Soil salinization is a major cause of structural degradation, strength deterioration, and deformation intensification in earthen heritage sites across northwestern China. Therefore, investigating salt-induced damage mechanisms in such soils holds significant engineering and conservation value . In this study, uniaxial compression tests were performed on soil samples with varying sodium sulfate (Na₂SO₄) contents (0

Freeze-thaw rock damage evolution is crucial for safety assessment and disaster early warning in cold region engineering. This study implements acoustic-thermal monitoring to identify precursors of geotechnical instability. By correlating acoustic emission (AE) parameters (energy, amplitude) with infrared thermography indices (maximum/mean radiation temperature), we dynamically characterize localized damage progression from initiation through shear band formation to ultimate failure. The self-correlation coefficient and coefficient of variation are proposed to quantitatively describe the loading failure process and localization of freeze-thaw sandstone. The spatial failure characteristics of localization are analyzed, and the damage time characteristics are revealed. The research findings demonstrate that AE event nucleation clusters emerge at 0.8 sigma(c)similar to sigma(c), signaling localized deformation initiation. The deformation localization zone of freeze-thaw rock is first formed in the middle, and the initial damage location significantly affects the formation and failure mode of the localization zone. The self-correlation coefficient and the mutation point of the coefficient of variation of the acoustic emission can be used as the criterion of its formation time, and the change rule of the time and space entropy curve reflects the localization stage. The localized failure time of sandstone is advanced with the increase of freeze-thaw times. Comparative analysis of acoustic-thermal indicators reveals that auto-correlation coefficients exhibit superior sensitivity in characterizing deformation localization compared to thermal parameters. The integration of infrared thermography and AE monitoring significantly enhances reliability in identifying precursory signals for rock instability and engineering catastrophes in cold regions.The combination of acoustic emission and thermal imaging technology can realize the advance warning of rock burst in the early warning of tunnel freeze-thaw disaster. In the stability management of frozen soil slope, a three-level risk classification threshold can be constructed to provide theoretical support for the differential support decision of engineering in cold regions. It is more advantageous to improve the reliability of freeze-thaw rock instability and failure and rock engineering disaster precursor identification in cold regions.

Repeated mining of shallow-buried close-distance coal seams can disturb the fractured strata remaining in the goaf of the upper coal seam. Under gully terrain, mining disturbance is coupled with surface-relief effects, which may reactivate the overburden structure and induce dynamic strata-pressure behavior. In particular, when the working face advances across gullies, the change in surface slope alters the spatial distribution of roof load, while lower-seam extraction further disturbs the fractured rock mass formed by upper-seam mining, increasing the risk of severe strata-pressure behavior and support-crushing accidents. Taking the cross-ditch mining of the 2−2 and 3−1 coal seams in Anshan Coal Mine as the research object, this study integrates field geological investigation, theoretical calculation, physical similarity simulation, and field engineering verification to analyze overburden structural evolution, key-stratum breaking characteristics, and support-load variation under gully terrain. The results show that gully landforms generate obvious nonuniform loading above the working face. During upslope advance, the roof load gradually increases from the goaf side to the solid-coal side, causing tensile stress concentration at the fixed end of the key stratum and accelerating rock-stratum failure. A cantilever rock-beam mechanical model subjected to parabolic nonuniform loading was established, and the maximum breaking interval of the key stratum was calculated as 24.09 m. With increasing gully slope angle, the load gradient intensifies, the rock-beam breaking interval decreases, and the risk of overburden instability increases. Physical similarity simulation indicates that, when the 2−2 coal seam working face passes through the 45° steep-slope section, the fractured overburden is more likely to form a stepped rock-beam structure, accompanied by slope rotation, stepped surface subsidence, and a sharp increase in support pressure. Under the 30° gentle-slope condition, The lateral confinement effect is stronger, roof movement is more gradual, and support-pressure fluctuation is reduced. During subsequent extraction of the lower 3−1 coal seam, repeated mining disturbance reactivates the overlying goaf structure, and the upper stepped rock beam and lower hinged rock beam couple to form a double composite structure. When the fracture lines of the upper and lower key strata are staggered, the instability load of the upper structure is mainly buffered by caved gangue and interburden strata. The calculated support resistance in the asynchronous breaking stage is 8248.04 kN, which agrees well with the field-measured value of 8273 kN. When the fracture lines tend to coincide and synchronous breaking occurs, the unstable load of the upper key block is transferred downward and superimposed on the structural load of the lower key block, increasing the required support resistance to 15,165.55 kN, far exceeding the rated working resistance of the ZY9200/15/29 hydraulic support. Sensitivity analysis indicates that gully slope angle is the dominant factor affecting support resistance. As the slope angle increases from 30° to 60°, the support resistance increases from 13,228.65 kN to 18,278.43 kN, and the normalized support-resistance index increases from 0.872 to 1.205. Therefore, synchronous breaking of double key strata is the main mechanical cause of sudden support-load increase and support-crushing risk during cross-ditch mining of shallow-buried close-distance coal seams. The results can provide a basis for hydraulic support selection, roof weakening, weighting-interval control, and dynamic strata-pressure prevention under similar conditions.

