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In this work, different doping strategies are adopted to improve the photocatalytic activity of KTaO3 (KT) by hybrid functional theory. The La and W monodoped KTs are n-type semiconductors and the photocatalytic performance of Ti, Mo, Cr, N, La–Bi, La–Cr, W–N, Cr–N, Cr–Ti doped KTs are limited by either wide bandgaps or the appeared local unoccupied impurity states. The Bi, C monodoped and La–C, Mo–N, Mo–Ti, W–Ti codoped KTs possess suitable bandgaps of 2.12, 2.06, 1.39, 2.66, 2.66, and 2.61 eV for absorbing visible light without the introduction of localized unoccupied states. The band edge alignments suggest that Mo–N and W–Ti codoped KTs possess the ability for spontaneous overall water-splitting, Bi and Mo–Ti doped KTs can only spontaneously produce oxygen, and C doped KTs only spontaneously generate hydrogen. While La–C doped KT is thermodynamically unfeasible to generating both hydrogen and oxygen. Thus, Mo–N and W–Ti codoped KTs are promising photocatalysts for overall water-splitting, and Bi, C, and Mo–Ti doped KTs are considered for Z-scheme photocatalysis.

The effect of the γ-ray total dose radiation on the energy storage density (ESD) and the phase transition of antiferroelectric-like (AFE-like) Al-doped HfO2 (HfAlO) thin films was investigated. The ESD property and wake-up behavior of the phase transition during the field cycling of the AFE-like HfAlO thin films were quantified before and after the radiation. The efficiency of the AFE-like thin films for energy storage slightly decreases as the total dose increases from 200 krad (Si) to 5 Mrad (Si), which is attributed to the radiation-induced trapped defects at the interfaces of HfAlO/TiN. Both the J–E, C–V, and er–f characteristics of the AFE-like HfAlO thin films were also measured before and after the radiation at the same electrodes. These results further confirm that the ferroelectricity of the thin films can be reduced due to the radiation oxide trapped defects. It is worth noting that an enhanced wake-up behavior of the AFE-like HfAlO thin films can be observed after the radiation, which indicates that the transition from the antiferroelectric phase to the ferroelectric phase could be accelerated by the increased radiation-induced defects.

Based on hybrid density functional calculations, the geometrical and electronic structures of a two-dimensional (2D) CdO/CdS heterostructure (HT) formed by a CdO monolayer (ML) and a CdS ML are investigated. The formation of the CdO/CdS HT is exothermic, and the CdO/CdS HT shows excellent ability for visible light absorption. The CdO/CdS HT with a rotation angle of 0° possesses the characteristics of type-II band alignment and strong built-in electric field across the interface, which boost the photogenerated carrier separation. Besides, the band edge positions of the CdO/CdS HT of 0° are energetically favorable for overall water-splitting processes with the pH scope of 0-3.6. Therefore, the CdO/CdS HT is a promising photocatalyst to split water.

The $\gamma $ -ray total dose radiation effects on ferroelectric Al-doped HfO2 (HfAlO) thin films with an n-type Si substrate were studied. The $I$ - $V$ , $P$ - $V$ , $C$ - $V$ and fatigue characteristics of the HfAlO-based Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structure were analyzed with the increasing total dose from 0 to 1 Mrad (Si). The remnant polarization ( $P_{\mathrm {r}}$ ) values, the capacitance ( $C$ ) values and the switching voltage ( $V_{\mathrm {c}}$ ) of this MFIS gate structure decreased with the increasing total dose. A TCAD model of Metal/HfAlO/SiO2/Si (MFIS) was proposed to explain the degradation mechanism of ferroelectric properties of the MFIS structure. We find that the new interface defects caused by radiation can reduce the electric field strength with the increasing total dose, which can significantly influence the irradiation properties of the HfAlO/SiO2/n-Si gate structure. These results provide the basis to applications for the HfO2-based devices in radiation working environment.

