Mechanical Crushing Research Articles

Extraction and Synthesis of Typical Carotenoids: Lycopene, β-Carotene, and Astaxanthin.

Carotenoids are tetraterpene compounds acting as precursors to vitamin A, with functions that include protecting eyesight, enhancing immunity, promoting cell growth and differentiation, and providing antioxidative benefits. Lycopene, β-carotene, and astaxanthin are particularly critical for health and have diverse applications in food, health products, and medicine. However, natural carotenoids are encased within cell structures, necessitating mechanical methods to disrupt the cell wall for their extraction and purification-a process often influenced by environmental conditions. Thus, improving the efficiency of carotenoid extraction from natural resources is of great interest. This review delves into the research progress made on the extraction processes, structures, and biological functions of carotenoids, focusing on lycopene, β-carotene, and astaxanthin. Traditional extraction methods primarily involve organic solvent-assisted mechanical crushing. With deeper research and technological advancements, more environmentally friendly solvents, advanced machinery, and suitable methods are being employed to enhance the extraction and purification of carotenoids. These improvements have significantly increased extraction efficiency, reduced preparation time, and lowered production costs, laying the groundwork for new carotenoid product developments.

Research on the Collection Characteristics of a Hydraulic Collector for Seafloor Massive Sulfides

Ore collection is very important in deep-sea mining for seafloor massive sulfide (SMS). In view of the characteristics of SMS ores produced by mechanical crushing, which contain coarse particles and a wide particle size distribution, in-depth research on the collection process with a device combining a rotary crushing head and a flat suction mouth was conducted. In this paper, solid–liquid two-phase flow in the hydraulic collection process with a drum rotation is carried out using the computational fluid dynamics-discrete element method (CFD-DEM), and the flow field characteristics and particle motion characteristics are analyzed. The results indicate that particles with a maximum diameter of 20 mm can be effectively collected when the suction velocity is 3 m/s. The collection process of SMS mainly goes through three stages: particle disturbance start-up, partial particle influx, and stable collection. In addition, the appropriate drum speed facilitates the collection of SMS ore. Finally, the correctness of the numerical method was assessed using similarity experiments. This work can be used to guide the design of underwater mining equipment.

Effect of curing conditions on cement based self-compacting mortar produced with mortar waste aggregate

Concrete and mortar wastes, which have a large volume and economic value among construction demolition wastes, are the most targeted demolition waste group to be recycled. An important area where construction demolition waste can be utilized is self-compacting mortar (SCM) systems. SCMs are innovative and economical systems designed to minimize the labor requirements that are difficult to meet in the production process. In this study, mortar waste aggregate (MWA) obtained by mechanical crushing and grinding was used in SCM elements by substituting different ratios (5-10-20-30-40 %) by mass to aggregate. In this way, it was aimed to evaluate both the sustainability of MWAs and the usability of MWAs in SCMs, which are considered as a new production technology. The fresh and hardened mortar tests performed in the study are presented comparatively. The physical (dry unit volume weight, porosity), durability (capillary water absorption) and mechanical properties (flexural tensile, compressive strength) of the hardened SCM elements are based on the determinations made at 3, 7 and 28 test days and according to different curing conditions (water curing, air curing and heat curing).In addition, X-ray Diffractometer (XRD) analysis was performed on specimens obtained from 0 %, 10 %, 20 % and 40 % MWA substituted specimens after heat curing (after 7 days water curing) and 28 days water curing. In the light of the data obtained, it is reported that SCM production with 10 % MWA substitution is feasible in terms of sustainability and engineering properties evaluated in this study.

A comparative study of mechanical crushing and pyrolysis techniques for separation and recovery of discarded polycrystalline silicon photovoltaic modules