To overcome the limitations of conventional passive insulation in cold-region tunnel frost prevention, an active temperature-control method that exploits surrounding rock-lining synergy with phase-change energy storage is proposed. This study establishes a multiscale phase-field model to derive the governing equations for the solid-liquid phase change and determine the optimal phase-change temperature.In the context of the Kangding No. 2 Tunnel, a composite phase change material (PCM) made of decanoic acid and decanol was developed. Its structural, thermophysical, and durability properties were systematically evaluated under cyclic freeze-thaw conditions. Numerical simulations were employed to analyze the thermal response and latent heat regulation mechanisms, focusing on varying mix ratios, plate thicknesses, and cycling regimes.The results demonstrate that the composite PCMs exhibit high latent heat storage capacity compared to other low-temperature candidates. When applied in a surrounding rock-lining synergy system, the material's solid-liquid phase transition effectively shaves thermal peaks and fills valleys, creating a thermal buffer layer. This transforms the insulation strategy from one of passive isolation to active regulation.The study further reveals that insulation board thickness is positively correlated with thermal efficiency, but the efficiency gains diminish with increasing thickness. Excessive thickness introduces a thermal inertia zone due to latent heat release lag, resulting in reduced PCMs utilization. Additionally, while temperature control efficiency showed a slight decline after multiple freeze-thaw cycles, the overall durability of the composite PCMs was minimally affected by cyclic conditions. These findings offer significant theoretical and practical value for freeze protection and thermal insulation design in cold-region tunnel engineering.

Observing and quantifying the discontinuous structural evolution of rocks under thermo-mechanical loading remains a key challenge in cold region rock mechanics. CT real-time scanning of freeze-thaw sandstone under coupled loading captured 3D digital images of damage structures during uniaxial compression. A local 3D digital volume correlation (DVC) method with the Inverse Compositional Gauss-Newton (IC-GN) algorithm enabled non-contact measurement of internal deformations during compression failure. Full-field 3D strain distributions and damage characteristics were quantified under thermo-mechanical conditions. The method quantitatively visualized internal damage deformation, showing that the sandstone's meso-structure provides an effective DVC carrier. IC-GN-based analysis revealed that macro-damage propagates along pre-existing meso-damage paths under compressive loading, with initial damage structures dictating crack propagation directions and spatial distribution patterns at failure. As loading intensifies, localized deformation zones progressively coalesced with failure regions, while strain field distribution correlates consistently with crack morphology during sandstones rupture. The peak porosity of rock specimens at failure progressively rises under repeated freeze-thaw cycles. This research advances transparent analysis of discontinuous structures and multi-physical field effects, offering insights for frost damage mitigation in cold region engineering.

