In the fields of electrical and optical sciences, transition metal chalcogenides (TMCs) such as PdS, PdSe(2 )and PdTe(2 )have attracted significant attention due to their unique properties. But there are fewer reports on their nonlinear absorption (NLA) properties. In this study, two-dimensional (2D) PdS, PdSe2 , and PdTe(2 )nanosheets were synthesized via the liquid-phase exfoliation (LPE) method. Their broadband NLA responses were systematically investigated using the open-aperture (OA) Z-scan technique. The results revealed that the 2D PdS, PdSe(2 )and PdTe2 nanosheets exhibited pronounced two-photon absorption (TPA) properties from the ultraviolet (UV) to infrared (IR) band. The 2D PdS nanosheets exhibited the strongest TPA properties at the UV band. This superior performance is attributed to its highly symmetric layered structure, weaker spin-orbit coupling (SOC) effect, and lower defect density, which collectively enhance TPA properties. In contrast, PdSe2 and PdTe(2 )show progressively reduced TPA responses. Our results demonstrate that 2D PdS, PdSe(2 )and PdTe(2 )nanosheets possess significant potential as advanced optical limiting (OL) materials.

HfS3 nanosheets were investigated as a nonlinear optical (NLO) material under picosecond laser excitation. Their ultraviolet-to-near-infrared (UV-NIR) nonlinear absorption (NLA) properties were systematically studied using open-aperture (OA) Z-scan technique at 355, 532, and 1064 nm. The results reveal a distinct wavelength- and excitation-energy-dependent response, with two-photon absorption (TPA) becoming dominant at high incident energies. To clarify the origin of the enhanced response, hybrid HSE06 calculations were performed, which indicate that the electronic band distribution and the intrinsic chain-like anisotropy of HfS3 play important roles in promoting nonlinear light-matter interaction. The combined experimental and theoretical results demonstrate that HfS3 nanosheets possess pronounced and competitive NLA activity, especially in the UV band, and suggest their promising potential for optical limiting (OL) and ultrafast photonic protection applications.

Different from the oxidizable peculiarity of black phosphorus nano-material, violet phosphorus (VP) performed preeminent stability, which broadens its application in laser technology field. In this study, passively Q-switched (PQS) solid-state lasers based on Nd:YAG and Pr:YLF laser crystals were successfully demonstrated using VP nanosheets as a saturable absorber (SA). The laser generated pulses with pulse widths of 285.2 ns and a peak power of 2.28 W at 1064 nm, and pulse widths of 279.4 ns with a peak power of 0.55 W at 640 nm. The Qswitched conversion efficiencies were 33% and 17% at 1064 nm and 640 nm, respectively. These findings indicate that VP demonstrates significant laser modulation capabilities in both the near-infrared and visible spectral ranges, offering valuable insights for the development of novel high-performance SAs.

As promising layered semiconductors, two-dimensional (2D) SnS2 and Janus SnSSe exhibit diverse nonlinear optical (NLO) behaviors that are strongly influenced through structural modulation. In this study, the nonlinear absorption (NLA) responses of both materials were systematically investigated using the open aperture (OA) Zscan technique under excitation wavelengths of 355, 532, and 1064 nm. The results indicated that both materials exhibit two-photon absorption (TPA) as the dominant mechanism at high excitation energies. Notably, SnS2 still exhibited TPA as the dominant mechanism at low excitation energies, while SnSSe showed saturated absorption (SA) across all three wavelengths (355, 532, and 1064 nm). Structural analysis revealed that the introduction of Se transforms the point group from the centrosymmetric D3d to the non-centrosymmetric C3v, breaking inversion symmetry and altering the electronic state distribution and transition selection rules, thereby enhancing the SA behavior of SnSSe. These findings underscore the critical role of anion substitution in modulating the NLO properties of 2D materials, providing valuable insights for the development of advanced optical limiting (OL) devices and saturable absorbers.

Room-temperature sodium-sulfur batteries receive widespread attention due to their high theoretical energy density, low cost, and resource abundance. However, at room temperature, sodium-sulfur batteries face key challenges such as low cathode sulfur conversion efficiency, serious polysulfide shuttle effect, sodium anode dendrite growth, and poor electrolyte stability. To address these issues, extensive research has been devoted to the design of functional materials aimed at enhancing battery performance. This paper summarizes the working principle of room-temperature sodium-sulfur battery, elucidates the mechanisms by which these materials enhance sulfur utilization and suppress polysulfide diffusion. Finally, it discusses current challenges and future development directions, aiming to promote further performance enhancement of room-temperature sodium-sulfur batteries.

