Ultrasound Induces Local Disorder of FeOOH on CdIn2S4 Photoanode for High Efficiency Photoelectrochemical Water Oxidation.

The regulation of the crystal structure of oxygen evolution cocatalyst (OEC) is a promising strategy for enhancing the photoelectrochemical efficiency of photoanodes. However, the prevailing regulating approach typically requires a multistep procedure, presenting a significant challenge for maintaining the structural integrity and performance of the photoanode. Herein, FeOOH with a local disordered structure is directly grown on a CdIn2S4 (CIS) photoanode via a simple and mild sonochemical approach. By modulating the localized supersaturation of Ni ions, ultrasonic cavitation induces Ni ions to participate in the nucleation and growth of FeOOH clusters to cause local disorder of FeOOH. Consequently, the local disordered FeOOH facilitates the exposure of additional active sites, boosting OER kinetics and extending charge carrier lifetimes. Finally, the optimal photoanode reaches 4.52 mA cm-2 at 1.23 VRHE, and the onset potential shifts negatively by 330 mV, exhibiting excellent performance compared with that of other metal sulfide-based photoelectrodes reported thus far. This work provides a mild and controllable sonochemical method for regulating the phase structure of OECs to construct high-performance photoanodes.

Improved Dual-Polarity Response via Pyro-phototronic Effect for Filterless Visible Light Communication.

Dual-polarity response photodetectors (PDs) take full advantage of the directivity of the photocurrent to identify optical information. The dual-polarity signal ratio, a key parameter that represents the equilibrium degree of responses to different lights, is proposed for the first time. The synchronous enhancement of dual-polarity photocurrents and the amelioration of the dual-polarity signal ratio are beneficial to the practical applications. Herein, based on the selective light absorption and energy band structure design, a self-powered CdS/PEDOT:PSS/Au heterojunction PD consisting of a p-n junction and a Schottky junction exhibits unique wavelength-dependent dual-polarity response, where the photocurrent is negative and positive in the short and long wavelength regions, respectively. More importantly, the pyro-phototronic effect inside the CdS layer significantly improves the dual-polarity photocurrents with the maximum enhancement factors of 120%, 343%, 1167%, 1577%, and 1896% at 405, 450, 532, 650, and 808 nm, respectively. Furthermore, the dual-polarity signal ratio tends to 1:1 due to different degrees of the enhancement. This work provides a novel design strategy for dual-polarity response PDs with a simple working principle and improved performance, which can supply a substitution for two traditional PDs in the filterless visible light communication (VLC) system.

Switchable terahertz orbital angular momentum Bessel beams based on spin-decoupled multifunctional reflective metasurfaces.

In this study, switchable terahertz (THz) multi-orbital angular momentum (OAM) Bessel beams (BBs) were developed based on a spin-decoupled reflective multifunctional metasurface (MTS). Switchability was achieved by switching the feed between left-hand circular polarization (LCP), right-hand circular polarization (RCP), and linear polarization (LP) incidences. A switchable physical model was established for calculating the beam direction, OAM mode, polarization, and non-diffractive distance of the outgoing BBs. As an example, a spin-decoupled MTS was designed to generate dual BBs under LCP incidence, which was subsequently switched to RCP or LP for switchability. The outgoing BBs could be switched among three types of beams: Type-1 under LCP incidence (LCP, θL = 40°, φL = 0°, lL = 1, dL = 18 cm) and (RCP, θR = -40°, φR = 0°, lR = -1, dR = 20 cm); Type-2 under RCP incidence (RCP, θR = 40°, φR = 0°, lR = 1, dR = 18 cm) and (LCP, θL = -19°, φL = 0°, lL = 3, dL = 16.4 cm); and Type-3 under LP incidence (LP, θ = 40°, φ = 0°, l = 1, d = 18 cm), (RCP, θR = -40°, φR = 0°, lR = -1, dR = 20 cm) and (LCP, θL = -19°, φL = 0°, lL = 3, dL = 16.4 cm). Compared with previous MTSs, the proposed spin-decoupled MTS has the advantages of switchability among BBs, high non-diffractive distance/aperture size ratio of 15, large beam deflection angle of up to 40°, and high BB conversion efficiency of up to 96%. The simulated results were consistent with those calculated using the physical model, thus validating the physical model. The designed switchable BBs have potential THz near-field applications, such as high-capacity near-field wireless communications, wireless power transfer, high-resolution imaging, non-destructive testing, and speed detection of high-speed rotating objects.

