Two-dimensional Plane Structure Research Articles

A general synthetic strategy for N, P co-doped graphene supported metal-rich noble metal phosphides for hydrogen generation

The exploitation of electrocatalysts with high activity and durability for HER is desirable for future energy systems, but it is still a challenge. NMPs have attracted increasing attentions, but the preparation process often needs toxic regents or dangerous reaction conditions. Herein, we develop a general green method to fabricate metal-rich NMPs anchored on NPG through pyrolyzing DNA cross-linked complexes. The obtained Ru2P-NPG exhibits an ultrasmall overpotential of 7 mV at 10 mA cm−2 and ultralow Tafel slope of 33 mV dec−1 in 1.0 mol L−1 KOH, even better than that of commercial Pt/C. In addition, Ru2P-NPG also shows low overpotentials of 29 and 78 mV in 0.5 mol L−1 H2SO4 and 1.0 mol L−1 PBS, respectively. The superior activity can be attributed to the ultrafine dispersion of Ru2P nanoparticles for more accessible sites, more defects formed for abundant active sites, the two-dimensional plane structure for accelerated electron transfer and mass transport, as well as the regulation of electron distribution of the catalyst. Moreover, the synthetic method can also be applied to prepare other metal-rich noble metal phosphides (Pd3P-NPG and Rh2P-NPG), which also exhibits high activity for HER. This work provides an effective strategy for designing NMP-based electrocatalysts.

Syntheses, structures, magnetic and fluorescence properties of coordination polymers constructed with the reduced Schiff base carboxylic acid ligand

Using a reduced Schiff base carboxylic acid ligand 2-((pyridin-4-ylmethyl)amino)terephthalic acid (H2L), five new coordination polymers (CPs), namely, {[Mn2(L)2(H2O)]·DMF]}n (1), {[Cd(L)(H2O)2]}n (2), {[Cu(L)(H2O)3]·2H2O}n (3), {[Cu(L)(H2O)]}n (4), {[Eu2(L)3(H2O)3(H2O)0.5]·O}n (5) were obtained via different synthesis method and further characterized. Complex 1 is a three-dimensional (3D) framework with a (3, 8)-connected hex topology constructed by binuclear [Mn2N2O9] building unit. In complex 2, the adjacent Cd(II) centers are connected by L2‒ ligands using (κ2)-(κ2)-(κ1)-μ3 coordination pattern to form two-dimensional plane structure. In complex 3, the one-dimensional structures linked by hydrogen bonds (O4‒H7B···O7) to form a 2D supramolecular structure. 4 is a 3D structure and 5 belongs to (3, 5)-connected topology with point symbol of {48·62}. It is worth noting that complexes 1, 3 and 4 show the significant antiferromagnetic interactions indicated that they are potential magnetic materials. Remarkably, compared with H2L ligand, the maximum emission peaks of 2 exhibit varying degrees of blue-shifted, and further study for 2 finds that it can acts as luminescence sensor to selectively detect nitrobenzene (NB).

Development of a hierarchical microchannel heat sink with flow field reconstruction and low thermal resistance for high heat flux dissipation

With the development of microelectronics, power density continues to rise, which has put forward higher requirements for the thermal management. At present, the microchannel heat sinks have been investigated as an efficient way for heat dissipation for a long time. However, the optimization of microchannel heat sink is always concentrated on two-dimensional plane structure. In this paper, we proposed a hierarchical microchannel heat sink for heat transfer enhancement. Taking micro pin fin as an example, we designed three different hierarchical pin fins, and the model with the best performance is obtained through simulation under the Reynolds number from 1500 to 5500. The hierarchical heat sink shows better heat transfer performance than traditional heat sink, which is attributed to the flow field reconstruction with no significant increase in pressure drop. Typically, when the upper size (Wp1) of hierarchical pin fin increases to 375 μm, the maximum Nusselt number reaches 21 with the thermal performance factor up to 1.03 under the Reynolds number of 5500. Experimentally, three sizes of pin fins have been prepared and examined, and the results show that the heat loads exceeding 700 W/cm2 can be dissipated with the maximum temperature rise of 52 K, which is well matched with the simulation results. Anyway, the proposed in this work shows great potential in heat dissipation of electronics.