Many medical images domains suffer from inherent ambiguities. A feasible approach to resolve the ambiguity of lung nodule in the segmentation task is to learn a distribution over segmentations based on a given 2D lung nodule image. Whereas lung nodule with 3D structure contains dense 3D spatial information, which is obviously helpful for resolving the ambiguity of lung nodule, but so far no one has studied it. To this end we propose a probabilistic generative segmentation model consisting of a V-Net and a conditional variational autoencoder. The proposed model obtains the 3D spatial information of lung nodule with V-Net to learn a density model over segmentations. It is capable of efficiently producing multiple plausible semantic lung nodule segmentation hypotheses to assist radiologists in making further diagnosis to resolve the present ambiguity. We evaluate our method on publicly available LIDC-IDRI dataset and achieves a new state-of-the-art result with 0.231±0.005 in $D_{GED}^2$. This result demonstrates the effectiveness and importance of leveraging the 3D spatial information of lung nodule for such problems. Code is available at: https://github.com/jiangjiangxiaolong/PV-Net.

Because of the influence of hydrogen and the stress corrosion cracking, the damage of metal is quite frequent. It leads to dangerous failures, the loss of property as well as large compensational payments for insurance companies. However, the issue of the precise role of hydrogen in the process is unclear and the mechanism is not available. Based on the binding energy analysis, it was found that H prefers octahedral-like positions for γ-Fe, and could enhance the stability of structure with dissolving into γ-Fe. The higher the concentration of H, the much more remarkable the observation is. Therefore, H is easily soluble in γ-Fe. Under the applied tensile stress, γ-Fe and H doped γ-Fe undergo the stages of elastic and plastic deformations. Meanwhile, H induces γ-Fe phase transition.This process starts from the atomic layer adjacent to H, then gradually extends far. As a consequence, the intergranular embrittlement and cracking happened.

The metallic tortuous hollow ring array in the metallic film is proposed to enhance the modulation efficiency of the graphene based terahertz (THz) amplitude modulation. In the tortuous ring configuration, multimode resonant is excited to enhance the interaction between the THz wave and the graphene. With the change of the chemical potential of the graphene layer, the resonant frequencies are shift and the transmission peaks are tuned. It is enhanced more than 9 times for the amplitude modulation depth of the THz transmission and a maximum modulation efficiency of 74 dB/eV is obtained in the tortuous ring array based modulator. The enhancement of the modulation efficiency will decrease of the applied modulation voltage and will help to the energy saving and device lifetime prolonging.

Employing the nonequilibrium Green’s function technique, electron transport characteristics through a laterally coupled triple-quantum-dot chain are investigated. The conductance versus electron energy is numerically calculated. Two anti-resonance points change into two anti-resonance bands with increasing the size of triple-quantum-dot chain. The widths of two anti-resonance bands are the same and can be regulated via adjusting the inter-dot tunneling coupling strength in the main chain or its attachment. Spin-polarized window emerges due to Zeeman splitting as an external magnetic flux is introduced. Our studies demonstrate that the system can be used as a quantum switch or an efficient spin filtering.

We have calculated and discussed the electronic and optical properties of two-dimensional (2D) CdS/g-C6N6 heterostructures by using hybrid density functional of HSE06. The CdS and g-C6N6 can form CdS/g-C6N6 heterostructures through weak van der Waals (vdW) interactions. The CdS/g-C6N6 composites are indirect bandgap semiconductors and type-II heterostructures. The visible light absorbtion of CdS/g-C6N6 composites is obviously improved, and the band alignment is beneficial for spontaneous water redox reactions. Furthermore, the electrons migrating from CdS layer to g-C6N6 leads to the built-in electric field formation, which promotes the effective separation of photogenerated carriers. These factors imply CdS/g-C6N6 composites are promising visible light water-splitting photocatalysts.