Constructing a High-Quality t-Se/Si Interface Via In Situ Light Annealing of a-Se for a Self-Powered Image Sensor.

The quality of the interface, e.g., the semiconductor-semiconductor or metal-semiconductor interface, is the main factor restricting the photodetection performance of a heterojunction. In this study, a high-quality Se/Si interface is constructed via in situ directional transformation of amorphous Se (a-Se) into crystalline Se (t-Se) on a Si substrate via light annealing. Benefitting from the high-quality interface and appropriate energy band between Si and Se, the t-Se/Si heterojunction exhibits an extremely high responsivity and detectivity of 583.33 mA W-1 and 8.52 × 1012 Jones at 760 nm, respectively. In addition, the device exhibits an ultrafast rise time of 183 µs and a decay time of 405 µs. Furthermore, an image sensor fabricated via local light annealing successfully recognizes patterns of "N," "P," and "U." This study provides valuable guidance for the construction of high-quality interfaces and the design of self-powered image sensors.

Circular Photogalvanic Effect in Oxide Two-Dimensional Electron Gases.

Two-dimensional electron gases (2DEGs) at the LaAlO_{3}/SrTiO_{3} interface have attracted wide interest, and some exotic phenomena are observed, including 2D superconductivity, 2D magnetism, and diverse effects associated with Rashba spin-orbit coupling. Despite the intensive investigations, however, there are still hidden aspects that remain unexplored. For the first time, here we report on the circular photogalvanic effect (CPGE) for the oxide 2DEG. Spin polarized electrons are selectively excited by circular polarized light from the in-gap states of SrTiO_{3} to 2DEG and are converted into electric current via the mechanism of spin-momentum locking arising from Rashba spin-orbit coupling. Moreover, the CPGE can be effectively modified by the density and distribution of oxygen vacancies. This Letter presents an effective approach to generate and manipulate the spin polarized current, paving the way toward oxide spintronics.

Occurrence and formation pathways analysis of PBDD/Fs from 2,4,6-tribromophenol under thermal reaction conditions.

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) are highly toxic and persistent compounds that provoke a wave of publicity. Bromophenols are important precursors for forming PBDD/Fs, and their reaction path has always been a research hotspot. In this study, the formation characteristic of PBDD/Fs from 2,4,6-TBP were studied. The yields of 2,3,7,8-substituted PBDD/Fs and 2,4,6,8-TBDF for the different thermal products ranged from 0.067 to 10.3 ng/g and 0.207-9.68 ng/g, respectively. The effects of adding Cu, Fe, and Sb2O3 were investigated and found to be more inclined to accelerate the formation of ortho-substituted PBDD/Fs than 2,3,7,8-PBDD/Fs. The formation pathways of 2,3,7,8-substituted PBDD/Fs and 2,4,6,8-TBDF were also proposed. 2,4,6,8-TBDF is generated in the C-C coupling reactions of some radical intermediates from the debromination of 2,4,6-TBP. The 2,3,7,8-PBDD/Fs are produced through more complex debromination, bromine substitution, and bromine rearrangement reactions. In addition, various catalytic effects on PBDD/F formation pathways were found, and the catalytic effect of Cu by the Ullmann reaction was the highest, while bromophenol oxidation by Fe was the highest. These results proved that both 2,3,7,8-substituted and non-2,3,7,8-substituted PBDD/Fs would be generated from 2,4,6-TBP, and the effects of the catalyst on the Br substituted position of 2,3,7,8-substituted PBDD/Fs were much lower than the Br-substituted position on bromophenol.

Pathways and influential factors study on the formation of PBDD/Fs during co-processing BDE-209 in cement kiln simulation system.

