Millisecond laser ablation of molybdenum target in reactive gas toward MoS2 fullerene-like nanoparticles with thermally stable photoresponse

Fullerene-like MoS2 Nanoparticles as Cascade Catalysts Improving Lubricant and Antioxidant Abilities of Artificial Synovial Fluid

Intraarticular injection of hyaluronic acid (HA) for viscosupplementation is a nonsurgical therapy for osteoarthritis (OA). However, HA fails to lubricate under a significant load and tends to be depolymerized by the overproduction of reactive oxygen species (ROS) in inflammation. Here, we for the first time reported that fullerene-like MoS₂ (F-MoS₂) nanoparticles are efficient lubricants and antioxidants for artificial synovial fluid. A model of arthrosis was built, to evaluate the tribological behavior of F-MoS₂ nanoparticles. The tests showed that they significantly improve the antiwear and friction-reducing abilities of the artificial synovial fluid. More importantly, the F-MoS₂ nanoparticles possess intrinsic dual-enzyme-like activity, mimicking superoxide dismutases (SOD) and catalases (CAT) under physiological conditions (pH 7.4, 25 °C). By coupling of these unique properties, a self-organized cascade catalytic system was constructed, which includes the disproportionation of superoxide radicals (O₂^•-) to hydrogen peroxide (H₂O₂) and subsequently the disproportionation of H₂O₂ into oxygen (O₂). The effectiveness of the detox system was evaluated by human umbilical vein endothelial cells (HUVEC) models exposed to oxidative stress. After that, F-MoS₂ nanoparticles were used to regulate the ROS level in artificial synovial fluid containing HA. Relative viscosity measurements showed the excellent protective effect of F-MoS₂ nanoparticles against HA oxidative damage offered by O₂^•-. These results indicate that F-MoS₂ nanoparticles are promising candidates for treatment of OA and other diseases caused by lubrication deficiency or oxidative stress.

Alloying-assisted phonon engineering of layered BiInSe3@nickel foam for efficient solar-enabled water evaporation

The fresh water crisis has emerged as one of the most urgent bottlenecks hindering the rapid development of modern industry and society. Solar energy-driven water evaporation represents a potential green and sustainable solution to address this issue. Herein, for the first time, centimeter-scale BiInSe₃-coated nickel foam (BiInSe₃@NF) as an efficient solar-enabled evaporator was successfully achieved and exploited for solar energy-driven water evaporation. Benefitting from multiple scattering-induced light trapping of the rough substrate, strong light-matter interaction and intermediate band (IB)-induced efficient phonon emission of BiInSe₃, the BiInSe₃@NF device achieved a high evaporation rate of 0.83 kg m^-2 h^-1 under 1 sun irradiation, which is 2.5 times that of pure water. These figures-of-merit are superior to recently reported state-of-the-art photothermal conversion materials, such as black titania, plasmonic assembly and carbon black. In addition, superior stability over a period of 60 days was demonstrated. In summary, the current contribution depicts a facile scenario for design, production and application of an economical and efficient solar-enabled BiInSe₃@NF evaporator. More importantly, the phonon engineering strategy based on alloying induced IB states can be readily applied to other analogous van der Waals materials and a series of superior vdWM alloys toward photothermal applications can be expected in the near future.

Emerging 0D Transition-Metal Dichalcogenides for Sensors, Biomedicine, and Clean Energy

Following research on two-dimensional (2D) transition metal dichalcogenides (TMDs), zero-dimensional (0D) TMDs nanostructures have also garnered some attention due to their unique properties; exploitable for new applications. The 0D TMDs nanostructures stand distinct from their larger 2D TMDs cousins in terms of their general structure and properties. 0D TMDs possess higher bandgaps, ultra-small sizes, high surface-to-volume ratios with more active edge sites per unit mass. So far, reported 0D TMDs can be mainly classified as quantum dots, nanodots, nanoparticles, and small nanoflakes. All exhibited diverse applications in various fields due to their unique and excellent properties. Of significance, through exploiting inherent characteristics of 0D TMDs materials, enhanced catalytic, biomedical, and photoluminescence applications can be realized through this exciting sub-class of TMDs. Herein, we comprehensively review the properties and synthesis methods of 0D TMDs nanostructures and focus on their potential applications in sensor, biomedicine, and energy fields. This article aims to educate potential adopters of these excitingly new nanomaterials as well as to inspire and promote the development of more impactful applications. Especially in this rapidly evolving field, this review may be a good resource of critical insights and in-depth comparisons between the 0D and 2D TMDs.