Study of vibration modes and strain distribution of a flow energy harvester in the wake region of different bluff bodies

This paper aims to analyze mode shapes and corresponding strain distribution in a two-dimensional plane structure exhibiting flow-induced vibration in the wake field of four different upstream bluff bodies such as cylinder, square, triangle, and D-shape. This research is important from the point of view of flow-induced piezoelectric energy harvesting; wherein, induced strain in the structure is directly related to the amount of energy generated. Mainly, all investigations are carried out at low Reynolds number ( Re = 200); however, to widen the scope of the work, other Reynolds numbers are also considered ( Re = 300, 500, and 750 ). The results obtained indicated that the plane structure vibrates in different mode shapes under different wake fields. The square section dominantly gives rise to the fundamental mode vibration, whereas, cylinder, D-shape, and triangular bluff body induce vibration in a mix of fundamental and higher bending modes. Analysis of the corresponding flow regime shows that the position of reattachment point of the downstream shear layer plays an important role in the realization of different vibration modes. The strain distribution under different cases revealed that the wake of a cylindrical bluff body produces highest peak strain, and D-shape bluff body results in highest cumulative strain. From the aspect of energy harvesting, a quantitative comparison of strain-induced and per second charge generation have indicated that for an equivalent flow condition, the D-shape will produce higher energy per unit time than the cases of a square, cylinder, and triangular cross-sections.

Facile construction of flower-like black phosphorus nanosheet@ZnIn2S4 composite with highly efficient catalytic performance in hydrogen production

To make persistent efforts at enhancing hydrogen evolution driven by solar energy, this work, for the first time, had introduced flower-like ZnIn2S4 coupled with black phosphorus (BP) as efficient photocatalyst for hydrogen evolution with photo-deposited Pt assisted under visible light irradiation. The hydrogen evolution efficiency of BP, ZnIn2S4, 0.5%BP/ZnIn2S4, 0.5%Pt/BP, 0.5%Pt/ZnIn2S4 and 0.5%Pt/0.5%BP/ZnIn2S4 photocatalysts were successively conducted and results showed that both BP and Pt played an important role in enhancing the photocatalytic hydrogen evolution rate. Therefore, the ternary 0.5%Pt/0.5%BP/ZnIn2S4 composite exhibited the strongest hydrogen production efficiency at 1278 μmol/g/h, about 10 times higher than that of pristine ZnIn2S4 (131 μmol/g/h) and represented a highly stable characteristic after suffering four recycles. The promoting hydrogen evolution of ternary photocatalyst could be ascribed to the unique bandgap and larger two-dimensional plane structure of BP, which provided abundant landing sites for the anchor of flower-like ZnIn2S4, thus leading to a well-inhibited recombination and efficient separation of photogenerated electrons and hole pairs between ZnIn2S4 and BP. The remarkable photocatalytic hydrogen evolution performance and prominent stability all indicated that 0.5%Pt/0.5%BP/ZnIn2S4 was a promising photocatalyst candidate for solar hydrogen production.

Synthesis, Structures, and Properties of Two Coordination Polymers with Chelating Carboxylic and Triazolyl Derivatives

Two coordination polymers, [Zn(Btec)0.5(H2L)]n (I) and [Cd0.5(Tp)0.5(H2L')(H2O)]n ∙ nH2O (II) (H2L = 3-(1H-pyrazol-4-yl)-5-(pyridin-2-yl)-1,2,4-triazole; H4Btec = 1,2,4,5-benzenetetracarboxylic acid; H2L' = 3-(1H-pyrazol-4-yl)-5-(pyridin-3-yl)-1,2,4-triazole; H2Tp = terephthalic acid), have been synthesized under hydrothermal conditions. The title compounds were structurally characterized by elemental analysis, single crystal X-ray diffraction analysis, infrared spectra. Compounds I and II crystallize in the orthorhombic and triclinic, space group Pbca and P¯1, respectively. Compound I displays a two-dimensional plane structure, those are connected by N···H···O hydrogen bonds to generate 3D frameworks. Compound II is constructed a 1D chain structure by Tp2− ligands, which are connected into 2D structure by the hydrogen bonds. In addition, the fluorescent property of I has been studied in the solid state at room temperature. The thermal analysis of I has also been investigated.

