Water resources are an indispensable part of life, but the current water pollution problem is facing serious challenges. In this article, two-dimensional g-C3N4 and h-BN used as raw materials, a series of h-BN/g-C3N4 (BCN) composite catalysts with varying mass by designed and synthesized using combination of simple solvent volatilization and high-temperature thermal polymerization method. The degradation rate of the BCN-2 catalyst was impressively 13.7 times higher than that of the bulk g-C3N4 when RhB was used as the target pollutants, demonstrating significantly enhanced photocatalytic performance compared to both bulk g-C3N4 and h-BN. The burst experiments on free radicals revealed that h+ and ∙O2− played a predominant role in the photocatalytic system. Moreover, the introduction of h-BN into g-C3N4 nanosheets modulated their microstructure, facilitating effectively hole migration channels and enhancing synergistically the separation efficiency of photogenerated electron-hole pairs. Consequently, the composites of h-BN/g-C3N4 with remarkably enhanced photocatalytic activity were obtained.

Triboelectric sensors, which are used in human-computer interaction and condition monitoring, have attracted tremendous scientific interest owing to their broad applicability, high energy utilization, and high accuracy detection. Here, a staircase-style flexible triboelectric sensor assembled by the antimony-doped tin oxide (ATO) functionalized flexible polyvinylidene fluoride polymer (PVDF) composite film is first proposed for gesture recognition and human motion detection. The modified composite film ATO/PVDF with high polarization and large permittivity improves the electrical output of the triboelectric nanogenerator (TENG). Compared with the pure PVDF, the modified PVDF film-based TENG could substantially enhance power density by 11.5 times. The peak voltage and power density of the flexible staircase-style TENG achieve 70V and 0.58W/m2, respectively. The flexible triboelectric sensor can be attached to the finger or wrist to obtain movement information through positive/negative signals. A set of rules between gestures and corresponding letters and numbers is defined and a gesture recognition system using deep learning algorithms is developed. The flexible triboelectric sensor realizes human body part bending, gesture, and motion state recognition, offering potential solutions and novel possibilities in smart sensing and human-computer interaction.

In this article, high-voltage (HV) electrostatic discharge (ESD) protection devices with high robustness and strong radiation tolerance are investigated by technology computer-aided design (TCAD) simulations and transmission line pulse (TLP) measurements. The TLP measurement results of laterally diffused MOS (LDMOS)-silicon-controlled rectifier (SCR) fabricated in 0.35 mu m bipolar-CMOS-DMOS (BCD) process demonstrated that its ESD robustness is elevated by 58% than that of LDMOS and is up to 13 kV human body model protection level. Meanwhile, high holding voltage and current of 17 V and 1.8 A are achieved by low-voltage MOS (LV-MOS) cascade technology in LDMOS-SCR. TLP I-V curves and transient voltage waveforms exhibit high operational stability of LDMOS-SCR. Gamma-ray irradiation experiments show strong radiation tolerance of LDMOS-SCR, whose ESD performance had almost no degradation under total ionizing dose (TID) radiation of 200 krad(Si), while the failure current of LDMOS decreased by 2 A. Therefore, a properly designed LDMOS-SCR is an excellent ESD protection device for HV circuits, especially in space applications.

Helical edge states (HESs) in two-dimensional topological spin photonic crystals can be used to realize pseudospin-locked unidirectional propagation of waves. In general, the excitation of HESs is by taking light sources carrying orbital angular momentum of order 1 to stimulate the pseudospin p states in spin photonic crystals. In this paper, we think of the HESs as combinations of the pseudospin p states and the pseudospin d states, which corresponding to the pseudospin modes carrying orbital angular momentum of order 1 and the pseudospin modes carrying orbital angular momentum of order 2, respectively, with their chirality related to the unidirectional propagations of the HESs. By analyzing the field distributions of HESs and via exciting the pseudospin d states with light sources carrying orbital angular momentum of order 2, we demonstrate the unidirectional propagation of the HESs in spin photonic crystals and verify their robustness by checking the unidirectional performance as they propagate along a Z-shape interface containing sharp corners, cavity defect, and disorders. Our study deepens understanding of the nature of HESs and expands methods to excitation and regulation of HESs in topological spin photonics.