In the present work, a systematic analysis of the microscopic plastic deformation mechanism and mechanical properties of interstitial impurities (H, O, N, S, and P) and Ni doped, or not doped, with Cr, was conducted based on generalized stacking fault energy curves generated via first-principles calculations. Focus has been put on the effects of Cr on plastic deformation for Ni doped interstitial impurities, upon the GPFE curve, with the aim to investigate the effects of Cr on the deformation mode and mechanical properties for doped Ni systems. It is found that a solid solution of Cr caused the tendency of partial dislocation in Ni. The evaluation of the Rice criterion reveals that Cr tends to decrease the ductility in Ni, and it cannot reverse interstitial H promoting the probability of cleavage fracture in Ni, while increases the ductility of O, P and S doped Ni, particular in O doped Ni, due to increasing the value of ductility D remarkably, so possibly changes the tendency of cleavage fracture. Besides, the solid solution of Cr is beneficial in promoting the dissociation of dislocation into fragments more easily in Ni, and enhances dislocation nucleation, while O, N, and S impurities have a slower rate of partial dislocation emission in Ni when interacting with Cr. Furthermore, Cr promotes the probability of twinning in Ni, and probably switches the deformation mechanism of H doped Ni from dislocation mediated slipping to twinning. Our study provides important insights toward the understanding and control of dislocation dynamics in doped Ni.

It still remains a great challenge to develop a high-performance anode for sodium ion batteries. In this work, carbon-coated CoP3(CoP3@C) nanocomposites have been obtained by a high energy mechanical milling and used as an anode of sodium ion battery for the first time, showing a larger discharge capacity, longer cycling life and better rate capability as compared to plain CoP3. The superior performance is not only originated from significantly enhanced diffusion kinetics associating with the improvement of electron conductivity and volume change based on the presence of carbon layer, but also attributed to the partially pseudocapacitive behaviors of the redox reaction to construct a rapid electron transport pathway. In addition, the XRD and TEM analysis reveal that the Na-storage mechanism of the CoP3@C anode involves a conversion reaction from CoP3 to Na3P and metallic Co at the initial discharge and charge state. This study also provides a significant strategy to design special hybrid materials with excellent sodium storage capability for meeting the demand of large-scale energy storage systems.

Effect of grain boundaries (GBs) on elastic shock wave in graphene is investigated by molecular dynamics simulations. Bicrystal graphenes with symmetrical GB are shocked along directions perpendicular and parallel to GB. For perpendicular shock loadings, double elastic shock waves emerge in form of quasilongitudinal (QL) and quasitransverse (QT) waves, since the loading direction is neither zigzag nor armchair. GB attenuates the QL wave and gives rise to new QT waves propagating into grains. Transverse particle motion in the elastic shocks can induce small lattice rotations and different oriented regions, whose number increases upon the passage of waves through GB. Upon shock loadings along GB, transverse particle motions of opposite direction generate in the two grains, and change the pressure distribution right behind wavefront, and then result in deviation of shock wave from planar loading or “V” shaped wavefront turning at GB. The above phenomena are attributed to the turn of grain orientation at GB and transverse particle motions induced by lattice symmetry reduction upon shock compression.

Metal oxides possess enormous potentials in the electrochemical storage fields on account of their high theoretical capacity and abundant natural resources. Nevertheless, the inferior electric conductivity, severe volume variation accompanied with structural collapse result in the unsatisfied cycling lifespan and rate performance upon cycling. Herein, a hierarchical hydrangea-like configuration with double defense layers of carbon and MoSe2 nanosheets modified on the surface of Fe3O4 nanocubes is constructed and further examined as an anode for sodium-ion batteries, manifesting the significant Na+-storage lifespan over 5700 cycles with a competitive reversible capacity of 272.2 mAh g−1 at a rate up to 5.0 A g−1 and superb kinetically pseudocapacitive behaviors of 88.6% and 96.3% at 0.2 and 2.0 mV s−1, respectively. This work could offer a potential strategy to design other hierarchical metal oxides architecture toward high reversibility and long cyclability of metal-ion batteries.