The direct and rapid growth of graphene on insulating substrates holds immense significance for various applications, such as optoelectronics and sensors. Here, we report the low-pressure chemical vapor deposition (LPCVD) growth of large-area, high-quality graphene on quartz using isopropanol as carbon source. The technique facilitates the rapid deposition of graphene onto transparent quartz substrates, thereby favouring their application in optoelectronic devices. The deposition time for a monolayer graphene film covering the substrate surface is approximately one minute. The prepared graphene films exhibit exceptional surface uniformity, high light transmission and polarization-depedent absorption properties. Moreover, the polarisation absorption properties of graphene have been utilized in sensitive ultrasonic detection. Ultrasonic waves induce changes in the refractive index of the liquid medium, leading to disturbances in the polarisation state and reflected light power from the liquid-quartz interface. This work offers a simple method for large-area graphene growth, explores its use in ultrasonic detection, and will advances graphene's application in cutting-edge technologies.

MXenes, as emerging class of two-dimensional (2D) materials, has garnered considerable attention in both optical and electrical domains. In this study, the MXene (V2C) was synthesized by etching the MAX-phase precursor (V2AlC) using a mixture of hydrofluoric acid (HF) and hydrochloric acid (HCl), followed by intercalation with tetrabutylammonium hydroxide solution (TBAH). Furthermore, V2AlC and V2C nanosheets were fabricated via the liquid-phase exfoliation (LPE) method, and their nonlinear absorption (NLA) properties were systematically investigated across the ultraviolet (UV) to short-wave infrared (SWIR) band. The results demonstrated that 2D V2AlC nanosheets exhibited higher two-photon absorption (TPA) coefficients (beta), lower OL thresholds, and larger TPA cross sections (sigma TPA) in the SWIR band. In contrast, V2C nanosheets, formed after etching, exhibited superior TPA performance in the UV band, displaying distinctly different nonlinear optical (NLO) behaviors. These findings suggest that both materials possess outstanding optical limiting (OL) performance, with each material offering distinct advantages at specific wavelengths. Overall, V2AlC and V2C nanosheets hold great promise as advanced OL materials for applications in optical component protection, laser protection for the human eye, and optical filtering.

The tunable geometrical properties of gold nanoparticles (AuNPs) endow them with the capacity to exhibit distinct behaviors with respect to both macroscopic (color) and microscopic (resonance wavelength) aspects, which has been extensively utilized in localized surface plasmon resonance (LSPR) sensing platforms. Additionally, functionalizing AuNP surfaces enhances the platforms' capabilities, allowing for the detection of a wide range of molecules related to various aspects of human health. In this review, we comprehensively elucidate the fundamental principles of LSPR biosensing and provide an in-depth survey of the preparation processes for metal nanoparticles, encompassing deposition technology for large-scale particle production as well as ion reduction methods that afford superior control over the particles' physical and chemical attributes. The sensing strategies based on adjustment of the dielectric environment and particle dispersion-aggregation levels are thoroughly reviewed and discussed. The discussion focused on a specific class of nanoparticles, characterized by their uniform shape and size, with each section bifurcated into two parts: a summary of the salient features and recent discoveries pertaining to the sensing strategy, as well as illustrations of representative, cutting-edge applications employing the strategy. We specifically aim to scrutinize analytes commonly encountered in the biomedical realm, encompassing biomarkers that serve as indicators of a wide range of diseases and microbial pathogens, while also prognosticating the future development trends of LSPR optical biosensor platforms within the biomedical field.

Transition-metal gallium sulfide (GaS) and gallium selenide (GaSe), which belong to the binary IIIA-VIA group of compounds, have garnered significant attention, primarily due to their distinctive optoelectronic properties. In this study, GaS and GaSe nanosheets were synthesized using the liquid phase exfoliation method, and their nonlinear absorption characteristics from ultraviolet to near-infrared spectral ranges were investigated through open-aperture Z-scan measurements. The results revealed that GaS and GaSe nanosheets exhibited versatile nonlinear properties in various wavebands. Specifically, they both possessed exceptional nonlinear absorption properties in the ultraviolet band. Furthermore, GaS nanosheets exhibited superior two-photon absorption behavior at 1064 nm and outstanding saturation absorption property at 355 nm compared with the same excitation of GaSe nanosheets. These versatile nonlinear properties highlight the substantial potential of layered GaS and GaSe nanosheets in driving the progression of sophisticated nanophotonic devices, including mode-locking in the ultraviolet waveband and optical limiters in the infrared waveband.