The thermal processes of cement kilns are sources of polybrominated dibenzofurans and dioxins (PBDD/Fs); however, when co-processing decabromodiphenyl ether (BDE-209) soil in cement kilns, very few reports have investigated the mechanism of PBDD/Fs formation from BDE-209. Therefore, the pathways and factors that influence the formation of PBDD/Fs were investigated using Box-Behnken design (BBD) of the response surface methodology (RSM) at lab-scale. The PBDEs, HBr/Br2 and PBDD/Fs emissions in flue gas from the simulated thermal process were analyzed using gas chromatography/mass spectroscopy (GC/MS), high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS), and ion chromatography (IC). Density functional theory (DFT) was also used to further discuss the formation of PBDD/Fs. The major products of BDE-209 thermal decomposition in flue gas were 97.1% HBr/Br2 (a.v. 26.6%/70.6%) > 2.7% PBDEs >0.2% PBDD/Fs. Formation of precursors were the main pathways for PBDD/Fs, and those precursors were dominated by higher-brominated PBDEs (heptã deca-BDEs); debromination of BDE-209 was also a crucial pathway for the formation of PBDD/Fs throughout the thermal process. Interestingly, it was easier to form HpBDD/Fs from OBDD/Fs than from PBDEs. The O2 percentage and interaction factors of O2 percentage, temperature, and CaCO3 percentage have the largest influence on PBDD/Fs emissions and formation.

Approach of realizing arbitrary wavefront manipulation with continuous meander line structures.

In the paper, we systematically present the approach of realizing arbitrary wavefront manipulation with continuous meander line structures that can send the outgoing light with the opposite polarization in respect to the incident light into desired directions. The manipulation behavior is found to be wavelength-dependent, analogous to the traditional grating. Propagation characteristic and filed analysis are used to understand the generation of the polarization conversed outgoing light. The results suggest that the surface mode of TM component mainly governs at long wavelength and the oscillating mode of TE component is dominant at short wavelength, resulting in a broad operation region. The backward process, i.e., deriving a special function based on the given irradiation pattern, verifies the generation of the approach. The finding gives an alternative to realize the wavefront manipulation of transmitted light with a thin metal device and an insight into the traditional meander line structure.

Low dark current broadband 360-1650 nm ITO/Ag/n-Si Schottky photodetectors.

This work designed an ITO/Ag/n-Si Schottky photodetector with broad wavelength detection and low dark current. The introduction of Ag interfacial layer and post rapid thermal annealing dramatically increase the barrier height of ITO/n-Si Schottky diode by 0.32 eV, leading to the 2300 × reduction of dark current. A well-behaved ITO/Ag (8 nm)/n-Si Schottky diode with a high rectification ratio ( ± 1 V) of 4 × 105 and low dark current (-1 V) of 9.2 nA was achieved. Such low dark current device spontaneously provides high sensitivity for visible/near infrared wavelength detection, in which substantial responsivity for wavelengths from 360 to 1650 nm was realized through both inter-band and internal photoemission. The design here provides an encouraging strategy for monolithically integrated pure Si photodetectors operating at long wavelength up to 1650 nm.

Spatial distribution of and seasonal variations in endosulfan concentrations in soil, air, and biota around a contaminated site.

Soil, air, tree bark, rice, wheat, invertebrates, and chicken tissues around a typical endosulfan-contaminated site were analyzed in each season in each of two years. The total endosulfan (the sum of α-, ß-endosulfan and endosulfan sulfate) were significantly different in soil and air samples collected in the four seasons (P < 0.01) and the mean concentrations were 6.53 ng/g dry weight (d.w.) and 2.40 ng/m3, respectively, in autumn, 3.32 ng/g d.w. and 2.48 ng/m3, respectively, in winter, 2.10 ng/g d.w. and 0.93 ng/m3, respectively, in spring, and 1.03 ng/g d.w. and 0.83 ng/m3, respectively, in summer. The total endosulfan concentrations in tree bark, rice, wheat, and invertebrates were 23.0-278 (mean 95.5) ng/g d.w., 7.36-35.5 (mean 17.4) ng/g d.w., 34.3-158 (mean 83.1) ng/g d.w., and 401-4354 (mean 2125) ng/g lipid weight, respectively. The total endosulfan concentrations in the chicken gizzard, heart, liver, and meat samples were 552, 212, 699, and 221 ng/g lipid weight, respectively. The endosulfan concentrations in soil, air, and biota around the site were strongly influenced by endosulfan emissions from the site, and the concentrations had decreased to half the initial concentrations six months after endosulfan production stopped. The invertebrate and chicken bioconcentration and biomagnification factors indicated that endosulfan accumulated in the invertebrates and chicken tissues was slightly biomagnified by chickens.