Cyclic freeze-thaw actions progressively degrade sandstone's mechanical integrity and alter its fracture behavior, significantly impacting safety and stability assessments of engineering structures in cold regions. This study conducted uniaxial compression tests on rocks subjected to varying numbers of freeze-thaw cycles, generating complete stress-strain curves that characterize the entire failure process of freeze-thaw sandstone. Thermodynamic principles were applied to analyze energy evolution (total, elastic, and dissipated energy) during uniaxial compression failure, elucidating the intrinsic physical relationship between energy dissipation and mechanical deterioration, as well as energy release and specimen failure. This study proposes a plasticity index to quantitatively characterize the impact of freeze-thaw cycles on rock failure modes. Integrating damage mechanics and energy dissipation principles, we establish a damage evolution equation for freeze-thaw sandstone under compression that incorporates the plasticity index. Furthermore, a damage constitutive model is developed, characterizing the brittle-to-plastic transition in failure modes of freeze-thaw sandstone. The results demonstrate that pre-peak irreversible energy loss and post-peak fracture energy exhibit a positive correlation with the number of freeze-thaw cycles, serving as key determinants for plastic (brittle) failure modes in sandstone. During the failure of freeze-thaw cycled rocks, energy dissipation induces meso-structural damage, while the release of internally stored elastic energy acts as the primary driving force for macroscopic failure. The proposed plasticity evaluation index quantitatively characterizes the transition from brittle to plastic failure in rocks subjected to freeze-thaw cycles. A constitutive model for freeze-thaw sandstone, developed based on this index, elucidates the mechanism by which freeze-thaw processes influence rock failure modes. These findings establish a scientific foundation for the quantitative assessment of failure behavior in freeze-thaw-affected rocks.

Multi-well interference in unconventional reservoirs lacks clear mechanistic understanding, especially for scenarios requiring high-resolution pressure transient simulations. We developed a numerical transient flow model to study interference responses in multi-well pads with different fracture hits. The model features a high-resolution unstructured grid node-constraining algorithm that honors complex geometries near fractures and wellbores, with appropriate transmissibility and well-index corrections to accurately capture second-level interference responses. dp/dt analysis with conventional dp/dln(t) was integrated to better identify transient flow regimes in high-conductivity media. Our approach reveals seven distinct transient flow regimes and four characteristic fluctuations caused by wellbore storage effects, fracture hits, pressure-front communication, and rate changes, respectively. Sensitivity analysis shows minimal detectable interference in matrix-connected wells in low-permeability reservoirs, while identifying diagnostic discontinuous jumps in dp/dt curves during production ratio changes. Our field case study of a four-well pad demonstrates how fracture joint characteristics affect pressure distribution and flow velocity, providing valuable diagnostic insights for optimizing multi-well pad development.

The contradiction between the growing accumulation of electronic waste and the urgent demand for high-performance electronics has promoted the development of new eco-friendly and multifunctional electronic devices, but their ability to resist inductive interference in harsh environments still faces challenges. This paper innovatively combines papermaking technology with environmental protection concepts, proposing a high-performance composite nanofiber paper (MFP) that is suitable for wearable motion sensing and triboelectric energy harvesting in all-weather conditions. By regenerating cellulose microfibers from agricultural waste loofah and incorporating functional montmorillonite (MMT), carbon nanotubes (CNTs), and methyltrichlorosilane (MTS), the obtained MFP exhibits exceptional waterproofing (WCA = 152 degrees), self-cleaning, heat resistance, and flame retardancy, ensuring long-term electrical performance stability both underwater and under 1 kW/m2 solar radiation. The MFP-based strain sensor not only features high sensitivity (13.75 kPa-1), rapid response (80 ms), and exceptional durability (over 10,000 cycles) but also achieves latitude and longitude positioning, significantly enhancing information transmission efficiency and emergency rescue capabilities. The integrated smart insole enables reliable biomechanical analysis of gait, posture, and foot abnormalities. Importantly, MFP can also be extended to the TENG, providing a peak power density of up to 2.7 W/m2, offering a green solution for outdoor emergency energy supply.

