Nanoscale最新文献

Titanium (Ti) alloys have low thermal conductivity, suffer from tool wear and deformation of workpieces and are difficult-to-machine metals. This contributes to surface roughness, S_a > 240 nm of Ti alloys after mechanical polishing with a low material removal rate (MRR). With the addition of assisting energy fields, the MRR is usually lower than 7 μm h^-1. Nevertheless, there is a high demand to achieve S_a < 50 nm on a free surface blade to save energy and reduce the resistance of fluids. To address this challenge, novel photocatalytic shear-thickening chemical mechanical polishing (PSTCMP) was developed using a custom-made polisher. The new PSTCMP slurry contained ceria, corn starch, sodium bicarbonate and deionized water. After PSTCMP, the S_a and thickness of the damaged layer of a free surface blade of a Ti alloy decreased from 501.71 to 38.46 nm and from 634.79 to 7.83 nm, respectively, representing reductions of 92% and 99%. The MRR is 12.52 μm h^-1. To the best of our knowledge, both the S_a and MRR are the best published to date for a Ti alloy blade with a free surface. PSTCMP mechanisms were interpreted using first-principles molecular dynamics, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Hydroxyl radicals were generated under ultraviolet irradiation on ceria with a size of 4.2 nm, oxidizing the surface of the Ti alloy and forming Ti-OH and Ti-O groups. A Ce-O-Ti interface bridge was produced between Ti-OH and Ce-OH, induced by the hydrolysis of ceria. Our findings provide a new way to fabricate nanometer-scale surface roughness on a free surface blade of a Ti alloy with a high MRR.

Encapsulation protects functional layers, ensuring structural stability and improving the quality of assembled van der Waals heterostructures. Here, we develop a model that describes lattice relaxation in twisted bilayers accounting for encapsulation effects, incorporated via a single parameter characterizing the rigidity of encapsulation material interfaces. By analysing the twist-angle dependence of weak-to-strong lattice relaxation transition in twisted transition metal dichalcogenide bilayers, we show that increasing interface rigidity raises the crossover twist angle between the two relaxation regimes. Furthermore, tuning this rigidity parameter allows achieving good agreement with existing experimental results.

Global water security faces dual challenges of increasing scarcity and persistent pollution. This review clarifies its focus by positioning metal-organic frameworks (MOFs) within the frameworks of environmental sustainability, the circular water economy, and life cycle assessment (LCA). While MOFs offer surface areas typically exceeding 1000 m² g^-1 and tunable porosity for adsorption and desalination, their transition to real-world application is limited by critical engineering hurdles. The scope of this work is explicitly defined by evaluating: (1) MOFs' role in addressing water scarcity; (2) their environmental and economic viability via LCA data; and (3) the identification of barriers to industrial deployment, including raw material costs, regulatory hurdles, and disposal risks. By synthesizing specific examples such as frameworks maintaining stability for 100 days in saline environments and systems targeting energy consumption below 1.0 kWh m^-3 this review identifies the hydrothermal stability benchmarks and total cost of ownership (TCO) hurdles that must be overcome for large-scale commercialization. The focus remains on bridging the gap between laboratory-scale innovation and the practical requirements of sustainable water purification infrastructure.