Monodisperse, Self-Activated Luminescent, and Mesoporous Silica Nanospheres for Drug Delivery.

Monodisperse mesoporous silica nanospheres with novel self-activated luminescence have been fabricated by a modified templating sol­gel method followed by heat treatment, without introducing any rare earth or transition metal ions as activators. The SEM, TEM, and N2 adsorption/desorption isotherms results show that the as-obtained mesoporous silica nanospheres exhibit well-defined morphology, good dispersion, high specific surface area and pore volume. MTT assay indicates that the sample exhibits no obvious cytotoxicity against the A549, HeLa, and MCF-7 cells, which make it suitable to be utilized as a drug carrier. Under ultraviolet excitation, the sample exhibits an intense blue emission. Interestingly, the photoluminescence intensity of the IBU drug loaded system increases with the increase of cumulatively released IBU. Due to the relationship between the luminescence properties and drug release behavior, the as-obtained luminescent drug carrier may be potential as a probe for monitoring or detecting the drug release process.

Filter-Less Color-Selective Photodetector Derived from Integration of Parallel Perovskite Photoelectric Response Units.

Color-selective photodetectors (PDs) play an indispensable role in spectral recognition, image sensing, and other fields. Nevertheless, complex filters and delicate optical paths in such devices significantly increase their complexity and size, which subsequently impede their integration in smart optoelectronic chips for universal applications. This work demonstrates the successful fabrication of filter-less color-selective perovskite PDs by integrating three perovskite units with different photoresponse on a single chip. The variation in photoresponse is attributed to different quantities of SnO2 nanoparticles, synthesized through controlled ultrasonic treatment on the surface of the electron transportation layer SnS2, which selectively absorb short-wavelength light, thus increasing the relative transmittance of long-wavelength light and enhancing the photoresponse of the units to long wavelengths. By integrating any two units and deriving the formula for the wavelength to the responsivity ratio, a wavelength sensor is developed which can accurately identify incident light in the range of 400-700 nm with a minimum error <3 nm. Furthermore, the device integrating three units with different photoresponse can identify red, green and blue in polychromatic light to achieve color imaging with a relative error <6%. This work provides valuable insights into wavelength identification and color imaging of perovskite PDs.

Sonochemical regulation of oxygen vacancies for Bi2WO6 nanosheet-based photoanodes to promote photoelectrochemical performance.

Integration of oxygen vacancies (Vo) into nanostructured semiconductor-based photocatalysts has been recognized as a promising strategy for enhancing the performance of photoelectrochemical (PEC) water splitting. However, precisely controlling the Vo concentration in photocatalysts via an effective and tunable approach remains challenging. Herein, a series of optimized bismuth tungstate (Bi2WO6) nanosheet-based photoanodes with varying concentrations of Vo were prepared by a sonochemical method with in situ cavitation detection, which enables accurate manipulation of the acoustic cavitation intensity applied to the surface of Bi2WO6 photoanodes in alkaline solution. Based on the analysis of the Vo concentration and sound field characteristics, the mechanism of sonochemical regulation of Vo in Bi2WO6 nanosheets was interpreted. Specifically, the increase in Vo concentration can be attributed to the enhancement of Bi-O bond dissociation. This enhancement is influenced not only by the intensified impact of shear force and the generation of active radicals by transient cavitation, but also by the accelerated diffusion of the reactant, a result of stable cavitation. By optimizing the transient and stable cavitation intensity, a Vo-rich Bi2WO6 photoanode was obtained without altering the microstructure of Bi2WO6 nanosheets. The presence of high concentration Vo facilitates the interfacial chemical reactivity and the transmission of photogenerated carriers, leading to the drastic promotion of the PEC water splitting performance. The transient photocurrent density of the Vo-rich Bi2WO6 photoanode reaches 69.2 µA cm-2 (1.23 V vs. RHE), 7.86 times that of the untreated Bi2WO6 photoanode. Additionally, the charge injection efficiency increases to 35.4%. This work provides a controllable and effective method for defect engineering of nanostructured semiconductor-based electrodes.