The isolated working face is significantly impacted by the adjacent goaf and the mining activities of the working face itself, causing the overlying rock layers above the working face to exhibit far more intense activity compared to an ordinary working face. The stress levels are high, and the surrounding rock suffers severe damage, posing serious challenges to the safe and efficient extraction of the working face. Improving the service life of the retreating roadway in an isolated working face is a pressing technical issue that coal mining companies must address. Focusing on the characteristics of the strata and mining conditions of the 8213 isolated working face in the Yanjiahe Coal Mine, which features a three-soft coal seam, a combination of field investigation, theoretical analysis, on-site monitoring, and numerical simulation methods was employed. This approach aimed to analyze the fundamental laws of mine pressure behavior in the three-soft coal seam isolated working face as well as the deformation and failure mechanisms of the surrounding rock in the retreating roadway. Using elastic thin plate theory, it was determined that the basic roof periodic fracture step of the 8213 isolated face in the Yanjiahe Coal Mine is approximately 23 m. Field mine pressure monitoring on the 8213 isolated working face revealed that during non-periodic pressure events, the support resistance of the working face generally fluctuated stably below the rated working resistance. When the basic roof collapsed, the average working resistance of the support showed a significant increase with periodic pressure steps ranging from 16 to 27 m and an average of 22 m. Numerical simulations were further used to analyze the changes in stress and the plastic zone of the overlying rock on the 8213 isolated working face, clarifying the mechanism by which instability in the overlying rock structure leads to incidents. This analysis provides theoretical support for the safe mining of isolated working faces.

In rock slopes with a three-section landslide, the locking section is the key control factor. This study conducted double-sided freeze–thaw tests on a scale model of a rock slope with a three-section landslide in a cold region. We monitored the changes in frost heave force, strain, and fracture during the water–ice phase change and investigated the effect of the trailing edge tensile crack length on the frost heave fracture of the locking section. A crack frost heave model was proposed based on rock and fracture mechanics to explore the mechanism of slope crack freeze–thaw weathering. According to the results, the slope shoulder froze first, with the freezing front progressing from the slope shoulder to the interior of the rock mass. The fracture failure in the three-section rock slopes was mostly caused by the frost heave of the trailing-edge tensile cracks. The largest frost heave force and locking section deformation occurred when the temperature of the top of the trailing edge tensile crack decreased from −3.5 °C to −6 °C (whereas that of the bottom of the crack dropped from 0 °C to −2.6 °C). Additionally, the results demonstrate that the frost heave force is positively correlated with the length of the trailing edge tension crack, and shear marks are virtually absent on the tensile fracture surface.

Soil salinization is an important factor affecting the durability deterioration of infrastructure structures in northwest China. The salt migration and crystallization caused by soil salinization have a significant impact on the thermo-electrophysical properties of soil. In this paper, the resistivity test and thermal conductivity test of soil with different moisture content and different Na2SO4 content were carried out to explore the response law of different moisture and salt content to the thermoelectric physical properties of soil. The test results show that the resistivity decreases with the increase of Na2SO4 content under the premise of moisture in the soil, and the change is the most obvious from 0 to 2

Given the potential for dynamic load-induced support crushing that may occur during mining under an interval goaf through an isolated coal pillar (ICP) in shallow closely spaced coal seams, this paper systematically explored this issue through a case study of the 30,103 working face at the Nanliang Coal Mine. We employed a combined approach of similarity simulations, theoretical analyses, numerical simulations, and field measurements to investigate the catastrophic failure mechanisms and prevention strategies for dynamic pressure-related hazards encountered when mining a lower coal seam that passes through an ICP. The findings indicated that the synchronous cutting instability of the interlayer effective bearing stratum (IEBS) and double-arch bridge structure of the ICP roof were the primary causes of dynamic load-induced support crushing at the working face. A mechanical model was developed to characterize the IEBS instability during mining under an interval goaf. The sources and transmission pathways of dynamic mining pressure during mining passing through the ICP were clarified. The linked instability of the double-arch bridge structure of the ICP roof was induced by IEBS failure. The UDEC numerical model was utilized to elucidate the instability of the IEBS during mining in the lower coal seam and to analyze the vertical stress distribution patterns in the floor rock strata of the interval goaf. A comprehensive prevention and control strategy for roof dynamic pressure, which includes pre-releasing concentrated stress in the ICP, strengthening the support strength of the working face, and accelerating the advancement speed was proposed. The effectiveness of this prevention and control strategy was validated through actually monitoring the characteristics of mining pressure data from the 30,103 working face following pressure relief. The findings provide valuable insights for rock stratum control of shallow and closely spaced coal seam mining under similar conditions.