As transition metal dichalcogenides (TMDCs), PtSe2 and PtTe2 exhibit promising nonlinear optical (NLO) properties but lack systematic studies on their nonlinear absorption (NLA) properties. Given that PtSe2 and PtTe2 possess an identical hexagonal crystal structure. In this study, we systematically evaluate their NLO properties using open-aperture (OA) Z-scan technique performed at wavelengths of 355, 532, and 1064 nm. Both materials showed significant two-photon absorption (TPA), with their TPA cross-sections (sigma(TPA)) increasing trend as decreasing wavelength. The sigma(TPA) of two-dimensional (2D) PtTe2 exhibited around one order of magnitude larger than that of 2D PtSe2 in the ultraviolet (UV) band (355 nm), particularly, indicating a stronger optical limiting (OL) effect. Considering that the structural difference between the two materials primarily arises from anion substitution, we further investigated the superior OL performance of 2D PtTe2 from the perspective of band structure. This analysis elucidates the underlying physical mechanism associated with band splitting induced by spin-orbit coupling (SOC) effects. This study not only advances TMDCs as promising candidates for high-power laser protection, OL devices, and UV photodetection in the NLO field. It also offers valuable insights for the design and development of high-performance NLO materials.

Black phosphorus (BP) has attracted much attention due to its distinctive band-gap properties and strong light-matter interaction, which make it a promising nonlinear optical material. In this study, BP nanosheets were exfoliated successfully utilizing the liquid phase exfoliation technique. Using an open-aperture Z-scan method, the broadband nonlinear absorption characteristics of BP nanosheets were studied. Under 355 nm excitation, the BP nanosheets demonstrated pronounced saturation absorption properties, with the maximum normalized transmittance of the wave peaks reaching 149% at an excitation energy of 7μJ. Moreover, the threshold for nonlinear absorption behavior in BP nanosheets at 355 nm was approximately 0.023 GW cm-2.The results showed that BP nanosheets possess strong saturable absorption properties in ultraviolet (UV) waveband. The saturable absorption characteristics of BP nanosheets make it possible to apply it in UV laser as saturable absorber, which can broaden its application in UV nonlinear optics.

As fast-emerging two-dimensional (2D) materials, MXenes have attracted great attention in the fields of optics and electricity. In this paper, the nonlinear optical (NLO) properties of the 2D MXene material (Nb4C3) and its MAX predecessor (Nb4AlC3) are presented. Also, the broadband NLO responses of Nb4AlC3 and Nb4C3 nanosheets had been investigated using the open aperture (OA) Z-scan technique. The results showed that 2D Nb4AlC3 exhibited significant two-photon absorption (TPA) properties in the short-wave infrared (SWIR) band. Different from Nb4AlC3, its etching residue, Nb4C3, exhibited totally opposite NLO behavior, which showed superior TPA properties in the ultraviolet (UV) band. This implied that the optical limiting (OL) properties of these two materials were exactly opposite. In the future, 2D Nb4AlC3 and Nb4C3 will be expected to be used as OL materials in the UV and SWIR bands, respectively, for such applications as laser protection, human eye protection, making optical filters, etc. Our work expanded a great potential application of 2D MXenes materials in the broadband nonlinear optical photonics.

Lithium–sulfur batteries (LSB) have been recognized as a prominent potential next-generation energy storage system, owing to their substantial theoretical specific capacity (1675 mAh g−1) and high energy density (2600 Wh kg−1). In addition, sulfur’s abundance, low cost, and environmental friendliness make commercializing LSB feasible. However, challenges such as poor cycling stability and reduced capacity, stemming from the formation and diffusion of lithium polysulfides (LiPSs), hinder LSB’s practical application. Introducing functional separators represents an effective strategy to surmount these obstacles and enhance the electrochemical performance of LSBs. Here, we have conducted a comprehensive review of recent advancements in functional separators for LSBs about various (i) carbon and metal compound materials, (ii) polymer materials, and (iii) novel separators in recent years. The detailed preparation process, morphology and performance characterization, and advantages and disadvantages are summarized, aiming to fundamentally understand the mechanisms of improving battery performance. Additionally, the development potential and future prospects of advanced separators are also discussed.

MXenes have important research value in the field of photonics. In this work, Ti3C2 MXene was obtained by etching the Ti3AlC2 MAX phase with hydrofluoric acid, Ti3AlC2 and Ti3C2 nanosheets with a thickness of several nanometers were prepared by ultrasound-assisted liquid-phase exfoliation using anhydrous ethanol as the exfoliation solvent. The nonlinear absorption properties of the two nanosheets at 1064, 532 and 355 nm excitation wavelengths (infrared to ultraviolet band), especially the optical limiting behavior, were systematically investigated with the help of open aperture Z-scan technique. Interestingly, Ti3C2 MXene, obtained from Ti3AlC2 MAX by a simple hydrofluoric acid etching operation only, exhibits different nonlinear optical properties from Ti3AlC2 MAX under the same experimental conditions. Ti3AlC2 nanosheets exhibited excellent two-photon absorption behavior in the visible light band, while the two-photon absorption behavior of Ti3C2 nanosheets is better in the ultraviolet band. The excellent nonlinear absorption properties exhibited by Ti3AlC2 and Ti3C2 nanosheets demonstrate their advantages as OL materials with great potential for applications in laser protection.