With the rapid growth of the photovoltaic (PV) industry, efficient recovery and utilization of discarded polycrystalline silicon PV modules have attracted increasing attention. This study compares the application of mechanical crushing and pyrolysis techniques in the recovery of PV modules. The results indicate that while mechanical crushing can preliminarily disintegrate materials, its effectiveness in separating valuable materials such as silver and aluminum is limited, particularly for particles larger than 1 mm. In contrast, pyrolysis techniques demonstrate outstanding performance in removing organic matter and separating silicon wafers and glass, notably enhancing the recovery rate of large glass particles. However, the brittleness of silicon wafers presents a challenge during pyrolysis. Furthermore, the pyrolysis mechanisms of ethylene-vinyl acetate (EVA) film and backsheet materials are thoroughly discussed. The pyrolysis process of EVA film involves two stages: firstly, the preferential decomposition of acetyl oxygens on ester side chains, followed by further pyrolysis decomposition of the main chain and side chains to generate alkanes. Pyrolysis of polyethylene terephthalate (PET) begins with the generation of methyl and benzoyl radicals, while polyvinyl fluoride (PVF) and polyvinylidene fluoride (PVDF) pyrolysis initiates with the detachment of head-group units, followed by sequential detachment of chain units. Given the advantages of pyrolysis techniques, this study recommends them as the preferred method for PV module recovery.

Energy Efficiency Measurement of Mechanical Crushing Based on Non-Contact Identification Method

The efficiency of mechanical crushing is a key metric for evaluating machinery performance. However, traditional contact-based methods for measuring this efficiency are unable to provide real-time data monitoring and can potentially disrupt the production process. In this paper, we introduce a non-contact measurement technique for mechanical crushing efficiency based on deep learning algorithms. This technique utilizes close-range imaging equipment to capture images of crushed particles and employs deeply trained algorithmic programs rooted in symmetrical logical structures to extract statistical data on particle size. Additionally, we establish a relationship between particle size and crushing energy through experimental analysis, enabling the calculation of crushing efficiency data. Taking cement crushing equipment as an example, we apply this non-contact measurement technique to inspect cement particles of different sizes. Using deep learning algorithms, we automatically categorize and summarize the particle size ranges of cement particles. The results demonstrate that the crushing efficiencies of ore crushing particles, raw material crushing particles, and cement crushing particles can respectively reach 80.7%, 70.15%, and 80.27%, which exhibit a high degree of consistency with the rated value of the samples. The method proposed in this paper holds significant importance for energy efficiency monitoring in industries that require mechanical crushing.

Recyclable Technology of Thermosetting Resins for High Thermal Conductivity Materials Based on Physical Crushing

Epoxy resin, characterized by prominent mechanical and electric‐insulation properties, is the preferred material for packaging power electronic devices. Unfortunately, the efficient recycling and reuse of epoxy materials with thermally cross‐linked molecular structures has become a daunting challenge. Here, we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high‐performance material. Different particle size of waste epoxy micro‐spheres (100–600 μm) with core‐shell structure is obtained through simple mechanical crushing and boron nitride surface treatment. By using smattering epoxy monomer as an adhesive, an eco‐friendly composite material with a “brick‐wall structure” can be formed. The continuous boron nitride pathway with efficient thermal conductivity endows eco‐friendly composite materials with a preeminent thermal conductivity of 3.71 W m−1 K−1 at a low content of 8.5 vol% h‐BN, superior to pure epoxy resin (0.21 W m−1 K−1). The composite, after secondary recycling and reuse, still maintains a thermal conductivity of 2.12 W m−1 K−1 and has mechanical and insulation properties comparable to the new epoxy resin (energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm−1). This strategy expands the sustainable application prospects of thermosetting polymers, offering extremely high economic and environmental value.

Copper recovery from waste printed circuit boards using pyrite as the bioleaching substrate.

Waste printed circuit boards (WPCBs) can be bioleached for Cu recovery, but lack of substrate for the bioleaching culture. In this study, using pyrite as a bacterial substrate for bioleaching WPCBs and recovering Cu was explored. The results showed that the WPCBs bioleaching using pyrite as the bacterial substrate was feasible. Mechanical crushing was a suitable WPCBs pretreatment method. The optimal WPCBs and pyrite pulp densities were respectively found to be 1.25% (w/v) and 1.0% (w/v), and the suitable nitrogen source ratio ((NH4)2SO4: (NH4)2HPO4) was deemed as 2g/L: 2g/L, achieving a Cu2+ leaching efficiency of 95.60 ± 1.57% in 14 d. Copper in the bioleaching solution can be directly recovery via electrodeposition. The Cu recovery efficiency in 60min was up to 92.19 ± 1.35% under the optimal condition that the initial Cu2+ concentration and pH were respectively set at 7.34g/L and 2.75, and the current density was set at 200 A/m2. Copper was found as the dominant metal in the cathode deposits, existing in the form of Cu and Cu2O. This work provided a novel approach for bioleaching WPCBs and recovering Cu.