Artificial Tactile Sensor With Pin-type Module for Depth Profile and Surface Topography Detection

Haptic sensors based on piezoelectric sensor arrays with pin-type modules which have high responses and dynamic sensing capabilities are designed and studied for surface topography measurements. Unlike the human finger, most flexible tactile sensor designs do not detect the depth information of surfaces well, which change at the mm level despite the fact that they have a good sensitivity for pressure or force. To enhance the ability to detect depth information of the surfaces of objects, a piezoelectric sensor combining a pin-type module with excellent monitoring in the depth direction by spring is developed in this paper. Because spike types of piezoelectric signals do not match a specific surface topography directly, a signal processing method that reconstructs the surface topography is studied considering the piezoelectric working principle and spring dynamics. According to the sensor design, it can detect 3 mm depth changes with a two-dimensional plane structure at mm-level resolutions. The results show that the proposed sensor could measure various shapes and depth profiles precisely via a sliding motion, and the surface topography is reconstructed through highly accurate measurement results, similar to a human.

Highly thermally conductive layered polymer composite from solvent-exfoliated pristine graphene

Highly thermally conductive polymer composites are urgently required to resolve the heat dissipation issue of rapidly evolving electronic devices. Owing to two-dimensional plane structure and extremely high thermal conductivity, graphene is an ideal thermally conductive filler for polymer composites. In view of the increasing maturity of solvent exfoliation technique and its ability to produce high-quality graphene on a large scale at low cost, we aim to develop highly thermally conductive polymer composites from solvent-exfoliated, plane defect-free graphene, instead of oxidation-exfoliated, plane defect-rich graphene. Solvent-exfoliated pristine graphene/poly(vinylidene fluoride) composites with well-ordered layered structure are produced through a simple, scalable doctor-blading process. The combination of high-quality solvent-exfoliated pristine graphene and well-ordered layered microstructure forms high-efficiency, directional and dense pathways for phonon transport, and thus endows the polymer composites with high thermal conductivities (41.64 W/mK), surpassing the previously reported oxidation-exfoliated graphene-based polymer composites (2.1–19.5 W/mK). It provides a new route to fabricate highly thermally conductive composites from solvent-exfoliated pristine graphene.

An ultra-broadband metamaterial absorber based on the hybrid materials in the visible region

In this paper, an ultra-broadband metamaterial absorber is successfully designed in the visible region. The structure of the absorber is just obtained by the two-dimensional plane structure which rotate 90° along x-axis. Furthermore, the formation of the structure for the hybrid materials is based on the four U-shaped structure of the metal titanium is embedded in the semiconductor (indium antimonide). The simulated results show that the proposed metamaterial absorber can achieve an ultra-broadband absorption with greater than 90% from 252.2 to 822.3 THz, and the relative absorption bandwidth gets to 106.1%. Finally, the simulated electric field, surface current and power loss density distributions further illustrate the absorption mechanism of the metamaterial absorber. And we believe the metamaterial absorber will have many potential applications in energy harvesting and stealth devices.

First-Principles Investigation on the Interaction of Aun(n=2-9) Clusters with Ethanol

利用密度泛函理论研究了Aun（n=2-9）团簇吸附一个乙醇分子的结构和电子性质.研究结果表明：Aun（n=2-9）团簇的最稳定构型为二维平面结构,Au6团簇最稳定;吸附过程是通过金团簇上一个特定的金原子与乙醇分子中氧原子相互作用完成,形成了20种稳定构型;金原子的配位数对吸附作用影响明显;作为吸附主体的金团簇和被吸附的乙醇分子在吸附前后构型无明显变化,它们之间为弱相互作用.

