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Carbonaceous materials are considered strong candidates as anode materials for sodium‐ion batteries (SIBs), which are expected to play an indispensable role in the carbon‐neutral era. Herein, novel braided porous carbon fibres (BPCFs) are prepared using the chemical vapour deposition (CVD) method. The BPCFs possess interwoven porous structures and abundant vacancies. The growth mechanism of the BPCFs can be attributed to the polycrystalline transformation of the nanoporous copper catalyst in the early stage of CVD process. Density functional theory calculations suggest that the Na+ adsorption energies of the mono‐vacancy edges of the BPCFs (−1.22 and −1.09 eV) are lower than that of an ideal graphene layer (−0.68 eV), clarifying in detail the adsorption‐dominated sodium storage mechanism. Hence, the BPCFs as an anode material present an outstanding discharge capacity of 401 mAh g−1 at 0.1 A g−1 after 500 cycles. Remarkably, this BPCFs anode, under high‐mass‐loading of 5 mg cm−2, shows excellent long‐term cycling ability with a reversible capacity of 201 mAh g−1 at 10 A g−1 over 1000 cycles. This study provided a novel strategy for the development of high‐performance carbonaceous materials for SIBs. [ABSTRACT FROM AUTHOR]

Hierarchical hollow CoP and carbon composites were obtained through a facile synthetic method, where carbonization and phosphorization of the precursor were completed within one single step. The composites are composed of hollow CoP@C spheres, which are further made up of CoP nanoparticles with a thin outer carbon layer. Electrochemical performances of the prepared CoP@C composites as anodes for sodium and potassium storage were evaluated and compared. In situ TEM, in situ synchrotron XRD, and DFT calculations were conducted to study the structural evolution and the interaction between Na/K and CoP during cycling processes. Benefiting from the synergistic effect of conductive carbon layer and hierarchical hollow structure, the as‐prepared CoP@C composites demonstrate superior sodium and potassium storage capability as anode materials for rechargeable batteries. [ABSTRACT FROM AUTHOR]

The microstructure and defects of as-grown and annealed ZnO/Si thin films were investigated by high-resolution transmission electron microscopy (HRTEM). The cross-sectional bright-field TEM images showed that the ZnO thin films consisted of columnar grains. The selected-area electron diffraction pattern showed that the ZnO/Si thin film were c-axis oriented and the deviation angle along the ZnO (0001) direction with respect to the growth direction was no more than 5°. The grain boundaries can be classified into three types: low-angle boundaries, boundaries near a 30 deg angle with (1010) facet structures and large-angle boundaries. In addition to grain boundary, the as-grown and annealing processing defects were also investigated by HRTEM. The crystal quality of the ZnO/Si thin films can be improved by annealing at 600 °C. However, at too high an annealing temperature of 800 °C, the newly produced processing defects such as three layer stacking fault and double stacking fault were formed. The research was useful for us to find optimal growth conditions to improve ZnO/Si thin film quality. [ABSTRACT FROM AUTHOR]

In this work, a comparative study of thermally reduced graphite oxide (rGO) materials prepared by thermal exfoliation and reduction of graphite oxide (GO) at the temperature of 300 °C and 600 °C under different atmospheres (air, N2, Ar, vacuum and H2) was investigated through kinds of characterizations. The evaluation of chemical structure and quality of the rGOs by these various atmospheres is of high importance and is attempted side‐by‐side for the first time in this paper. The order of C/O ratio of rGOs obtained at 600 °C is that HH‐rGO>HV‐rGO>HAr‐rGO≈HN‐rGO>HA‐rGO, whereas the effect of atmospheres on the rGOs obtained at 300 °C is not obvious. HH‐rGO possesses better restoration of π‐conjugated structure and the increased average size of sp2 carbon domains compared with other rGOs. rGOs with higher reduction degree result in the aggregation of rGO nanosheets and closer to graphite structure. TGA results proved the order of thermal stability is that HH‐rGO>HV‐rGO>HAr‐rGO≈HN‐rGO>HA‐rGO. Additionally, HH‐rGO could be easily exfoliated to few‐layer nanosheets compared with others according to the AFM measurement. We believe that the findings will deepen our understanding of graphene obtained via thermal exfoliation and reduction method. In this work, the effect of atmospheres and temperature on the chemical structure and quality of the rGOs was investigated. The order of C/O ratio and the order of thermal stability of rGOs were obtained through XPS and TGA results, respectively. The defect level of of rGOs (300 °C) under different atmospheres is similar. The ID/IG value for HH‐rGO (0.90) obviously decreased. Additionally, HH‐rGO could be easily exfoliated to few‐layer nanosheets compared with others according to the AFM measurements. [ABSTRACT FROM AUTHOR]

Presents a study on the calculation of the critical layer thickness strain in Si1-xGe/Si strained-layer heterostructures. Heterostuctures and superlattices of Si1-Gex/Si; Theoretical model and calculation used to carry out the study; How the critical layer thickness is reduced.