Qualitative Changes in Birch Sap after Freezing and Thawing

In this study, the qualitative changes in raw birch sap after freezing and thawing were determined. Ten-liter bottles and one-ton plastic containers with six replications were used for the freezing of birch sap and thawing of frozen sap. During and after the thawing, the physical and physical–chemical properties of the sap were measured. According to the results, as the ice melts, the concentration of acids and other soluble substances in the sap decreases, but changes in qualitative indicators indicate the beginning of fermentation processes through color changes and pH as the temperature of the melting sap becomes positive. As a result, to freeze raw sap in large-volume containers, it is necessary to develop fast thawing technology using auxiliary means—circulation, external energy sources, and mechanical ice crushing.

Deep blue emitting dual state fluorescent triphenylamine-dicyclohexylurea derivative: Multi-stimuli responsive fluorescence switching and methanol/water sensing

A new deep blue emissive organic fluorophore (N-cyclohexyl-N-(cyclohexylcarbamoyl)-4-(diphenylamino)benzamide (NCDPB)) was designed and synthesized, which showed strong fluorescence both in solution and solid-state. Solid-state structural analysis of NCDPB revealed non-planar twisted molecular conformation with extended hydrogen bonding between the amide functionalities. The propeller shaped triphenylamine (TPA) and non-planar cyclohexyl unit prevented close π…π stacking and produced strong deep blue emission in the solid state (λmax = 400 nm, quantum yield (Φf) = 12.6 %). NCDPB also exhibited strong solvent polarity dependent tunable emission in solution (λmax = 402–462 nm, Φf = 1.15 (compared to quinine sulphate)). NCDPB showed reversible fluorescence switching between two fluorescence states upon mechanical crushing and heating/solvent exposure. Mechanical crushing caused red shifting of fluorescence from 400 to 447 nm and heating/solvent exposure reversed the fluorescence. Further, NCDPB also displayed off–on reversible/self-reversible fluorescence switching upon exposure to trifluoracetic acid (TFA) and NH3. The repeated fluorescence switching cycles indicated high reversibility without any significant change of fluorescence intensity. The drastically different fluorescence of NCDPB in CH3OH and EtOH was utilized to distinguish them and monitor CH3OH contamination in ethanol and benzene. It showed limit of detection (LOD) of methanol up to 0.25 % and 7 % in benzene and ethanol, respectively. The water sensitive fluorescence modulation of NCDPB in organic solvents was used to sensing water contamination in common organic solvents. Thus, integration of twisted TPA with H-bonding urea produced dual state emitting organic fluorophore with multi-responsive fluorescence switching and solvent sensing.

Rapid dissolution without elemental fractionation by laser driven hydrothermal processing

Traditional dissolution of geologic samples often requires a significant time investment. Here, we present an alternative method for the dissolution of geologic materials using laser-driven hydrothermal processing (LDHP). LDHP uses laser energy directed onto a submerged sample, which increases the temperature and pressure at the liquid–sample interface and drives the hydrothermal dissolution coupled with photomechanical spallation, an ablative process. This uses focused 527 nm laser energy at 40 W average power, 1 kHz pulse repetition rate, and 115 ns pulse duration. When LDHP is performed on basalt geostandards (BCR-2 and BHVO-2) using the conditions outlined, we show that LDHP does not produce significant elemental fractionation and, thus, can be considered an alternative processing method to traditional mechanical crushing and acid digestion. Additionally, it is possible using LDHP to utilize the spatially confined beam to target and selectively isolate individual phases in a rock, potentially alleviating the need for mechanical separation of inclusions that are difficult to physically isolate. Furthermore, using this outlined method of LDHP, we demonstrate full dissolution of 120 mg of obsidian in 85 minu, meaning that LDHP is a potentially very useful method when sample processing is time sensitive.