Topologically protected magnetic "whirls" such as skyrmions in antiferromagnetic materials have recently attracted extensive interest due to their nontrivial band topology and potential application in antiferromagnetic spintronics. However, room-temperature skyrmions in natural metallic antiferromagnetic materials with merit of probable convenient electrical manipulation have not been reported. Here, room-temperature skyrmions are realized in a non-collinear antiferromagnet, Mn3 Sn, capped with a Pt overlayer. The evolution of spin textures from coplanar inverted triangular structures to Bloch-type skyrmions is achieved via tuning the magnitude of interfacial Dzyaloshinskii-Moriya interaction. Beyond that, the temperature can induce an unconventional transition from skyrmions to antiferromagnetic meron-like spin textures at ≈220 K in the Mn3 Sn/Pt samples. Combining with the theoretical calculations, it is found that the transition originates from the temperature dependence of antiferromagnetic exchange interaction between kagome sublayers within the Mn3 Sn crystalline unit-cell. These findings open the avenue for the development of topological spin-swirling-based antiferromagnetic spintronics.

We present a theoretically investigation about the electron transport through a single-barrier structures in HgTe/CdTe quantum wells (QWs) with inverted band structure. For HgTe/CdTe QWs structure, the transmission probabilities show great dependence on the Rashba spin–orbit interaction (RSOI), the incident angle, the incident Fermi energy and the electric modulation potential. By tuning the modulation amplitude with gate voltage or the strength of RSOI modulation, the efficient spin-polarized PZ=1 is achieved, which is formed due to the spin-split in band spectrum induced by the RSOI modulation. This electric mechanism provides us a way to manipulate the spin polarization electrically and convenient for experimental verification.

Magnetic tunnel junctions (MTJs) with ferromagnetic (FM) and/or antiferromagnetic (AFM) materials have attracted wide interest for their promising application in spintronic devices. Recently, many discovered two-dimensional (2D) magnetic materials offer a flexible platform to design switchable layered FM/AFM MTJs. By using the first-principles quantum transport simulations, we designed the MTJs based on 2D van der Waals layered MnBi _2 Te _4 and studied the spin-dependent electronic and transport properties of the MTJs with the different thickness MnBi _2 Te _4 as well as their FM and AFM configurations. As the increment of MnBi _2 Te _4 layers, our results show that there is a higher spin polarization and the tunnel magnetoresistance (TMR) ratio at the Fermi level correspondingly increases: 100 _2 Te _4 -based MTJs. For Moore’s Law to continue to work, there is an urgent demand to find new principles, new materials, and more concepts for future devices. Among them, spintronics has exhibited great potential due to its excellent performance. A typical widely used device is the magnetic tunnel junction (MTJ) in spintronics. Recently, more and more MTJs based on discovered two-dimensional magnetic materials have been predicted with higher tunnel magnetoresistance (TMR). As the first magnetic topological materials, MnBi2Te4 hold various magnetic states and thickness-dependent properties rather than single ferromagnetic states, and there are more possibilities to design versatile MTJ devices. Here, we construct the magnetic tunnel junctions based on MnBi2Te4 with Cu as the electrode: Cu/n-Layer-MnBi2Te4/Cu (n = 1, 2, 3, 4) device. Based on density functional theory and nonequilibrium Green’s function, we found that with the thickening of the MnBi2Te4 layers, the spin filtering of MnBi2Te4 is more apparent, where the TMR value at the Fermi level is 100 Schematic view of MnBi2Te4-based device model. The maximum tunnel magnetoresistance (TMR) ratio and the TMR ratio at the Fermi level in Cu/2(4)L-MBT/Cu magnetic tunnel junctions without and with spin–orbit coupling.

By embedding the position disorder of rods in 2D gyromagnetic photonic crystal, the influences of increasing random disorder on the photonic topological phases (PTPs) in a photonic topological insulator are numerically investigated. When the disorder is small, the PTPs almost have no change. With the increase in disorder, the PTPs at the edge of the original topological bandgap are first affected, and those at center of the bandgap have the best robustness. As disorder increases to a critical value, the PTPs collapse ultimately. During the collapse of the PTPs, disorders can induce the Anderson localization of electromagnetic (EM) wave, and produce localized hot spots in the system. When the disorder is not too large, the hot spots are excited at the edge area near the excitation source, and have little influence on the one‐way propagation of the topological edge state (TES). As disorder increases continuously, the hot spots would penetrate the system deeply and affect the propagation of EM waves significantly, which leads to the collapse of the PTPs and destruction of one‐way propagation of TES. Even so, there are still remaining long‐range and short‐range orders in the system. This research provides a theoretical model and an experiment platform for further studying the relationship between topological phases and disorders.