A Multistate Non-Volatile Photoelectronic Memory Device Based on Ferroelectric Tunnel Junction with Modulable Visible Light Photoresponse.

Recently, certain ferroelectric tunnel junctions (FTJs) exhibit non-volatile modulations on photoresponse as well as tunneling electroresistance (TER) effects related to ferroelectric polarization states. From the opposite perspective, the corresponding polarization states can be read by detecting the levels of the photocurrent. In this study, we fabricate a novel amorphous selenium (a-Se)/PbZr0.2Ti0.8O3 (PZT)/Nb-doped SrTiO3 (NSTO) heterojunction, which exhibits a high TER of 3 × 106. Unlike perovskite oxide FTJs with a limited ultraviolet response, the introduction of a narrow bandgap semiconductor (a-Se) enables self-powered photoresponse within the visible light range. The self-powered photoresponse characteristics can be significantly modulated by ferroelectric polarization. The photocurrent after writing polarization voltages of +4 and -5 V exhibits a 1200% increase. Furthermore, the photocurrent could be clearly distinguished after writing stepwise polarization voltages, and then a multistate information storage is designed with nondestructive readout capacity under light illumination. This work holds great significance in advancing the development of ferroelectric multistate photoelectronic memories with high storage density and expanding the design possibilities for FTJs.

Spatial Steerability of GANs via Self-Supervision from Discriminator.

Generative models make huge progress to the photorealistic image synthesis in recent years. To enable human to steer the image generation process and customize the output, many works explore the interpretable dimensions of the latent space in GANs. Existing methods edit the attributes of the output image such as orientation or color scheme by varying the latent code along certain directions. However, these methods usually require additional human annotations for each pretrained model, and they mostly focus on editing global attributes. In this work, we propose a self-supervised approach to improve the spatial steerability of GANs without searching for steerable directions in the latent space or requiring extra annotations. Specifically, we design randomly sampled Gaussian heatmaps to be encoded into the intermediate layers of generative models as spatial inductive bias. Along with training the GAN model from scratch, these heatmaps are being aligned with the emerging attention of the GAN's discriminator in a self-supervised learning manner. During inference, users can interact with the spatial heatmaps in an intuitive manner, enabling them to edit the output image by adjusting the scene layout, moving, or removing objects. Moreover, we incorporate DragGAN into our framework, which facilitates fine-grained manipulation within a reasonable time and supports a coarse-to-fine editing process. Extensive experiments show that the proposed method not only enables spatial editing over human faces, animal faces, outdoor scenes, and complicated multi-object indoor scenes but also brings improvement in synthesis quality. Code, models, and demo video are available at https://genforce.github.io/SpatialGAN/.

High-performance flexible p-type Ce-filled Fe3CoSb12 skutterudite thin film for medium-to-high-temperature applications.

P-type Fe3CoSb12-based skutterudite thin films are successfully fabricated, exhibiting high thermoelectric performance, stability, and flexibility at medium-to-high temperatures, based on preparing custom target materials and employing advanced pulsed laser deposition techniques to address the bonding challenge between the thin films and high-temperature flexible polyimide substrates. Through the optimization of fabrication processing and nominal doping concentration of Ce, the thin films show a power factor of >100 µW m-1 K-2 and a ZT close to 0.6 at 653 K. After >2000 bending cycle tests at a radius of 4 mm, only a 6 % change in resistivity can be observed. Additionally, the assembled p-type Fe3CoSb12-based flexible device exhibits a power density of 135.7 µW cm-2 under a temperature difference of 100 K with the hot side at 623 K. This work fills a gap in the realization of flexible thermoelectric devices in the medium-to-high-temperature range and holds significant practical application value.

Self-Powered Wavelength-Dependent Dual-Polarity Response Photodetector Based on CdS@PEDOT:PSS@Au Sandwich-Structured Core-Shell Nanorod Arrays.

