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Rational design of unique pre‐catalysts for highly active catalysts toward catalyzing the oxygen evolution reaction (OER) is a great challenge. Herein, a Co‐derived pre‐catalyst that allows gradual exposure of CoOOH that acts as the active center for OER catalysis is obtained by both phosphate ion surface functionalization and Mo inner doping. The obtained catalyst reveals an excellent OER activity with a low overpotential of 265 mV at a current density of 10 mA cm−2 and good durability in alkaline electrolyte, which is comparable to the majority of Co‐based OER catalysts. Specifically, the surface functionalization produces lots of Co‐PO4 species with oxygen vacancies which can trigger the surface self‐reconstruction of pre‐catalyst for a favorable OER reaction. Density functional theory calculations reveal that the Mo doping optimizes adsorption‐free energy of *OOH formation and thus accelerates intrinsic electrocatalytic activity. Expanding on these explorations, a series of transition metal oxide pre‐catalysts are obtained using this general design strategy. The work offers a fundamental understanding toward the correlation among surface‐structure‐activity for the pre‐catalyst design. Unravelling the intrinsic mechanism, especially what the “true” catalyst for the oxygen evolution reaction (OER) is, is still highly challenging. Herein, a Co‐based pre‐catalyst is designed that enables rational control over exposure of true active CoOOH centers by in situ self‐reconstruction to deliver excellent electrocatalytic performance, representing one of the state‐of‐the‐art OER catalysts.

Breaking down barriers Topological states have become the subject of much attention from condensed-matter physicists, as evidence accumulates to show that these states can be found on the surface of certain materials — in particular, bulk compounds called topological insulators. As a product of their topological nature, topological surface states are predicted to have the remarkable property of being robust against imperfections. This can allow, for example, the conduction of electronic currents without dissipation. Ali Yazdani and his team now report a tantalizing finding from scanning tunnelling microscope measurements — that topological surface states on antimony can be transmitted with high probability through naturally occurring barriers that stop other conventional surface states of common metals. The authors suggest that their findings indicate that topological surface states could be exploited in novel applications of nanoscale electronic devices. Topological surface states are a class of electronic states that might be of interest in quantum computing or spintronic applications. They are predicted to be robust against imperfections, but so far there has been no evidence that these states do transmit through naturally occurring surface defects. Here, scanning tunnelling microscopy has been used to show that topological surface states of antimony can be transmitted through naturally occurring barriers that block non-topological surface states of common metals. Topological surface states are a class of novel electronic states that are of potential interest in quantum computing or spintronic applications 1 , 2 , 3 , 4 , 5 , 6 , 7 . Unlike conventional two-dimensional electron states, these surface states are expected to be immune to localization and to overcome barriers caused by material imperfection 8 , 9 , 10 , 11 , 12 , 13 , 14 . Previous experiments have demonstrated that topological surface states do not backscatter between equal and opposite momentum states, owing to their chiral spin texture 15 , 16 , 17 , 18 . However, so far there is no evidence that these states in fact transmit through naturally occurring surface defects. Here we use a scanning tunnelling microscope to measure the transmission and reflection probabilities of topological surface states of antimony through naturally occurring crystalline steps separating atomic terraces. In contrast to non-topological surface states of common metals (copper, silver and gold) 19 , 20 , 21 , 22 , 23 , which are either reflected or absorbed by atomic steps, we show that topological surface states of antimony penetrate such barriers with high probability. This demonstration of the extended nature of antimony’s topological surface states suggests that such states may be useful for high current transmission even in the presence of atomic-scale irregularities—an electronic feature sought to efficiently interconnect nanoscale devices.

This article presents an analysis of the impact of vibratory shot peening on the surface roughness and physical properties of the Ti6Al4V titanium alloy surface layer after milling. The elements of machine parts and structures made of titanium alloys are often exposed to variable loads during operation. Therefore, it is advisable to apply methods that enhance functional properties and increase the durability of interacting components. Increasing the operational durability of such elements can be achieved by vibratory shot peening. Variable amplitudes A = 24; 33; 42; 51; 60 mm and times t = 1; 7; 13; 19; 25 min were applied. It has been demonstrated that it is possible to achieve a threefold reduction in the roughness parameter, Sa = 0.344 µm, compared with milling, Sa = 0.95 µm. An increase in Smr(c) areal material ratio was observed after vibratory shot peening compared with milling. It has been shown that amplitude has a greater impact on the increase in hardening of the surface layer gh compared with time. The highest rate of change in surface roughness and thickness of the hardened layer was achieved at a vibratory shot-peening time of t = 13 min. The greatest thickness of the hardened layer, exceeding 200 µm, was obtained after shot peening with an amplitude of A = 60 mm.