Mechanochemical evolution of coal microscopic groups: A new pathway for mechanical forces acting on coal spontaneous combustion

Coal spontaneous combustion (CSC) remains a significant threat to regional ecological environments. As coal mining operations extend deeper into the earth, the increasingly complex mechanical force conditions in deep-seated mines escalate the potential risk of CSC. Mechanical forces such as ground stress and mechanical cutting are traditionally believed to be linked to CSC through the following pathway: mechanical forces act → mechanical energy is input → mechanical crushing and pulverization occur → coal–oxygen contact area increases → CSC accelerates. Noteworthily, these forces do more than just physically break coal; they also trigger a mechanochemical effect (MCE) that alters coal's microscopic chemistry. However, an independent evaluation of its influence on CSC was lacking. This study characterized coal's microscopic chemical group responses to the MCE. It was found that the MCE led to the degradation of aliphatic side chains while enhancing the polycondensation of aromatic ring structures, indicating a synergistic effect. Additionally, an increase in oxygen-containing functional groups, such as alkyl/aryl ethers, suggested enhanced interactions of the coal microscopic groups with oxygen due to mechanical forces. Based on these findings, an MCE-modified coal macromolecular model was developed and molecular quantum mechanical calculations were conducted. The results indicated that the MCE boosted coal macromolecule reactivity, thus facilitating easier activation. These conclusions were validated through modern thermal analysis tests. Finally, this study proposed a new pathway of mechanical forces acting on CSC: mechanical forces act → mechanical energy is input → the MCE occurs → evolutions of the microscopic groups within coal are induced → Activity of coal molecules is enhanced → CSC accelerates.

Mold Fungal Resistance of Loose-Fill Thermal Insulation Materials Based on Processed Wheat Straw, Corn Stalk and Reed.

The present study evaluates the mold fungal resistance of newly developed loose-fill thermal insulation materials made of wheat straw, corn stalk and water reed. Three distinct techniques for the processing of raw materials were used: mechanical crushing (Raw, ≤20 mm), thermo-mechanical pulping (TMP) with 4% NaOH and steam explosion pulping (SEP). An admixture of boric acid (8%) and tetraborate (7%) was applied to all processed substrates due to their anti-fungal properties. The fourth sample group was prepared from SEP substrates without added fungicide (SEP*) as control. Samples from all treatments were separately inoculated by five different fungal species and incubated in darkness for 28 days at 28 °C and RH > 90%. The highest resistance to the colonization of mold fungi was achieved by TMP and SEP processing, coupled with the addition of boric acid and tetraborate, where molds infested only around 35% to 40% of the inoculated sample area. The lowest mold fungi resistance was detected for the Raw and SEP* samples, each ~75%; they were affected by rich amount of accessible nutrients, suggesting that boric acid and tetraborate additives alone did not prevent mold fungal growth as effectively as in combination with TMP and SEP treatments. Together, the achieved fungal colonization scores after combined fungicide and pulping treatments are very promising for the application of tested renewable materials in the future development of thermal insulation products.

Influence of Ni Content on Microstructure and Hardness of Nickel-Graphite Abradable Seal Coatings Produced by Plasma Spraying

The influence of the initial shape of graphite powder and Ni content on the structure and properties of the nickel-graphite powders and plasma-sprayed coatings is investigated. The irregularly and spherically shaped graphite powders were produced by mechanical crushing and mechanical crushing with rolling, respectively. It is shown, that spherically shaped graphite powder has advantages in flowability and better deposition of Ni layer. The nickel-graphite core-shell powders with 50 and 75 wt.% Ni content were used to deposit coatings by plasma spraying. The composition, structure, and hardness of the nickel-graphite coatings were studied.

The treated recycled aggregates effects on workability, mechanical properties and microstructure of ultra-high performance concrete Co-reinforced with nano-silica and steel fibers

To promote the application of recycled aggregates (RA) in more high-performance engineering projects, it is necessary to scientifically modify and repair the RA, which is originally damaged by mechanical crushing and contains cracks and pores. This study investigates the influence of modified RA on the workability, mechanical properties, and microstructure of ultra-high-performance concrete (UHPC). Fresh state characteristic tests (slump and flowability), hardened mechanical property tests (compressive, axial tensile, elastic modulus, and four-point bending), and analysis of microstructure (SEM images and nuclear magnetic resonance (NMR) were performed on specimens with different modifications of RA. The results showed that after three different modifications (hydrochloric acid washing, cement slurry coating, and chemical strengthening) of RA, the apparent density increased and water absorption decreased. This resulted in improved workability and fluidity of the specimens containing modified RA, with increased compressive strength and elastic modulus by 15%, as well as enhanced bending performance indicators (flexural strength, toughness, and residual strength), while the axial tensile strength was not lower than that of specimens containing natural aggregates. Additionally, SEM analysis examined the pores between the cement matrix, interface transition zone (ITZ), and fibers, and how they were improved. The specimens with modified RA had a complete and continuous ITZ, with more thorough hydration reactions and better interface bonding. NMR analysis revealed a distinct "three-peak" structure in the T2 spectrum and showed the evolution of four types of pores in the microstructure, including an increase in the number of small pores and a decrease in the number of large and medium pores and microcracks. These research findings provide new insights into the application of modified RA and serve as a reference for the use of a suitable amount of modified RA in crack-resistant or other high-demand engineering projects.

