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1.
以过渡金属为催化衬底的化学气相沉积法(Chemical Vapor Deposition,CVD)已经可以制备与机械剥离样品相媲美的石墨烯,是实现石墨烯工业应用的关键技术之一。原子尺度理论研究能够帮助我们深刻理解石墨烯生长机理,为实验现象提供合理的解释,并有可能成为将来实验设计的理论指导。本文从理论计算的角度,总结了各种金属衬底在石墨烯CVD生长过程中的各种作用与相应的机理,包括在催化碳源裂解、降低石墨烯成核密度等,催化加快石墨烯快速生长,修复石墨烯生长过程中产生的缺陷,控制外延生长石墨烯的晶格取向,以及在降温过程中石墨烯褶皱与金属表面台阶束的形成过程等。在本文最后,我们对当前石墨烯生长领域中亟需解决的理论问题进行了深入探讨与展望。 相似文献
2.
Cobalt oxide (Co3O4) modified anatase titanium dioxide nanotubes (ATNTs) have been investigated for the electrochemical sensing of hydrogen peroxide (H2O2). ATNTs have been synthesized by a two-step anodization process. ATNTs were then modified with Co3O4 employing chemical bath deposition method. The structure and morphology of ATNTs and their modification with Co3O4 has been confirmed by X-ray diffraction by scanning electron microscopy. H2O2 sensing has been studied in 0.1 M PBS solution, by cyclic voltammetry and amperometry. Variation in the peak positions and current densities was observed with addition of H2O2 for Co3O4 modified ATNTs. Sensitivity and limit of detection improved with modification of ATNTs with Co3O4 with precursor concentration up to 0.8 M. However, at higher precursor concentrations sensitivity and limit of detection toward H2O2 deteriorated. Co3O4 Modified ATNTS using 0.8 M precursor concentration are comparatively more suitable for H2O2 sensing applications due to the optimum formation of Co3O4/ATNTs heterojunctions. 相似文献
3.
By using angle resolved photoemission spectroscopy, we investigate the electronic structures of Pt-skin layer of Pt–Co and Pt–Ni alloys with CO molecules on the surface. Measured Fermi surface maps and band dispersions reflect the signatures of chemical bonding between Pt-skin layer and CO molecules. Furthermore, the degree of chemical bonding strength of CO molecules, estimated from the energy shift of the participating bands, is found to be reduced on both Pt bimetallic alloys. Our results show how the surface band structure of Pt bimetallic alloys is modified with molecular orbitals of CO molecules on the surface, revealing the important role of the electronic structure in the determination of chemical properties of bimetallic alloys. 相似文献
4.
Jie Pan Yan Bao Hao Wang Fucong Lyu Lu Liu Chong Wang Xinxue Tang Jian Lu Yang Yang Li 《Particle & Particle Systems Characterization》2021,38(10):2100094
The high-entropy materials have raised much attention in recent years due to their extraordinary performances in mechanical, catalysis, energy storage fields. Herein, a new type of high-entropy hydroxides (e.g., NiFeCoMnAl(OH)x) that are amorphous and capable of broad solar absorption is reported. A facile one-pot co-precipitation method is employed to synthesize these amorphous high-entropy hydroxides (a-HEHOs) under ambient conditions. The a-HEHOs thus obtained display widely tunable bandgap (e.g., from 2.6 to 1.1 eV) due to their high-entropy and amorphous characteristics, enabling efficient light absorbance and photothermal conversion in the solar regime. Further solar water evaporation measurements show that the a-HEHOs delivered a considerable energy conversion efficiency of 55%, comparable to black titanium oxides that are synthesized using more complex and expensive methods. 相似文献
5.
The localized electrostatic structures with dissipation due to ion-neutral collisions in a symmetric warm pair-ion plasma in the presence of non-Maxwellian population of electrons are studied. The analytical model for ion dynamics is based on fluid equations and the evolution equation is derived by using the reductive perturbation scheme in the form of a damped Korteweg-de Vries equation. The parameter regime relevant to space-based observations and laboratory plasmas is considered and time evolution of the propagating ion-acoustic soliton is discussed. The energetic-particles-driven properties of soliton for various spectral indices, dissipation, ion temperature, and density are illustrated with comparison to the thermal mode for Boltzmann distribution of electrons. 相似文献
6.