HighlightsInspired by the Chinese Knotting weave structure, an electromagnetic interference (EMI) nanofiber composite membrane with a twill surface was prepared.The EMI shielding efficiency (SE) of the composite membrane was 103.9 dB when the MXene/silver nanowires (MXene/AgNW) content was only 7.4 wt% and the surface twill structure improved the EMI by 38.5%.The nanofiber composite membrane demonstrated an excellent thermal management performance, hydrophobicity, non-flammability, and performance stability, which was demonstrated by an EMI SE of 97.3% in a high-temperature environment at 140 °C.Inspired by the Chinese Knotting weave structure, an electromagnetic interference (EMI) nanofiber composite membrane with a twill surface was prepared. Poly(vinyl alcohol-co-ethylene) (Pva-co-PE) nanofibers and twill nylon fabric were used as the matrix and filter templates, respectively. A Pva-co-PE-MXene/silver nanowire (Pva-co-PE-MXene/AgNW, PMxAg) membrane was successfully prepared using a template method. When the MXene/AgNW content was only 7.4 wt% (PM7.4Ag), the EMI shielding efficiency (SE) of the composite membrane with the oblique twill structure on the surface was 103.9 dB and the surface twill structure improved the EMI by 38.5%. This result was attributed to the pre-interference of the oblique twill structure in the direction of the incident EM wave, which enhanced the probability of the electromagnetic waves randomly colliding with the MXene nanosheets. Simultaneously, the internal reflection and ohmic and resonance losses were enhanced. The PM7.4Ag membrane with the twill structure exhibited both an outstanding tensile strength of 22.8 MPa and EMI SE/t of 3925.2 dB cm−1. Moreover, the PMxAg nanocomposite membranes demonstrated an excellent thermal management performance, hydrophobicity, non-flammability, and performance stability, which was demonstrated by an EMI SE of 97.3% in a high-temperature environment of 140 °C. The successful preparation of surface-twill composite membranes makes it difficult to achieve both a low filler content and a high EMI SE in electromagnetic shielding materials. This strategy provides a new approach for preparing thin membranes with excellent EMI properties.

Femtosecond (fs) laser processing has received great attention for preparing novel micro-nano structures and functional materials. However, the induction mechanism of the micro-nano structures induced by fs lasers still needs to be explored. In this work, the laser-induced periodic surface structure (LIPSS) of monocrystalline silicon (Si) under fs laser irradiation is investigated. Three different layers named amorphous silicon (a-Si) layer, transition layer, and unaffected Si layer are observed after laser irradiation. The a-Si layer on the surface is generated by the resolidification of melting materials. The unaffected Si layer is not affected by laser irradiation and maintains the initial atomic structure. The transition layer consisting of a-Si and unaffected Si layers was observed under the irradiated subsurface. The phase transition mechanism of Si irradiated by fs laser is “amorphous transition”, with the absence of other crystal structures. A numerical model is established to describe the fs laser-Si interaction to characterize the electronic (lattice) dynamics of the LIPSS formation. The obtained results contribute to the understanding of fs laser processing of Si at the atomic scale as well as broaden the application prospects of fs laser for treating other semiconductor materials.

Laser-induced periodic surface structures (LIPSS) are a simple and robust route for the nanostructuring of solids that can create various surface functionalities featuring applications in optics, medicine, tribology, energy technologies, etc. While the current laser technologies already allow surface processing rates at the level of m2/min, industrial applications of LIPSS are sometimes hampered by the complex interplay between the nanoscale surface topography and the specific surface chemistry, as well as by limitations in controlling the processing of LIPSS and in the long-term stability of the created surface functions. This Perspective article aims to identify some open questions about LIPSS, discusses the pending technological limitations, and sketches the current state of theoretical modelling. Hereby, we intend to stimulate further research and developments in the field of LIPSS for overcoming these limitations and for supporting the transfer of the LIPSS technology into industry.