The frequent water pollution problems have caused serious harm to the ecological environment and human health, among which, a large number of waste water contains heavy metal ions, organic dyes, oil-water emulsion and other pollutants. Therefore, it is particularly important to prepare multifunctional materials that can separate these pollutants and purify wastewater. In this paper, ovalbumin (OVA), phytic acid (PA) and egg shell powder (ESP) and TiO2 particles were used to construct a composite system, which was loaded on fabric, cotton and PVDF membrane by impregnation method. The preparation of OVA-ESP-TiO2-PA modified materials which can efficiently separate various oil-water mixtures and oil-water emulsions were successfully achieved. The modified material could achieve high flux (up to13458 L m(-2)h(-1)) and separation efficiency (> 99 %) for various mixtures of oil and water by gravity-driven. Typically, it shows good stability and durability under strong acid and alkali (pH=1-12) and different temperatures (T = 10-60 degree celsius), and can be reused. What's more, the modified materials can effectively adsorb organic dyes (> 92 %) and heavy metal ions (up to 85 %) and can degrade organic dyes by ultraviolet light. It provides a new idea for the separation of oil-water mixture and the purification of waste liquid containing organic dyes and heavy metal ions, which has a good application prospect in the treatment of industrial wastewater and domestic wastewater.

In coal seam groups where the spacing between the upper and lower seams is small, the lower seam working face is significantly influenced by residual coal pillars from the upper seam and the void spaces created during mining. This presents considerable challenges for underground mining safety. Through field investigations, the layout of the coal seam quarry above the working face of the 3−1 coal seam in Yanghuopan Mine was examined, along with the distribution of the residual coal pillars. This allowed for the identification of the interlayer rock strata characteristics. Subsequently, we analyzed the mechanism of directional hydraulic fracturing and decompression to determine the key parameters of the 3−1 coal seam. Using the Rock Fracture Process Analysis 3D (RFPA 3D) numerical simulation, we evaluated the effects of various factors on the initiation and propagation of hydraulic fracturing-induced cracks, formulated the evolution law of these fractures, and incorporated the damage variables into the analysis. Additionally, we assessed the influence of different parameters on crack initiation and extension during hydraulic fracturing, using RFPA 3D simulations to derive the evolution law governing directional hydraulic fractures. This allowed us to define the hydraulic fracturing parameters for the 3−1 interbedded rock layers by integrating the process parameter calculations with the damage variables. Based on these findings, an on-site implementation plan was developed and executed, followed by a comprehensive evaluation of the construction results. The study concludes that directional hydraulic fracturing and decompression effectively contribute to the prevention and control of roof-related disasters in the mining of lower coal seams where seam spacing is minimal. This research offers valuable theoretical insights and practical reference for disaster prevention and control in similar geological conditions.

To address coal pillar instability, the study focuses on the 3-1 coal seam coal pillar at Nanliang Coal Mine. It analyzes the bending deformation energy of the main roof and the pre-yield elastic energy of the coal pillar's elastic zone through theoretical analysis, similar simulation, and field measurements. The formula for the bending elastic energy of the main roof is derived by establishing the mechanical model of the roadway's main roof near the goaf side. Based on the side abutment stress distribution of the coal pillar, the calculation of the pre-yield elastic energy distribution along the width direction of the coal pillar's elastic zone is conducted, leading to the derivation of the instability energy criterion for the coal pillar. The range analysis method is used to analyze the influencing factors and distribution patterns of the bending elastic energy of the main roof and the pre-yield elastic energy of the coal pillar's elastic zone. Findings indicate that the main roof's tensile strength is the primary factor influencing bending elastic energy. Higher tensile strength of the main roof, and smaller load, larger thickness and elastic modulus on the overlying strata, lead to higher bending elastic energy in the main roof. The internal friction angle, width of the coal pillar, and elastic modulus of the coal seam notably impact the pre-yield elastic energy of the coal pillar's elastic zone. A larger internal friction angle and coal pillar width, along with a smaller elastic modulus, result in higher pre-yield elastic energy in the coal pillar's elastic zone. Using the working face of 3-1 coal seam in Nanliang Coal Mine as the engineering context, the study calculates the minimum coal pillar width required for stability. Physical simulations and field monitoring demonstrate that with a 9 m-wide coal pillar, there is no apparent deformation or failure in the surrounding rock of the roadway, indicating good internal rock stability.