Tong Liu Guiting Liu Jianhua Zhang Zhangfan Ding Yike Li Krishna Sigdel Xiaoyi Wang Huixu Xie 《中国化学快报》2022,33(4):1880-1884
Nowadays, there are still many challenges to skin regeneration. As a new type of skin substitute, hydrogel has emerging gradually with its excellent properties. However, it is still a challenge to combine with biological active agents to facilitate skin regeneration. Under the circumstance, we synthesized argininebased poly(ester amide)(Arg-PEA) and hyaluronic acid(HA-MA), and combined them into new hybrid hydrogels via photo-crosslinking. We found that the internal structure and physicochemical... 相似文献
7.
Jian-Kun Sun Linlin Zhang Liang Yue Tang Tang Wen-Jie Jiang Yun Zhang Zhenxiao Pan Xinhua Zhong Jin-Song Hu Li-Jun Wan 《中国科学:化学(英文版)》2018,61(10):1338-1344
Developing efficient counter electrodes (CEs) and quantum dots made of earth-abundant and non-toxic elements is essential but still challenging for quantum dot-sensitized solar cells (QDSSCs). Here, we report a facile strategy to prepare self-supported and robust CoS2 and NiS nanocrystals-assembled nanosheets directly grown on carbon paper (MSx NS@CP) as efficient counter electrodes for QDSSCs. Such CEs integrate the merits of fast electron transfer from interconnected conductive scaffold, efficient mass transfer from hierarchically vertical nanosheet on 3D open substrate, as well as abundant highly active catalytic sites from metal sulphide nanocrystal units. As a result, QDDSCs based on such CoS2 NS@CP and NiS NS@CP CEs achieve a PCE of 8.88% and 7.53%, respectively. The detailed analyses suggest that CoS2 NS@CP has the highest catalytic activity and shows the lowest charger transfer resistance, leading to the highest PCE. These findings may inspire the design and exploration of other self-supported efficient CEs by integrating highly active catalysts onto 3D conductive networks for efficient QDSSCs. 相似文献
8.
Using first principles density functional theory, we predict a monolayer B2Si structure with space group Pmm2 in the present work. This structure is confirmed to be dynamically stable. Based on the plane wave pseudopotential approach, the charge density, electron localization function, density of states, energy band, phonon property and thermal conductivity of Pmm2-B2Si are systematically studied. It is interesting that the sp2 hybridization and coordination bond of Si are found in Pmm2-B2Si, which is the most important factor for its structural stability. The density of states and energy band analysis reveals that Pmm2-B2Si is metallic because of the partial occupied Si 3pz and B 2pz states. Moreover, the acoustic-optical coupling is important for phonon transport in Pmm2-B2Si, and the contribution of optical modes to the lattice thermal conductivity along the [100] and [010] directions is 13% and 12%, respectively. This study gives a fundamental understanding of the structural, electronic and phonon properties in Pmm2-B2Si. 相似文献
9.
The behaviors of ferromagnetic transition metals of the first period: Fe, Co and Ni are examined within density functional theory calculations in two dimensional carbon extended networks using model structure LiC6. Around geometry optimized structures, the energy-volume equations of states considering non magnetic and spin polarized configurations established ferromagnetic ground states with magnetizations –reduced with respect to the metals’– of 2 μB for FeC6 and 1 μB for CoC6 while no magnetic solution could be identified for NiC6. In the D6h point group of the P6/mmm space group lm decomposition of the d states results with increasing energy into doublet state E1g with d(x2-y2) and d(xy); singlet state A1g d(z2) and doublet state E2g d(xz) and d(yz) lying on EF and responsible of the onset of magnetic moments. This was mirrored via molecular orbital approach with a construct of Fe embedded between two extended carbon networks thus validating the model structure proposed for TC6 compounds. The 100% polarization in one spin channel allows proposing potential uses in spintronics applications. 相似文献
10.
Ying Yu Hao Xing Zhicong Zhou Junkai Liu Herman H-YSung Ian D.Williams Jonathan E.Halpert Zheng Zhao Ben Zhong Tang 《中国科学:化学(英文版)》2022,65(1):135-144
Molecular interactions are crucial in diverse fields of protein folding,material science,nanotechnology,and life origins.Although mounting experimental research controls luminescent behavior by adjusting molecular interactions in light-emitting materials,it remains elusive to correlate microscopic molecular interactions with macroscopic luminescent behavior directly.Here,we synthesized three red luminogens with subtle structural variation and investigated the influence of molecular interactions on their luminescent behavior in solution and aggregate states.Our results indicate that strongπ-πand D-A interactions in both dilute solution(between luminogen and solvent molecules)and aggregate(between luminogens)states cause the redshift in emission,while weak interactions(e.g.,Van der Waals,C–H…π,and C–H…F interactions)enhance the quantum yield.This work provides a thoughtful investigation into the complicated influence of various molecular interactions on luminescent behavior. 相似文献