VFCVD for the industrialization of high-performance flexible energy devices.

Deposition of fibronectin and collagen in the extracellular matrix (ECM) and the proliferation, migration, and hypertrophy of vascular smooth muscle cells (VSMCs) result in pulmonary arterial (PA) hypertrophy and muscularization, leading to increased pulmonary vascular resistance in pulmonary arterial hypertension (PAH). MicroRNA29 (miR-29) is reported to be associated with diseases such as liver fibrosis, renal fibrosis, pulmonary fibrosis, and cardiac fibrosis in which collagen synthesis plays an important role. Due to the possible link between PAH and collagen, in this study, we examined the role and therapeutic potential of miR-29b in vitro and in a rat model of pulmonary hypertension induced by monocrotaline (MCT). Results revealed that miR-29b treatment PAH rats showed a lower level of collagen synthesis. Furthermore, in pulmonary arterial smooth muscle cells (PASMCs), TGFβ1/Smad3 signaling negatively regulated the expression of miR-29b, and miR-29b suppressed collagen synthesis by directly targeting collagen I and blocking PI3K/AKT signaling. In addition, TGF-β1/Smad3 signaling promoted collagen synthesis in PASMCs by down-regulating miR-29b. Interestingly, Smad3 decreased the expression of miR-29b by interacting with its promotor. In conclusion, our results revealed that miR-29b plays an important role in collagen synthesis and may be a therapeutic target for PAH when regulated by the TGF-β1/Smad3 pathway.

The future of energy supply depends on innovative breakthroughs in the development of highly efficient, sustainable and low-cost systems for renewable energy conversion and storage. Water splitting is a promising and appealing solution. In this work, we report Co(OH)2 on the carbon nanotube/polyimide film (PI/CNT-Co(OH)2) as an efficient electrocatalyst for the oxygen evolution reaction (OER). The PI/CNT film allows intimate growth of Co(OH)2 nanosheets on its surface. The nanosheet structure of Co(OH)2 and the underlying PI/CNT film facilitate the good OER performance of the PI/CNT-Co(OH)2 film. Co(OH)2 nanosheets on the PI/CNT film afford an earlier onset of oxygen evolution, a low overpotential of 317 mV and a small Tafel slope of 49 mV per decade in alkaline media. This work applies the PI/CNT film in water splitting to enhance the OER electrocatalytic activity of Co(OH)2, which opens up a promising avenue for the exploration of highly active electrocatalysts that can replace noble-metal based catalysts for the OER.

Diamond-like carbon (DLC) films were deposited on Al substrates by electrodeposition technique under various voltages. The surface morphology and compositions of synthesized films were characterized by scanning electron microscopy and Raman spectroscopy. With the increase of deposition voltage, the sp2 phase concentration decreased and the surface morphology changed dramatically. The influence of deposition voltage on the field electron emission (FEE) properties of DLC films was not monotonic due to two adverse effects of deposition voltage on the surface morphology and compositions. The DLC film deposited under 1200 V exhibited optimum FEE property, including a lowest threshold field of 13 V/μm and a largest emission current density of 904.8 μA/cm2 at 23.5 V/μm.

Nanocrystalline GaN film was prepared by direct current magnetron sputtering. X-ray diffraction and transmission electron microscopy confirmed the presence of hexagonal phase GaN crystallites with particle size of 5 nm. The I – V characteristic of the Al/nc-GaN contacts can be understood in terms of the current transport mechanism of space-charge-limited current. Analysis of the I – V data indicates an equilibrium electron concentration of 8.1 × 10 14 cm −3 and the thermal equilibrium Fermi level located 0.27 eV below the conduction band edge. Only one deep level located at 0.364 eV below the conduction band with capture cross-section of 1.74 × 10 −18 cm 2 was found in the film by Q-DLTS. A simple analysis has been used to identify this deep level.

Nitrogen incorporated diamond-like carbon (DLC:N) films with different N content were deposited on Si(1 0 0) substrates by electrolysis of urea/methanol organic solution with different mole ratios under a constant voltage of 600 V. Analysis by Raman spectrometry and X-ray photoelectron spectrometry (XPS) shows that N is incorporated into the DLC films by sp 3 C–N and sp 2 C N bonds and induces graphitization of the films. The electronic field emission properties of these films have been studied using a parallel plate configuration, and the dependence on N content investigated. The turn-on field ( E c ) is lowered with increasing N content, and there is a simultaneous rise in the field emission current densities under the electric field of 23.5 V/μm. Enhancement in field emission is attributed to the donor activity of nitrogen and the field enhancement effect of sp 2 clusters.

Copper nitride (Cu 3 N) thin film was deposited on silicon (Si) substrate by reactive magnetron sputtering method. X-ray diffraction measurement showed that the film was composed of Cu 3 N crystallites with anti-ReO 3 structure and exhibited preferential orientation of [1 0 0] direction. The field emission (FE) result showed that Cu 3 N film had a turn-on electric field of about 3 V/μm at a current density of 1 μA/cm 2 and a current density of 700 μA/cm 2 was obtained at the electric field of 24 V/μm. The emission mechanism inferred by Fowler-Nordheim (FN) plot is shown as following: thermal electron emission at low field region and tunneling electron emission at high field region.

Samples of gadolinium-calcium ferrites Gd1−xCaxFeO3− y, with x ranging from 0 to 2 3 were synthesized in air by solid state reaction. The X-ray powder diffraction studies reveal that the produced samples are one-phased orthorhombic perovskite compounds having the space group D2h16-Pbnm. The lattice constants of the Gd1− xCaxFeO3−y, samples have been determined by Cohen's least-squares method. The variation of the lattice constants with x is presented. The initial substitution of Ca for Gd gives rise to a decrease of the lattice constants. Further substitution of Ca for Gd has little influence on the lattice dimensions.

Samples of dysprosium-calcium ferrites Dy1−xCaxFeO3−x with x ranging from 0 to 2 3 were novelly prepared in air by solid state reaction and characterized by X-ray powder diffraction. These samples are single-phased orthorhombic perovskite-type compounds belonging to the space group D2h16-Pbnm. The lattice constants of the Dy1−xCaxFeO3−x samples have been refined by Cohen's least-squares method. The initial substitution of Ca for Dy leads to a decrease of the lattice constants. Further substitution of Ca for Dy has hardly any influence on the lattice dimensions.