Photocatalytic water-splitting for hydrogen generation is a promising way to solve the energy crisis, yet the design of efficient photocatalysts is still a challenge. By utilization of first principles calculations, we predict the photocatalytic properties of monolayer boron phosphide (BP) based BP/XY

The shock deformation and spallation of Cu bicrystals with (1 1 1) twist grain boundary (GB) of different misorientation angles are investigated by using molecular dynamics simulations. The selected GBs include low angle (LAGB), near twin (NTGB) and intermediate angle (IAGB) twist GBs, and the shock direction is along the GB normal. It is demonstrated that the bicrystals are of lower Hugoniot elastic limit than single crystal, as the twist GBs provide dislocation sources for deformation. At the shock compression stage, GB plasticity at the LAGBs and NTGBs is initiated via reaction and dissociation of GB dislocations, and can be triggered by elastic shock wave more readily than that at the IAGBs, on which dislocation emission is homogeneous and irrelevant to initial GB dislocations. At the tension stage, the incipient spall for different twist GBs occurs at an identical shock strength, but is of different details in dislocation and void evolutions. With varying shock strength and misorientation angle, spall strength of the Cu bicrystals depends on whether GB plasticity is produced at the compression stage, and the values are consistent with that of Cu single crystal under similar shock loading conditions.

Engineering suitable tin selenide (SnSe) anode for sodium ion batteries (SIBs) with both excellent cycling durability and remarkable rate capability has received enormous attention. The effective regulation of morphology and size has been shown to promote electrochemical performance. The irregular shape and micron size of obtained SnSe by conventional construction methods (high energy ball milling) is detrimental to the anode performance. Herein, SnSe quantum-dots (E-SnSe) and SnSe nanoparticles (B-SnSe) are synthesized by means of a feasible electrospinning technique together with subsequent high-temperature selenylation and high energy ball milling, respectively, and both are examined as anode materials for SIBs. As compared to B-SnSe electrode, the E-SnSe electrode delivers a larger discharge capacity of 268 mAh g−1 after 750 cycles at 2 A g−1 and more remarkable cycling durability over 1500 cycles even at much higher rate of 5 A g−1, which is the best cycling stability reported so far for SnSe-based anodes. The significantly enhanced performance is attributed to unique three-dimensional (3D) conductive carbon network structure of E-SnSe, which could boost rapid electron/sodium ion transport with the remarkable contribution of pseudocapacitance and dramatically improve the structure evolution of SnSe resulted from the conversion and alloying process. Furthermore, the assembled Na3V2(PO4)3@C//E-SnSe full cell shows an output voltage of above 2.0 V, ultralong cycle life of 1500 cycles with a high reversible discharge capacity of about 100 mAh g−1 at 1 A g−1 and superior rate capability with 86.4% capacity retention after 35 cycles, showing the potential application prospects in a large scale energy storage field.

Photocatalytic water-splitting for hydrogen generation is a promising way to solve the energy crisis, yet the design of efficient photocatalysts is still a challenge. By utilization of first principles calculations, we predict the photocatalytic properties of monolayer boron phosphide (BP) based BP/XY2 (X = Mo, W; Y = S, Se) composites of different rotated configurations. Our results suggest that the BP/XY2 composites can be stably formed, and the narrowed bandgaps ensure these composites are suitable for absorbing visible light. The bandgaps and band edge positions are slightly affected by the rotation angles. The BP/MoS2, BP/MoSe2, and BP/WSe2 are type II heterostructures. Furthermore, the transferred charge from BP to XY2 layers leads to the formation of electric fields, which efficiently separate the photoinduced carriers. The band alignments of BP/MoS2, BP/MoS2, BP/MoSe2, and BP/WSe2 satisfy the requirements of overall water-splitting within the pH scope of 3.6-7.9, 6.8-7.9, 4.0-8.0, and 8.7-8.8. This work will provide valuable insight for designing efficient water-splitting photocatalysts.

The structural, electronic, and optical properties of two-dimensional (2D) CdO/g-C6N6 nanocomposite are studied through hybrid density functional. The results show that the CdO monolayer can contact with g-C6N6 through van der Waals interaction to form the CdO/g-C6N6 heterostructure. A narrower bandgap value is found for CdO/g-C6N6, compared to both CdO monolayer and g-C6N6 monolayer, which is conductive to the absorption of visible-light. Furthermore, the CdO/g-C6N6 composite shows appropriate band alignment and efficient charge separation. These factors indicate that the CdO/g-C6N6 composite is a promising visible-light water-splitting photocatalyst.