Seawater is the most abundant resource on earth, so developing cost-effective, highly durable corrosion resistance and efficient electrocatalysts are crucial to enhance seawater splitting. Herein, we prepared 3D bristlegrass-like Co-doped Ni2P (Co-Ni2P) composites supported on Ni foam (NF) through a facile solvothermal method combined and a subsequent phosphatization treatment. Benefiting from the unique structure, Co-Ni2P shows excellent electrocatalytic activity as an electrode material for both the hydrogen evolution reaction (HER, low overpotential of 116 mV at 50 mA cm?2) and oxygen evolution reaction (OER, low overpotential of 266 mV at 50 mA cm?2). Moreover, the as-prepared Co-Ni2P composites exhibit excellent stability and corrosion resistance in an alkaline medium. Density functional theory (DFT) calculations were employed to evaluate the H1 adsorption of Co-Ni2P, and the results proved the high catalytic activity for the HER. This study provides new materials with a unique morphology for overall water splitting. 相似文献
Two-dimensional (2D) nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004, due to their intriguing physicochemical properties and wide-ranging applications in catalysis, energy-related devices, electronics and optoelectronics. To maximize the potential of 2D nanomaterials for their technological applications, controlled assembly of 2D nanobulding blocks into integrated systems is critically needed. This mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures, from in-situ assembly method to post-synthesis assembly. The applications of 2D assembled integrated structures are also covered, especially in the areas of energy, electronics and sensing, and we conclude with discussion on the remaining challenges and potential directions in this emerging field.
Energy bands, effective mass of carriers, absolute band edge positions and optical properties of tetragonal AgInS2 were calculated using a first-principles approach with the exchange correlation described by B3LYP hybrid functional. The results indicate that tetragonal AgInS2 has a direct band gap of 1.93 eV, which reproduce well experimental value. Calculated effective masses of electrons and holes are both small which are beneficial to separation and migration of electron and hole pairs. This implies that AgInS2 has good photocatalytic performance. The calculated optical characteristics indicate that AgInS2 has a slight anisotropy for both the real and imaginary parts of the dielectric function and exhibits large optical absorption in the visible light region. Furthermore, the calculated band edge positions in (100), (010) and (001) surfaces indicate that tetragonal AgInS2 is beneficial to the reduction and oxidation of water to hydrogen and oxygen under visible light irradiation. 相似文献
The lead-free Ba0.53Sr0.47TiO3 (BST) thin films buffered with La0.67Sr0.33MnO3 (LSMO) bottom electrode of different thicknesses were fabricated by pulsed laser deposition method on a (001) SrTiO3 substrate. It was found that the roughness of electrode decreases and substrate stress relaxes gradually with the increase of LSMO thickness, which is beneficial for weakening local high electric field and achieving higher Eb. Therefore, the recoverable energy density (Wrec) of BST films can be greatly improved up to 67.3 %, that is, from 30.6 J/cm3 for the LSMO thickness of 30 nm up to 51.2 J/cm3 for the LSMO thickness of 140 nm after optimizing the LSMO thickness. Furthermore, the thin film capacitor with a 140 nm LSMO bottom electrode shows an outstanding thermal stability from 20 °C to 160 °C and superior fatigue resistance after 108 electrical cycles with only a slightly decrease of Wrec below 1.6 % and 3.7 %, respectively. Our work demonstrates that optimizing bottom electrodes thickness is a promising way for enhancing energy storage properties of thin-film capacitors. 相似文献
In this work, TiO2 nanoparticles are surface modified by NH2-terminated organic moieties arised from 4,4′-methylene diphenyl diisocyanate (MDI). These nanoparticles are incorporated into ether-based segmented polyurethane (SPU) matrix. MDI is utilized as monomer together with poly(tetramethylene oxide) (PTMO) comonomer for preparing the final polymer as well. The NH2-functionalized TiO2 nanoparticles are covalently linked to the NCO terminals of the resulting SPU macromolecules during film preparation stage. Therefore, in addition to butylene glycol, these surface modified nanoparticles with enhanced organophilicity could play the role of the second chain extender of NCO-capped SPU macromolecules through formation of urea linkages. Optical and thermal behaviors of the transparent and flexible film (SPU/TiO2–MDI) is compared with those of unmodified TiO2 (SPU/TiO2) and TiO2-unloaded SPU films. Though the particle loading is only 5 wt.%, incorporation of TiO2 and TiO2–MDI nanoparticles into the SPU polymer enhances significantly the light absorption in UV region at 300–400 nm. SEM images of the prepared films clearly show a considerable decrease in particle aggregation for TiO2–MDI into SPU matrix compared to that of unmodified TiO2. TG analyses indicate a one-step decomposition pattern with onset temperatures of about 360 and 380 °C for neat SPU and SPU/TiO2–MDI, respectively. Moreover, DTA thermograms of both nanocomposites show obviously two exothermic phase transitions in the thermal range of 330–440 °C. 相似文献
The influence of the environment on the excited state transitions of meso-tetrakis(p-sulfonatophenyl) porphyrin (TPPS) is reported. TPPS was investigated in protonated and non-protonated forms, and in the presence of the cationic cetyltrimethylammonium bromide (CTAB) micelles. The singlet excited-state absorption spectra were measured by using the white-light continuum Z-scan technique and the triplet–triplet absorption spectra were acquired employing an association of laser flash photolysis and Z-scan techniques. Our results show that the perseveration of the molecular symmetry, upon excitation, depends on the state of multiplicity of the molecules, as well as on the environment and structural characteristics of the porphyrin. Additionally, it was observed that for excited molecules, the ring distortion caused by the protonation of porphyrin ring has great influence on the changes observed for the symmetry and vibronic structure. The results clearly show that the porphyrin investigated is a promising candidate for optical limiting applications for all investigated environments. 相似文献
Carbon fibers have been processed from gel spun polyacrylonitrile copolymer on a continuous carbonization line at Georgia Tech (GT) with a tensile strength in the range of 5.5–5.8 GPa, and tensile modulus in the range of 354–375 GPa. This combination of strength and modulus is the highest for any continuous fiber reported to date, and the gel spinning route provides a pathway for further improvements in strength and modulus for mass production of carbon fibers. At short gauge length, fiber tensile strength was as high as 12.1 GPa, which is the highest value ever reported for a PAN based carbon fiber. Structure analysis shows random flaws of about 2 nm size, which results in limiting tensile strength of higher than 20 GPa. Inter-planar turbostratic graphite shear modulus in high strength carbon fibers is 30 GPa, while in graphite the corresponding value is only 4 GPa. 相似文献
Coordination chemistry, bond state and vibrational spectrum of co-substituted microwave dielectric NdNb1-x(Zr0.5W0.5)xO4 ceramics (x = 0.01∼0.05) were investigated. Raman spectra and XRD refinement showed a solid solution was formed. The compressed and elongated chemical bonds are responsible for the variations of crystal parameters and cell volume. Calculated chemical bond parameters indicated bond covalency, lattice energy and Nb-site bond energy act on the fluctuations of the permittivity, quality factor and temperature coefficient, respectively. Meanwhile, the infrared vibrational spectrum is fitted to quantify the contributions of observed IR mode to the intrinsic loss. Compact ceramic possesses excellent properties: εr ∼ 19.2, Q × f ∼ 55282 GHz and τf ∼ -11.36 ppm/°C with x = 0.04, at 1250°C. 相似文献
Nano Research - We report the composition and back-gate voltage tuned transport properties of ternary compound Bi2(Te1−xSex)3 nanowires synthesized by chemical vapor deposition (CVD). It is... 相似文献