An Interesting Complex: [Cd(l -trp) (d-trp)] n

A novel coordination polymer [Cd(l-trp) (d-trp)] n (where l-trp and d-trp are l-tryptophan and d-tryptophan or (S)-2-amino-3-(3-indolyl)propionic acid and (R)-2-amino-3-(3-indolyl)propionic acid) was prepared by a solvent-thermal method and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The compound(monoclinic space group P2(1)/c with a = 19.759(2) A, b = 5.2496(10) A, c = 9.7594(16) A, β = 97.2760(10)°, Z = 2) shows a two-dimensional plane structure. The crystallized coordination polymer has a centrosymmetric space group. Each Cd2+ ion coordinates with a pair of racemes, and the complex is a mesomer. Although l-trp was used, both l-trp and d-trp appear in the complex.

Preparation and characterization of graphite nanosheets from detonation technique

A mixture of natural graphite and HNO3 was used to form graphite intercalation compounds to prepare graphite nanosheets through destroying van der Waals forces between adjacent sheets with detonation technique. The average grain size, microstructure and morphology of the graphite nanosheets were characterized by XRD, TEM and SEM. The specific surface area was tested by nitrogen adsorption and the structure information was obtained from Raman spectra. The results indicated that the prepared graphite nanosheets have two-dimensional plane structure and nanosized thickness. The specific surface area of the nanosheets is 8 times higher than that of the raw graphite. It indicates that detonation method is convenient and effective in preparing graphite nanosheets.

Design, analysis and control of novel pressing and bending magnifying mechanism driven by giant magnetostrictive material

A novel pressing and bending flexible magnifying structure for micro-positioning system, which is driven by a giant magnetostrictive material based actuator, is introduced. Inspired by several other micro-displacement magnifying units, the mechanism is designed with a two-dimensional plane structure, which is both easy-manufacture and easy-using. It not only amplifies a micro displacement but also changes the direction of a translation motion by 90~. The parameters of the structure of the bended plate are optimized numerically by finite element analysis. It is observed that the hysteresis in a giant magnetostrictive material (GMM) actuator between the current or the magnetic field input and the output displacement changes with the frequencies of the input signals as well as the loads of the actuator. Two BP-neural networks are adopted to construct the inverse models of the upper and lower branches of the hysteresis loop, separately. And the two inverse models are selected by the input signals in real time control. Simulation results prove the correctness of the neural network based inverses in hysteresis compensations. An experiment setup of GMM based pressing and bending mechanism is developed. Experiments performed on the setup show the effectiveness of the inverse based compensation method for hysteresis with both main and minor loops.

Preparation of three terbium complexes with p-aminobenzoic acid and investigation of crystal structure influence on luminescence property

Three new rare earth p-aminobenzoic acid complexes, [Tb2L6(H2O)2]n (1), [Tb2L6(H2O)4]·2H2O (2) and [Tb(phen)2L2(H2O)2](phen)L·4H2O (3) (HL: p-aminobenzoic acid; phen: 1, 10-phenanthroline), with different structural forms are reported in this paper. Complex 1 is a polymolecule with a two-dimensional plane structure. Compound 2 is a binuclear molecule, and 3 appears to be a mononuclear complex. The fluorescence intensity, the fluorescence life-time and emission quantum yield of 2, which has two coordination water molecules, is better than those of 1, which has only one coordination water molecule. This is an unusual phenomenon for general fluorescent rare earth complexes. The fluorescence performance of 3 is the most unsatisfactory among the three complexes. Their crystal structures show that the coordination mode of the ligand is an important factor influencing the luminescence properties of a fluorescent rare earth complex.

Preparation of porphyrin mono- and multi-layer films based on the polymer Langmuir–Blodgett method

Polymer mono- and multilayer films containing 5,10,15,20-tetraphenylporphyrin (TPP) moieties in various amounts were prepared by the conventional Langmuir–Blodgett (LB) technique using amphiphilic copolymers based on poly(isobutyl methacrylate). The copolymers showed similar surface pressure (π)–area ( A) isotherms even for the high TPP contents, indicating that the TPP moieties are located out-of-plane of the monolayer on the air/water interface. The deposition onto solid substrates allowed one to fabricate multilayer films, in which the TPP moieties were incorporated into the polymer ultrathin films of only approximately 1 nm in thickness. The absorption dichroism revealed that the TPP moieties took a parallel orientation with a uniform distribution in the two-dimensional plane structure.