Highlights We propose the novel concept of a tough hydrogel scaffold within the realm of tissue engineering. This scaffold combines exceptional strength (6.66 MPa), customization capabilities, and superior biocompatibility in a manner not previously achieved in existing research. These tough hydrogel scaffolds possess functional surface structures and can effectively enhance cell-guided growth and prompt regeneration of muscle tissue in vivo. This is a universal manufacturing method for tough hydrogel scaffolds in tissue engineering. Hydrogel scaffolds have numerous potential applications in the tissue engineering field. However, tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical properties. Inspired by Chinese ramen, we propose a universal fabricating method (printing-P, training-T, cross-linking-C, PTC & PCT) for tough hydrogel scaffolds to fill this gap. First, 3D printing fabricates a hydrogel scaffold with desired structures (P). Then, the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance (T). Finally, the training results are fixed by photo-cross-linking processing (C). The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa (622-fold untreated) and have excellent biocompatibility. Furthermore, this scaffold possesses functional surface structures from nanometer to micron to millimeter, which can efficiently induce directional cell growth. Interestingly, this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt, and many hydrogels, such as gelatin and silk, could be improved with PTC or PCT strategies. Animal experiments show that this scaffold can effectively promote the new generation of muscle fibers, blood vessels, and nerves within 4 weeks, prompting the rapid regeneration of large-volume muscle loss injuries.

Near-surface structure investigation plays an important role in studying shallow active faults and has various engineering applications. Therefore, we developed a near-surface structure investigation method using ambient noise in a water environment. This newly developed seismic acquisition technology, fiber-optic distributed acoustic sensing (DAS), was used to acquire ambient noise from the Yangtze River. The recorded data were processed to reconstruct surface waves based on the theory of seismic interferometry. The fundamental-mode dispersion curves were extracted and inverted to obtain a shear-wave velocity model below the DAS line. We compared the inverted velocity model with the subsurface geological information from near the study area. The results from the inverted model were consistent with the prior geological information. Therefore, ambient noise in the water environment can be combined with DAS technology to effectively investigate near-surface structures.

Hard and brittle materials have high hardness, excellent optical stability, chemical stability, and high thermal stability. Hence, they have huge application potential in various fields, such as optical components, substrate materials, and quantum information, especially under harsh conditions, such as high temperatures and high pressures. Femtosecond laser direct writing technology has greatly promoted the development of femtosecond laser-induced periodic surface structure (Fs-LIPSS or LIPSS by a femtosecond laser) applications of hard and brittle materials due to its high precision, controllability, and three-dimensional processing ability. Thus far, LIPSSs have been widely used in material surface treatment, optoelectronic devices, and micro-mechanics. However, a consensus has not been reached regarding the formation mechanism of LIPSSs on hard and brittle materials. In this paper, three widely accepted LIPSS formation mechanisms are introduced, and the characteristics and applications of LIPSSs on diamonds, silicon, silicon carbide, and fused silica surfaces in recent years are summarized. In addition, the application prospects and challenges of LIPSSs on hard and brittle materials by a femtosecond laser are discussed.

Rainfall can wash the surface atmospheric particulate matter (PM) into the soil, and restore the PM retention function of the turfgrass blades. The dynamic process of PM removal on turfgrass blades concerning rainfall intensity and duration was investigated, and the relationship between rainfall, leaf surface structure, and the rate of foliar PM removal was established. Seven turfgrass species ( Liriope sp icata , Lolium perenne , Festuca elata , Poa pratensis , Zoysia sinica , Cynodon dactylon and Agrostis stolonifera ) were examined in simulated rainfall experiments with total rainfall amounts of 16 mm, rainfall intensities of 10, 15, and 20 mm·h –1 , and sampling intervals of 12, 8, and 6 min, respectively. The highest wash-off rates for foliar TSP, PM>10, PM2.5-10, and PM2.5 among the test plants were 84.05%, 87.99%, 78.62%, and 79.31%, respectively, with Liriope sp icata and Zoysia sinica exhibiting higher wash-off rates. Higher rainfall intensity led to greater wash-off rates, requiring less time to reach maximum wash-off rates. It is important to note that rainfall did not completely remove foliar PM, and PM retention after 20 mm· h –1 rainfall was lower than that after 10 mm· h –1 rainfall. Additionally, particulate wash-off rates decreased with the increase in groove width, leaf hair length, and leaf hair width in the leaf surface structure. The present study provides a scientific foundation for quantitative investigations into PM removal by garden plants and offers guidance for selecting urban greening plants.