We investigate theoretically the carrier transport in a two-dimensional topological insulator of（001） HgTe/CdTe quantum-well heterostructure with inverted band, and find distinct switchable features of the transmission spectra in the topological edge states by designing the double-electric modulation potentials. The transmission spectra exhibit the significant Fabry–Pérot resonances for the double-electric transport system. Furthermore, the transmission properties show rich behaviors when the Fermi energy lies in the different locations in the energy spectrum and the double-electric barrier regions. The opacity and transparency of the double-modulated barrier regions can be controlled by tuning the modulated potentials, Fermi energy and the length of modulated regions. This electrical switching behavior can be realized by tuning the voltages applied on the metal gates. The Fabry–Pérot resonances leads to oscillations in the transmission which can be observed in experimentally. This electric modulated-mechanism provides us a realistic way to switch the transmission in edge states which can be constructed in low-power information processing devices.

The nonlinear shift current, also known as the bulk photovoltaic current generated by linearly polarized light, has long been known to be absent in crystals with inversion symmetry. Here we argue that a nonzero shift current in centrosymmetric crystals can be activated by a photon-drag effect. Photon-drag shift current proceeds from a "shift current dipole" (a geometric quantity characterizing interband transitions) and manifests a purely transverse response in centrosymmetric crystals. This transverse nature proceeds directly from the shift-vector's pseudovector nature under mirror operation and underscores its intrinsic geometric origin. Photon-drag shift current can be greatly enhanced by coupling to polaritons and provides a new and sensitive tool to interrogate the subtle interband coherences of materials with inversion symmetry previously thought to be inaccessible via photocurrent probes.

Different than covalently bonded magnetic multilayer systems, high-quality interfaces without dangling bonds in van der Waals (vdW) junctions of two-dimensional (2D) layered magnetic materials offer opportunities to realize novel functionalities. Here, we report the fabrication of multi-state vertical spin valves without spacer layers by using vdW homo-junctions in which exfoliated Fe3GeTe2 nanoflakes act as ferromagnetic electrodes and/or interlayers. We demonstrate the typical behavior of two-state and three-state magnetoresistance for devices with two and three Fe3GeTe2 nanoflakes, respectively. Distinct from traditional spin valves with sandwich structures, our novel homo-junction-based spin-valve structure allows the straightforward realization of multi-state magnetic devices. Our work demonstrates the possibility of extend multi-state, non-volatile spin information to 2D magnetic homo-junctions, and it emphasizes the utility of vdW interface as a fundamental building block for spintronic devices.

This work presents theoretically investigate the electron transport through a PN junction in two-dimensional HgTe/CdTe topological insulator. We find that the transmission can be tuned by changing the incidence angle, gate voltage, Fermi energy and the Rashba spin–orbit interaction (RSOI). By tuning the strength of RSOI modulation, the efficient spin-flip conversion for the spin-up and spin-down channels are found. Furthermore, a perfect one-channel transmission mode with T=1 is formed due to the spin-split induced by the RSOI. This RSOI-induced spin-split mechanism provides us a way of pure electrical modulation to manipulate the spin and charge currents.

Controllable construction of graphene into specific architectures at macroscopic scales is crucial for practical applications of graphene. An approach of macroscopic and conductive interconnected graphene networks with controllable patterns, pore, and skeleton sizes via chemical vapor deposition is reported here. Specifically, the pore and skeleton sizes of 3D controllable graphene (3D‐CG) architectures can be tuned from 10 to 50 μm and the orientation angles of building blocks can be designed as 45° and 90°. The electrical conductivity and density of 3D‐CGs are measured at 60–80 S cm−1 and ≈3.6 mg cm−3, respectively. The properties of 3D‐CGs as flexible conductors and supercapacitor electrodes are reported, to explore the potential application in wearable devices and energy store.