Self-powered operation and multifunctionality have significantly oriented the development of photodetectors (PDs), which could be realized through nanoarchitecture construction and energy band structure design. Herein, a self-powered wavelength-dependent dual-polarity response PD based on (CdS@PEDOT:PSS@Au) sandwich-structured core-shell nanorod arrays (NRAs) is proposed. The synthesis approach of this three-layer heterostructure consists of a hydrothermal reaction, spin coating, and thermal evaporation. The n-CdS/p-PEDOT:PSS junction and the PEDOT:PSS/Au Schottky junction at the interfaces provide two photocurrent driving forces in opposite directions, and their contribution to the net photocurrent is controlled by the incident light wavelength due to the different light absorption ranges of the CdS core and the PEDOT:PSS shell. As a result, the polarity of the photocurrent switches from negative to positive as the wavelength increases. In addition, the response speed of negative photocurrents (∼10 ms) is faster than that of positive photocurrents (∼100 ms), which is consistent with the underlying mechanism of the dual-polarity response. Furthermore, color discrimination and imaging capabilities are demonstrated by deploying the PDs as sensing pixels and recognizing green and red patterns. The sandwich-structured core-shell NRA heterojunction system introduces a novel idea for dual-polarity response PDs.

IFKD: Implicit field knowledge distillation for single view reconstruction.

In 3D reconstruction tasks, camera parameter matrix estimation is usually used to present the single view of an object, which is not necessary when mapping the 3D point to 2D image. The single view reconstruction task should care more about the quality of reconstruction instead of the alignment. So in this paper, we propose an implicit field knowledge distillation model (IFKD) to reconstruct 3D objects from the single view. Transformations are performed on 3D points instead of the camera and keep the camera coordinate identified with the world coordinate, so that the extrinsic matrix can be omitted. Besides, a knowledge distillation structure from 3D voxel to the feature vector is established to further refine the feature description of 3D objects. Thus, the details of a 3D model can be better captured by the proposed model. This paper adopts ShapeNet Core dataset to verify the effectiveness of the IFKD model. Experiments show that IFKD has strong advantages in IOU and other core indicators compared with the camera matrix estimation methods, which verifies the feasibility of the new proposed mapping method.

Video-based Person re-identification with parallel correction and fusion of pedestrian area features.

Deep learning has provided powerful support for person re-identification (person re-id) over the years, and superior performance has been achieved by state-of-the-art. While under practical application scenarios such as public monitoring, the cameras' resolutions are usually 720p, the captured pedestrian areas tend to be closer to 128×64 small pixel size. Research on person re-id at 128×64 small pixel size is limited by less effective pixel information. The frame image qualities are degraded and inter-frame information complementation requires a more careful selection of beneficial frames. Meanwhile, there are various large differences in person images, such as misalignment and image noise, which are harder to distinguish from person information at the small size, and eliminating a specific sub-variance is still not robust enough. The Person Feature Correction and Fusion Network (FCFNet) proposed in this paper introduces three sub-modules, which strive to extract discriminate video-level features from the perspectives of "using complementary valid information between frames" and "correcting large variances of person features". The inter-frame attention mechanism is introduced through frame quality assessment, guiding informative features to dominate the fusion process and generating a preliminary frame quality score to filter low-quality frames. Two other feature correction modules are fitted to optimize the model's ability to perceive information from small-sized images. The experiments on four benchmark datasets confirm the effectiveness of FCFNet.

A high-temperature acoustic field measurement and analysis system for determining cavitation intensity in ultrasonically solidified metallic alloys.

A high-temperature acoustic field measurement and analysis system (HTAFS) was self-designed and developed to achieve real-time acoustic field analysis and quantitative cavitation characterization within high-temperature liquids. The acoustic signal was acquired by a high-temperature resistant waveguide and calibrated by separate compensation of line and continuous spectra to eliminate frequency offsets. Moreover, a new method was proposed to derive from the continuous-spectrum sound intensity and line-spectrum sound intensity in the frequency band above 1.5 times the fundamental frequency to characterize the intensity of transient cavitation and stable cavitation. The acoustic field characteristics within solidifying liquid Al-7 %Si alloy were successfully determined by this system. With the increase of ultrasound amplitude, the acoustic pressure in the alloy melt increased to be stable, the transient cavitation intensity first rose and then declined, and the stable cavitation intensity remained unchanged. Combined with the structural evolution of the primary α(Al) phase, the transient cavitation intensity was determined to be the dominant factor for the ultrasound-induced grain refinement effect.