Study on Deformation Behavior and Mechanical Properties of 42CrMo High-Strength Steel with Multi-Station Warm Upsetting

In order to find out the deformation behavior and mechanical properties of 42CrMo steel under warm upsetting conditions, the Gleeble-3500 thermal simulation testing machine was used to carry out a warm upsetting physical simulation experiment on 42CrMo steel. By controlling deformation temperature, strain rate, and constant temperature deformation pass, the microstructure evolution rule under different warm upsetting conditions was analyzed, and its hardness value was measured. Then, the simulation experiment is carried out based on the Deform-3D finite element platform. The results show that, with the increase in deformation temperature, 42CrMo steel has a temperature rise softening effect, which significantly reduces the peak value of rheological stress. At 650 °C, the maximum peak value of rheological stress is only 45.3% of that of cold upsetting deformation at room temperature, and the stress-strain curve tends to be gentle at the plastic deformation stage, which is the most suitable temperature for warm upsetting deformation. The maximum peak flow stress of 42CrMo steel increases with the increase in strain rate, but the number of deformation channels has little influence on the stress-strain curve. The warm, upsetting deformation can refine the internal grain structure significantly, and the grain refinement mechanism is mechanical crushing. When the temperature is slightly higher, the broken grain will recover, and the grain size will grow. During the process of warm upsetting, the strain rate has a great influence on the microhardness of the sample. The deformation pass has little influence on the hardness, and the hardness increases slightly with the increase in the deformation pass. Through the Deform-3D simulation, the correlation coefficient R and the average absolute relative error (AARE) between the simulation value and the experimental value were calculated, and the correlation coefficient R-value was 0.9948, and the average absolute relative error (AARE) was 2.05%, indicating that the simulation can accurately reflect the relationship between displacement and applied load.

Effects of Friction Stir Processing on the Microstructure and Mechanical Properties of an Ultralight Mg-Li Alloy

Magnesium–lithium alloys are arguably the lightest metal structural materials but have low strength. In order to increase strength, friction stir processing (FSP) is applied to a hot-rolled Mg-10Li-3Al-3Zn (LA103Z) sheet to study the effects on the microstructure and mechanical properties. In this study, the strengthening mechanisms of various FSP regions of an Mg-Li alloy were clarified by a combination of numerical simulation and experimental method. Based on ANSYS APDL, a finite element model with a moving heat source is established. Rotational speeds of 800, 1000, and 1200 rpm and traverse speeds of 100, 110, and 120 mm/min were used in this research. The simulation results confirm that the influence of the rotation speed on the alloy temperature field is greater than that of the travel speed. The temperature of the processing area increases with an increase in rotation speed and decreases with an increase in travel speed. Then, hot-rolled LA103Z alloy plates are processed by FSP. The correspondence between the numerical simulation and experiment was verified by infrared thermography. The results indicate that FSP decreases the grain size significantly for the dynamic recrystallization and dramatic mechanical crushing of the stirring pin. The α-Mg and AlLi are solid soluted in the β-Li matrix. The tensile strength of the processing zone is 260.67 MPa (1000 rpm, 110 mm/min) versus the 170.47 MPa of the base metal. The SZ has the highest microhardness of 77.8 HV (800 rpm, 120 mm/min) and decreases gradually to the BM. The severe deformation, recrystallization, and solid solution of the α-Mg are important factors contributing to the improved mechanical properties.

Fundamentals of the recycling of spent lithium-ion batteries.