The mining of shallow coal seam groups triggers the activation of overlying strata, leading to increased pressure and support difficulties, thereby posing a threat to the safe extraction of underlying coal seams. Against the backdrop of Longhua Coal Mine, this study utilized physical similarity simulation experiments to obtain the activated, restructured load-bearing structure and the migration characteristics of overlying strata. Theoretical calculations were employed to establish both a rolling friction mechanics model for the activated load-bearing structure and a mechanical model for the combined load-bearing structure of key strata. The research indicates that during the initial activation phase, the load-bearing structure exhibits a V-shaped hinged arch, with directly collapsed rock masses transitioning towards spherical shapes, resulting in the sub-key strata shifting from sliding friction to rolling friction. Based on the rolling friction mechanics model of the activated load-bearing structure, we derived the rolling friction coefficient of key blocks in the sub-key strata and the instability criterion of the load-bearing structure under rolling friction conditions. Considering the migration characteristics of the activated restructured load-bearing structure, four types of combined load-bearing structures were identified, and the load calculation formulas in the mechanical model were derived, with the rationality of these formulas verified through case analysis.

In the development of mineral resources and engineering construction in the western region, sandstone is one of the main engineering geological aquifers, and the freezing and thawing environment affects the mechanical and deformation characteristics of sandstone. In order to study the deterioration and damage characteristics of mechanical properties of loaded rocks under the influence of freeze-thaw environment, red fine sandstone in Shaanxi province was taken as the research object, and freeze-thaw cycle tests and uniaxial compression tests were carried out for 0, 5, 10, 20 and 30 times, and the stress-strain curve and mechanical characteristic parameters of the whole uniaxial compression process of frozen-thawed sandstone were obtained. The mechanical characteristic parameters of frozen-thawed rocks were analyzed, and the deterioration model of rock mechanical properties under freeze-thaw environment was established. Based on the influence of freeze-thaw environment on rock damage, considering the characteristics of rock compaction stage in deformation stage, a modified statistical damage constitutive model considering compaction stage is established. The results show that with the increase of freeze-thaw cycles, the proportion of rock compaction stage is increasing, and the peak value should also increase gradually. Brittle failure occurs in the first 30 freeze-thaw cycles, and the brittleness of rock is obviously weakened after 30 freeze-thaw cycles, and the strain softening stage is obvious. The loss rate of mechanical characteristic parameters increased rapidly in the first 10 times of freeze-thaw cycle, and then slowed down obviously. After 30 freeze-thaw cycles, the peak strength loss rate is 47.27% and the elastic modulus loss rate is 60.35%. Among them, the loss rate of mechanical characteristic parameters increases linearly with the number of freeze-thaw cycles, and the mechanical properties of rocks decrease exponentially after freeze-thaw. The peak strength and elastic modulus of rocks under freeze-thaw environment can be accurately predicted by using the pore characteristics of rocks under freeze-thaw environment. The modified statistical damage constitutive model considering the compaction stage has a higher fitting degree with the test curve, and the modified theoretical model can provide reference for the deterioration of mechanical properties and damage prediction of frozen-thawed rocks.