Au@MoS2 Core-Shell Heterostructures with Strong Light-Matter Interactions

There are emerging opportunities to harness diverse and complex geometric architectures based on nominal two-dimensional atomically layered structures. Herein we report synthesis and properties of a new core-shell heterostructure, termed Au@MoS₂, where the Au nanoparticle is snugly and contiguously encapsulated by few shells of MoS₂ atomic layers. The heterostructures were synthesized by direct growth of multilayer fullerene-like MoS₂ shell on Au nanoparticle cores. The Au@MoS₂ heterostructures exhibit interesting light-matter interactions due to the structural curvature of MoS₂ shell and the plasmonic effect from the underlying Au nanoparticle core. We observed significantly enhanced Raman scattering and photoluminescence emission on these heterostructures. We attribute these enhancements to the surface plasmon-induced electric field, which simulations show to mainly localize within the MoS₂ shell. We also found potential evidence for the charge transfer-induced doping effect on the MoS₂ shell. The DFT calculations further reveal that the structural curvature of MoS₂ shell results in a modification of its electronic structure, which may facilitate the charge transfer from MoS₂ to Au. Such Au@MoS₂ core-shell heterostructures have the potential for future optoelectronic devices, optical imaging, and other energy-environmental applications.

Layered and Pb-Free Organic-Inorganic Perovskite Materials for Ultraviolet Photoresponse: (010)-Oriented (CH3NH3)2MnCl4 Thin Film

Organic-inorganic lead perovskite materials show impressive performance in photovoltaics, photodetectors, light-emitting diodes, lasers, sensors, medical imaging devices, and other applications. Although organic-inorganic lead perovskites have shown good performance in numerous fields, they contain toxic Pb, which is expected to cause environmental pollution in future large-scale applications. Thus, the photoelectric properties of Pb-free organic-inorganic perovskite materials should be developed and studied. In this paper, we report on the photoresponse of Pb-free organic-inorganic hybrid manganese perovskite (CH₃NH₃)₂MnCl₄. To the best of our knowledge, this study demonstrates the first time that organic-inorganic hybrid manganese perovskites are used for this type of application. We found that the solution-processed MA₂MnCl₄ thin film tends to be oriented along the b-axis direction on the TiO₂ surface. The evident photoresponse of the FTO/TiO₂/MA₂MnCl₄/carbon electrode devices was observed under 10-30 Hz flashlight frequencies and a 330 nm light beam. This simple, green, and low-cost photoresponsive device is beneficial for the future industrial production of optical recorders and optical memory devices.

Promoting the Performance of Layered-Material Photodetectors by Alloy Engineering

The successful peeling of graphene heralded the era of van der Waals material (vdWM) electronics. However, photodetectors based on semiconducting transition metal dichalcogenides (TMDs), formulated as MX2 (M = Mo, W; X = S, Se), often suffer either poor responsivity or long response time because of their high density of deep-level defect states (DLDSs). Alloy engineering, which can shift the DLDSs to shallow-level defect states, is proposed to be an efficient strategy to solve this problem. However, proof-of-concept is still lacking, which is probably because of the absence of a facile technology to grow high-quality alloyed TMDs. Here, we report the growth of large-scale and high-quality Mo0.5W0.5S2 alloy films via pulsed laser deposition (PLD). We demonstrate that the resulting Mo0.5W0.5S2 photodetector possesses a stable photoresponse from 370 to 1064 nm. The photocurrent exhibits positive dependence on both the source-drain voltage and incident power density, providing good tunability for multifunctional photoelectrical applications. We also establish that, because of the suppression of DLDSs with alloy engineering, the Mo0.5W0.5S2 photodetector achieves a good responsivity of 5.8 A/W and a response time shorter than 150 ms. The working mechanism for the suppression of DLDSs in Mo0.5W0.5S2 is unveiled by qualitatively analyzing the alloying-dressed band structure. In conclusion, the excellent performance of the PLD-grown Mo0.5W0.5S2 photodetector may pave the way for next-generation photodetection. The approach shown here represents a fundamental and universal scenario for the development of alloyed TMDs.