Abstract
Vapor transport method has been successfully used to synthesize high quality VO
2
thin films on SiO
2
/Si substrate using V
2
O
5
as a precursor in an inert-gas environment. The ...morphological and structural evolutions of the intermediate phases during the nucleation and growth processes were investigated by SEM and Raman spectroscopy, respectively. The results showed that the conversion of V
2
O
5
powder to VO
2
thin films was dominated by a melting-evaporation-nucleation-growth mechanism. Further characterization results demonstrated that the high quality crystals of monoclinic VO
2
thin films exhibit a sharp resistance change up to 4 orders of magnitude. In addition, the VO
2
thin films exhibited good near-infrared response, high stability, and reproducibility under ambient conditions, which should be promising for sensitive near-infrared detection. Our work not only provided a simple and direct approach to synthesize high quality VO
2
thin films with distinct phase transition properties but also demonstrated the possible infrared sensing application in the future.
As the progress of electronics and information processing technology continues, indoor localization has become a research hotspot in wireless sensor networks (WSN). The adverse non-line of sight ...(NLOS) propagation usually causes large measurement errors in complex indoor environments. It could decrease the localization accuracy seriously. A traditional grey model considers the motion characteristics but does not take the NLOS propagation into account. A robust interacting multiple model (R-IMM) could effectively mitigate NLOS errors but the clipping point is hard to choose. In order to easily cope with NLOS errors, we present a novel filter framework: mixture Gaussian fitting-based grey Kalman filter structure (MGF-GKFS). Firstly, grey Kalman filter (GKF) is proposed to pre-process the measured distance, which can mitigate the process noise and alleviate NLOS errors. Secondly, we calculate the residual which is the difference between the filtered distance of GKF and the measured distance. Thirdly, a soft decision method based on mixture Gaussian fitting (MGF) is proposed to identify the propagation condition through residual value and give the degree of membership. Fourthly, weak NLOS noise is further processed by unscented Kalman filter (UKF). The filtered results of GKF and UKF are weighted using the degree of membership. Finally, a maximum likelihood (ML) algorithm is applied to get the coordinate of the target. MGF-GKFS is not supported by any of the priori knowledge. Full-scale simulations and an experiment are conducted to compare the localization accuracy and robustness with the state-of-the-art algorithms, including robust interacting multiple model (R-IMM), unscented Kalman filter (UKF) and interacting multiple model (IMM). The results show that MGF-GKFS could achieve significant improvement compared to R-IMM, UKF and IMM algorithms.
Halide perovskite materials have broad prospects for applications in various fields such as solar cells, LED devices, photodetectors, fluorescence labeling, bioimaging, and photocatalysis due to ...their bandgap characteristics. This study compiled experimental data from the published literature and utilized the excellent predictive capabilities, low overfitting risk, and strong robustness of ensemble learning models to analyze the bandgaps of halide perovskite compounds. The results demonstrate the effectiveness of ensemble learning decision tree models, especially the gradient boosting decision tree model, with a root mean square error of 0.090 eV, a mean absolute error of 0.053 eV, and a determination coefficient of 93.11%. Research on data related to ratios calculated through element molar quantity normalization indicates significant influences of ions at the X and B positions on the bandgap. Additionally, doping with iodine atoms can effectively reduce the intrinsic bandgap, while hybridization of the s and p orbitals of tin atoms can also decrease the bandgap. The accuracy of the model is validated by predicting the bandgap of the photovoltaic material MASn1−xPbxI3. In conclusion, this study emphasizes the positive impact of machine learning on material development, especially in predicting the bandgaps of halide perovskite compounds, where ensemble learning methods demonstrate significant advantages.
The photocatalysis is a very promising technique to address the serious issues of environmental pollution. Among the common photocatalysts, the graphitic carbon nitride (g-C
3
N
4
) is widely used ...for the photodegradation of organic pollutants due to its proper band structure. To further improve the photocatalytic performance of g-C
3
N
4
, a novel composite photocatalyst of Co
3
O
4
/PT-C
3
N
4
has been prepared by using a one-pot calcination method, in which cobalt tetroxide (Co
3
O
4
) nanoparticles as the cocatalyst are introduced on the surface of rectangular hollow g-C
3
N
4
substrate (PT-Co
3
O
4
). As a result, the obtained composite photocatalyst (Co3O
4
/PT-C
3
N
4
) delivers an excellent photodegradation performance for diesel oil under a simulated sunlight, which can improve the separation efficiency of the photo-induced electron–hole pairs. The Co
3
O
4
/PT-C
3
N
4
composite photocatalyst exhibits a high degradation efficiency of 96.27% after 2 h of visible light, which is much higher than that of the PT-C
3
N
4
photocatalyst. Moreover, the composite photocatalyst can still maintain a high photodegradation efficiency after 10 cycles, exhibiting an excellent cyclic stability. The photo-induced carriers generated by the Co
3
O
4
/PT-C
3
N
4
composite photocatalyst follow the Z-scheme heterojunction transfer mechanism. This work gives a fresh idea for the exploration of new high-performance photocatalyst for the treatment of organic environmental pollutants.