Rechargeable lithium-oxygen (Li-O-2) batteries are known for their ultrahigh theoretical energy density among chemical batteries. However, the low catalytic activity and poor stability of the cathode catalyst are the root issues limiting their practical applications. In this work, a design strategy to enhance the catalytic activity of the TiC material was devised by C surface modification. The carbon-coated core-shell TiC@C nanomaterial was designed, which combined the good electrical conductivity and low density of carbon materials with the excellent catalysis of TiC. The calculated catalytic activities of TiC (100) with and without C coating were compared by first-principles calculations, showing that the TiC (100)@C surface has a lower ORR/OER overpotential. The C layer enhances the conductivity of the TiC (100) surface significantly. This work fully demonstrates the synergistic catalysis of TiC material and C coating, which not only effectively accelerates the practical process by improving the charging and discharging kinetic rate of Li-O-2 batteries but also provides an efficient catalyst design strategy for other energy-catalytic industries.

The violet phosphorus is a layered semiconductor material possessing a diverse range of exceptional physical properties. Until now, the nonlinear optical properties of violet phosphorus nanomaterials have been relatively scarce, and most of them were limited in the exploration of one single wavelength. In contrast, our study was based on the broadband nonlinear absorption characteristics of violet phosphorus nanomaterials from the ultraviolet to near-infrared waveband. In this paper, the two-dimensional violet phosphorus nanosheets were prepared by using the liquid-phase exfoliation method. The broadband (from ultraviolet to near-infrared) nonlinear optical properties of the two-dimensional violet phosphorus nanosheets were investigated by the open-aperture Z-scan method. And the band gap values of the two-dimensional violet phosphorus were analyzed through experimental characterization and density-functional theory. The experimental results show that the two-dimensional VP nanosheets exhibit saturable and two-photon absorption. In the ultraviolet band, the two-dimensional violet phosphorus nanosheets exhibit the most excellent saturable absorption properties. This work had important implications in the fields of ultrafast lasers, microfabrication, nanofabrication, and optical limiting fields.

Under the threat of the two major dilemmas of energy scarcity and environmental degradation, the development of sustainable, clean, and efficient energy sources has become increasingly urgent. In recent years, electrocatalytic hydrogen evolution reaction (HER) has become a promising method for the preparation of energy sources for sustainable hydrogen production. However, the monolithic nature of the active site/active phase of metallic transition metal disulfides (MTMDs) limits the performance of HER to that of commercial Pt/C catalysts. Herein, we report the hydrothermal growth of VS2/Ti3C2 heterogeneous structure on MXene substrates for the first time. The VS2/Ti3C2 heterogeneous structure exhibits extremely high catalytic activity and electrochemical durability. Exhibiting an overpotential of only 33 mV and a Tafel slope of 25.93 mV dec(-1) in 0.5 M H2SO4 acidic electrolyte, the catalysts showed excellent durability over 24 h and near 100% Faraday efficiency. Meanwhile, the formation of heterogeneous structure was also demonstrated by both X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) data. Theoretical studies confirmed that the successful construction of Ti-S bonds in VS2/Ti3C2 heterogeneous structure accelerates the charge transfer rate, which modifies the electrical properties of VS2 nanoflowers and the hydrogen adsorption properties at the Ti-edge and the S-edge. This work accelerated the charge transfer rate of the electrocatalyst through the formation of a heterogeneous structure between VS2 and Ti3C2, providing a strategy for highly efficient electrocatalytic hydrogen evolution reaction.

Two-dimensional (2D) materials have drawn more attention since the discovery of graphene. The exploration of the nonlinear optical (NLO) properties of 2D materials has become more urgent. In this work, Ti4AlN3 nanosheets with a thickness of about 1.7–1.9 nm were prepared using the liquid phase exfoliation (LPE) method, and the open aperture (OA) Z-scan technique was used to explore the broadband nonlinear absorption (NLA) properties of 2D Ti4AlN3 nanosheets at three wavelengths, namely, 355, 532, and 1064 nm. According to the results, 2D Ti4AlN3 nanosheets exhibited excellent optical limiting (OL) behavior in all three bands, especially in the infrared (IR) band. The large two-photon absorption (TPA) coefficient and low OL excitation threshold indicated that Ti4AlN3 had great potential as OL material in the IR band for applications such as optical filters, protection of the human eye, laser protection, etc.