The surrounding rock of tunnel engineering in an alpine mountainous environment is prone to frequent freeze–thaw action due to fissure water and temperature differential, which leads to crack propagation and even failure in rock. Freezing sandstone CT damage-free scanning studies were conducted. Based on deep learning theory, the U-Net network technique is utilized to naturally merge high-resolution properties of frozen rock CT images in the shrinking path with low-resolution characteristics in the expansion path. Intelligent detection of freezing rock fissures and geometric information parameters at the pixel level has been accomplished. The primary fracture structure and its parameters of the sandstone with natural damage during the freeze–thaw process are obtained, and the pixel-level intelligent identification of the meso-structure and geometric information parameters of the freeze–thaw rock fracture is realized. This justifies the classification of naturally cracked rock under load and freeze–thaw as a discrete time-dimensional evolution system. The dynamic process and mechanical characteristics of meso-damage propagation of naturally fractured rock under freeze–thaw and compression load are investigated using Casrock numerical computation software, which is based on the cellular automata theory. The results reveal that when the number of freeze–thaw cycles rises, the random rate of fracture network structure distribution increases, the uniformity of fracture distribution increases, and the dominating direction decreases. The sandstone's secondary fractures progressively increase as the fracture dominant angle rises, and the rock sample's failure mode eventually shifts from tensile failure to compression-shear mixed failure. When the comprehensive dominant angle of fracture is 60°, the fracture of freeze–thaw rock is more prone to expansion and its mechanical strength deteriorates more. The fractured rock creates narrow strip directional damage along the end of the original fracture when subjected to compressive load, exhibiting typical localization features. The main crack and the secondary crack dominate the crack progression. The number of secondary fractures inside sandstone steadily grows as the fracture's comprehensive dominant angle increases. The direction of the crack penetration development is determined by the comprehensive dominating angle of the fracture.

Low power density and poor wear resistance seriously hinder the application of a triboelectric nanogenerator (TENG) in daily environments. However, current research has mainly focused on improving the performance of TENGs through inorganic fillers while neglecting the important property of wear resistance. Due to the excellent properties of stearic acid (SA), such as its cheap and easy availability, high electronegativity, wear resistance, hydrophobicity, and lubricity, as well as promoting the formation of electroactive beta phase polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), SA can be used as an organic multifunctional filler to improve the electrical output performance and wear resistance of TENG while increasing its hydrophobicity. In this work, we doped SA into polytetrafluoroethylene (PTFE)/PVDF-HFP matrix by solution casting method and template method to form SA-doped PTFE/PVDF-HFP(SA-PTFE/PVDF-HFP) composite polymer film, which were assembled with silk to form SA-TENG. Most importantly, the addition of 3 wt % SA not only increases the voltage and current of TENG by 3.7 times and 3.6 times, respectively, but also reduces the coefficient of friction and the amount of wear of TENG by 40.8 and 87.5%, respectively, and increases the hydrophobic angle by 12 to 133(degrees), which ensures the long-term and stable operation of TENG in different environments. In addition, SA-TENG can not only harvest energy from the surrounding environment and charge portable electronic devices but can also be used as a self-powered sensor to monitor human movement. This study not only provides a feasible strategy for organic fillers to solve the bottleneck problem of TENG application but also broadens the application scenarios of TENG.

As energy scarcity and environmental pollution become increasingly problematic, developing non-polluting and sustainable hydrogen production technologies is crucial, with an emphasis on developing high-efficiency and easily available electrolytic hydrocatalysts. Herein, we present a novel, economical self-supporting electrode, W-MoS2/FeNi2S4/NF, fabricated by a simple hydrothermal method. Benefiting from the insitu growth of uniformly dispersed micro-and nanoparticles with an ultrathin nanosheet-like shape on the surface and heterogeneous engineering and heteroatom doping, the catalytic electrodes possess surface superhydrophilic/underwater superaerophobic properties and superb intrinsic catalytic activity. The superhydrophilic/underwater superaerophobic properties of the catalytic electrodes allow for rapid infiltration of the electrolyte solution into the electrode and accelerate mass transfer while also allowing for the desorption of bubbles from the electrode surface and avoiding the bubble shielding effect, resulting in a significantly increased electrocatalytic rate. With current densities as high as 10 mA cm(-2) for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, W-MoS2/FeNi2S4/NF displayed lower overpotentials of 92 and 177 mV. More impressively, only a low cell voltage of merely 1.5 V is sufficient to achieve a current density of 10 mA cm(-2), achieve overall water splitting in an alkaline electrolyte, and exhibit up to 20 h electrochemical durability. Above all, it has been demonstrated that surplus electricity from intermittent energy sources may be used to create eco-friendly hydrogen energy by electrolyzing water, preventing resource waste. This work provides novel insights into the preparation of inexpensive, high-efficiency bifunctional electrocatalysts and new directions for intermittent energy generation for hydrogen production.