Graphical Abstract
We explore the electronic structure of two-dimensional (2D) MnPSe
3
/MoS
2
van der Waals (vdW) heterostructures based on density functional theory. A novel spin splitting at the valance band maximum ...of MnPSe
3
appears in some specific stacking models due to Mn
d
orbital hybridization. The simultaneous spin and valley splitting can be achieved by interfacial coupling, which is attractive for manipulation of the valley and spin degrees of freedom. More importantly, due to the antiferromagnetic ordering of manganese, the opposite spin moments at
K
and
K′
valleys can be observed by transforming configurations, which realizes the tunable spin splitting states. Our theoretical work opens up the opportunities of valley and spin related applications of MnPSe
3
/MoS
2
vdW heterostructures and offers a practical avenue for exploring novel devices based on the spin and valley degrees of freedom.
Ni/SBA-15 modified by highly dispersed cerium-oxide was prepared with the aid of sucrose for steam reforming of JP10 (C10H16). Their characterization showed that addition of appropriate amount ceria ...led to the formation of highly dispersed CeO2 and Ni, and the CeO2 covered smaller nickel particles like strawberry seeds to form much more interface between them. Their catalytic activity exhibited higher stability over time on stream of 6.5 h with conversion higher than 95% and higher carbon resistance (mass loss less than 4.5% by TG), which may derive from good properties below: (1) much more interface enhanced cooperation effect and increased turnover frequency at the interface; (2) the stronger interaction between Ni and ceria to suppress sintering by formation of Ni-O-Ce solid solution; (3) the large amount of oxygen vacancies from the formation of Ni-O-Ce solid solution and highly dispersed CeO2 to facilitate the water–gas–shift reaction and carbon removal.
The photocatalysis of graphtic carbon nitride (g-C
3
N
4
) material has been widely used for the photocatalytic degradation of organic pollutants. However, g-C
3
N
4
still has some drawbacks, such as ...the high recombination of photo-induced electron–hole pairs and weak absorption of light irradiation. To further improve the photodegradation performance of g-C
3
N
4
, a novel composite photocatalyst (CoO/ PT-C
3
N
4
) has been prepared by using a one-pot calcination method, in which cobalt oxide (CoO) as a cocatalyst are introduced on the rectangular hollow substrate of g-C
3
N
4
(PT-C
3
N
4
), The CoO/PT-C
3
N
4
composite photocatalyst delivers an excellent photodegradation performance for diesel oil under a simulated sunlight. It exhibits a high degradation efficiency of 95.92% after light irradiation for 2 h, which is much higher than that of pristine PT-C
3
N
4
. Free radical capture experiments manifest that the free radical of ·O
2−
plays a major role for the photodegradation and main active radicals abide by the sequence: ·O
2−
> ·OH > h
+
. Moreover, the CoO/PT-C
3
N
4
composite photocatalyst delivers an excellent cyclic stability, which only degrades 8.71% photodegradation efficiency after 10 cycles. The improvement of CoO/PT-C
3
N
4
composite photocatalyst is ascribed to the formation of a heterojunction between CoO and PT-C
3
N
4
, which promotes the separation of photo-induced carriers. This work paves a new way for the exploration of photocatalyst for the organic pollutant degradation.
Charge transfer, surface/interface, defect states, and internal fields strongly influence carrier statics and dynamics in semiconductor nanowires. These effects are usually probed using spatially ...resolved scanning current techniques, where charge carriers are driven to move by diffusion force due to a density gradient, drift force due to internal fields, and thermoelectric force due to a temperature gradient. However, in the analysis of experimental data, analytical formulas are usually used which are based on the assumption that a single component of these forces dominates the carrier dynamics. In this work we show that this simplification is generally not justified even in the simplest configurations, and the scanning microscopy data need to be analyzed with caution. We performed a comprehensive numerical modeling of the electrothermal dynamics of free charge carriers in the scanning photocurrent microscopy configuration. The simulation allows us to reveal and predict important, surprising effects that are previously not recognized, and assess the limitation as well as potential of these scanning current techniques in nanowire characterization.
PDF