This review discusses the critical role of fundamentals of battery recycling in addressing the challenges posed by the increasing number of spent lithium-ion batteries (LIBs) due to the widespread use of electric vehicles and portable electronics, by providing the theoretical basis and technical support for recycling spent LIBs, including battery classification, ultrasonic flaw detection, pretreatment (e.g., discharging, mechanical crushing, and physical separation), electrolyte recovery, direct regeneration, and theoretical calculations and simulations. Physical chemistry principles are essential for achieving effective separation of different components through methods like screening, magnetic separation, and flotation. Electrolyte recovery involves separation and purification of electrolytes through advanced physical and chemical techniques. Direct regeneration technology restores the structure of electrode materials at the microscopic scale, requiring precise control of the physical state and crystal structure of the material. Physical processes such as phase changes, solubility, and diffusion are fundamental to techniques like solid-state sintering, eutectic-salt treatment, and hydrothermal methods. Theoretical calculations and simulations help predict the behaviour of materials during recycling, guiding process optimization. This review provides insights into understanding and improving the recycling process, emphasizing the central role of physical chemistry principles in addressing environmental and energy issues. It is valuable for promoting innovation in spent LIB recycling processes and is expected to stimulate interest among researchers and manufacturers.

Elimination of surface defects in luminescent crystals through solid-liquid interface friction.

In this work, we report a simple yet robust strategy for eliminating surface defects in red-emitting fluorides through solid-liquid interface friction under elevated temperature and high pressure. This method is minimally dependent on the solvent type and especially excels at stripping away the abundant surface defects caused by mechanical crushing.

Novel Crushing Technique for Measuring δ18O and δ2H Values of Fluid Inclusions (H2O) in Quartz Mineral Veins Using Cavity Ring‐Down Spectroscopy

Fluid inclusions in mineralized fracture infillings (i.e., veins) could preserve information about subsurface fluids like temperature and salinity. The isotopic composition of water in these fluid inclusions could provide direct evidence of the provenance of these mineral‐forming fluids. So far, the isotope compositions of fluid inclusions have been mainly derived from carbonate veins and other precipitates, like speleothems. The aim of this study is to analyse the δ18O and δ2H isotopic compositions of aqueous fluid inclusions of quartz veins using a cavity ring‐down spectroscopy (CRDS) analyser in combination with a moisturized nitrogen background and mechanical crusher. For this study, we analysed δ18O and δ2H values of fluid inclusions in quartz veins from three north‐western European locations formed during the Variscan orogeny. Prior to crushing, the fluid‐rich quartz fraction was separated from the pure quartz fraction, from other mineral phases and host rock by using conventional heavy liquids and magnet separation. Raman spectrometry detected some rare occurrences of hydrocarbon, methane, and nitrogen in the fluid inclusions. The samples were sequentially crushed to elucidate the potential impact of different fluid inclusion assemblages (FIA) on the δ18O and δ2H values. The results from single and sequential mechanical crushing, together with interlaboratory comparisons, exhibit reliable and consistent isotopic patterns across locations with high precision (for δ18O: 1σ SD < 0.8‰; for δ2H: 1σ SD < 1.5‰). The obtained data occur in three different clusters for three study zones, providing evidence for the presence of meteoric‐derived fluids in the fold‐and‐thrust belts of the Variscan orogeny. These findings demonstrate that the CRDS approach can be successfully applied to quartz minerals, investigating fluid pathways within the upper crust and the formation of these secondary minerals.

Preparation of ultrafine PVP-BiO2-x by mechanochemistry modification for enhanced photocatalytic activity

This study reports the preparation of ultrafine PVP-BiO2-x nanomaterials through ball milling modification, with a particle size distribution range of 5–10 nm. During ball milling, PVP played a protective role in BiO2-x oxygen-deficient materials, reducing the oxidation rate of BiO2-x during mechanical crushing and allowing BiO2-x to exhibit good dispersibility in water. The ultra-small particle size of PVP-BiO2-x enhances its absorption capacity in the visible light spectrum, thereby improving its performance in photocurrent testing. Compared with bulk BiO2-x, PVP-BiO2-x exhibits enhanced photocatalytic performence for rhodamine B and methyl orange under visible light irradiation. This study successfully prepared ultra-small spherical PVP-BiO2-x, showcasing its photocatalytic principles and providing valuable insights into mitigating oxidation challenges in the large-scale fabrication of BiO2-x nanomaterials.