How a heavily charged metal nanocrystal, and further a dual-nanocrystals system behavior with continuous electron charging? This refers to the electric dynamics in charged particles as well as the crystal growth for real metal particles, but it is still opening in experimental observations and interpretations. To this end, we performed an in-situ electron-beam irradiation study using transmission electron microscopy (TEM) on the Au nanocrystals that freely stand on the nitride boron nanotube (BNNT). Au nanocrystalline particles with sizes of 2–4 nm were prepared by a well-controlled sputtering method to stand on the BNNT surface without chemical bonding interactions. Au nanoparticles presented the surface atomic disorder, diffusion phenomena with continuous electron-beam irradiation, and further, the long-range motion that contains mainly the three stages: charging, activation, and adjacence, which are followed by final crystal growth. Firstly, the growth process undergoes the lattice diffusion and subsequently the surface-dominated diffusion mechanism. These abnormal phenomena and observations, which are fundamentally distinct from classic cases and previous reports, are mainly due to the overcharging of Au nanoparticle that produces a surface activation state in terms of high-energy plasma. This work therefore brings about new observations for both a single and dual-nanocrystals system, as well as new insights in understanding the resulting dynamics behaviors. [ABSTRACT FROM AUTHOR]

Highly c-axis oriented LiNbO3 thin film has been deposited on the SiO2/Si substrate by KrF excimer pulsed laser deposition (PLD) technique under optimized conditions of 30-Pa oxygen pressure and 600 °C substrate temperature. The amorphous SiO2 buffer layer was coated on the Si (001) wafer by thermal oxidation in situ. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements confirm that the film shows superior crystalline quality and highly c-axis oriented texture. Neither the Li-enriched LiNbO3 target nor a biased electric field was applied during the deposition. [Copyright &y& Elsevier]

Artificial vision is crucial for most artificial intelligence applications. Conventional artificial visual systems have been facing challenges in terms of real-time information processing due to the physical separation of sensors, memories, and processors, which results in the production of a large amount of redundant data as well as the data conversion and transfer between these three components consuming most of the time and energy. Emergent optoelectronic memristors with the ability to realize integrated sensing-computing-memory (ISCM) are key candidates for solving such challenges and therefore attract increasing attention. At present, the memristive ISCM devices can only perform primary-level computing with external light signals due to the fact that only monotonic increase of memconductance upon light irradiation is achieved in most of these devices. Here, we propose an all-optically controlled memristive ISCM device based on a simple structure of Au/ZnO/Pt with the ZnO thin film sputtered at pure Ar atmosphere. This device can perform advanced computing tasks such as nonvolatile neuromorphic computing and complete Boolean logic functions only by light irradiation, owing to its ability to reversibly tune the memconductance with light. Moreover, the device shows excellent operation stability ascribed to a purely electronic memconductance tuning mechanism. Hence, this study is an important step towards the next generation of artificial visual systems., Competing Interests: The authors declare that they have no conflicts of interest in this work., (© 2022 The Authors. Publishing Services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.)

Hierarchical hollow CoP and carbon composites were obtained through a facile synthetic method, where carbonization and phosphorization of the precursor were completed within one single step. The composites are composed of hollow CoP@C spheres, which are further made up of CoP nanoparticles with a thin outer carbon layer. Electrochemical performances of the prepared CoP@C composites as anodes for sodium and potassium storage were evaluated and compared. In situ TEM, in situ synchrotron XRD, and DFT calculations were conducted to study the structural evolution and the interaction between Na/K and CoP during cycling processes. Benefiting from the synergistic effect of conductive carbon layer and hierarchical hollow structure, the as-prepared CoP@C composites demonstrate superior sodium and potassium storage capability as anode materials for rechargeable batteries., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new conductive carbon hybrid combining both reduced graphene nanoscrolls and carbon nanotubes (rGNSs-CNTs) is prepared, and used to host Fe 3 O 4 nanoparticles through an in situ synthesis method. As an anode material for LIBs, the obtained Fe 3 O 4 @rGNSs-CNTs shows good electrochemical performance. At a current density of 0.1 A g -1 , the anode material shows a high reversible capacity of 1232.9 mAh g -1 after 100 cycles. Even at a current density of 1 A g -1 , it still achieves a high reversible capacity of 812.3 mAh g -1 after 200 cycles. Comparing with bare Fe 3 O 4 and Fe 3 O 4 /rGO composite anode materials without nanoscroll structure, Fe 3 O 4 @rGNSs-CNTs shows much better rate capability with a reversible capacity of 605.0 and 500.0 mAh g -1 at 3 and 5 A g -1 , respectively. The excellent electrochemical performance of the Fe 3 O 4 @rGNSs-CNTs anode material can be ascribed to the hybrid structure of rGNSs-CNTs, and their strong interaction with Fe 3 O 4 nanoparticles, which on one hand provides more pathways for lithium ions and electrons, on the other hand effectively relieves the volume change of Fe 3 O 4 during the charge-discharge process.

The electrical, optical and other important properties of colloidal nanocrystals are determined mainly by the crystals' chemical composition, size and shape. The introduction of specific dopants is a general approach of modifying the properties of such nanocrystals in well-controlled ways. Here we show that in addition to altering the atomic composition of the nanocrystals the introduction of specific dopants can also lead to dramatic changes in morphology. The creation of Mg-doped ZnO nanocrystals provides an excellent example of this procedure; depending on the molar ratio of dopant precursor in the reagents, doped nanocrystals with well-defined shapes, from tetrapods to ultrathin nanowires, which exhibit tunable optoelectronic properties, are obtained for the first time. We find that the Mg dopants play an important role in the primary growth stage, resulting in initial growth seeds having diverse crystallographic structures, which are critical for the generation of doped nanocrystals with different shapes. We demonstrate that this "greener" synthetic scheme can be extended to other dopant systems and provides an attractive and effective strategy for fabricating doped ZnO nanocrystals with interesting compositional and spatial complexity.