High Chemical Inertness Research Articles

Current State-of-the-Art and Perspectives in the Design and Application of Vitrimeric Systems

To fulfill the current circular economy concept, the academic and industrial communities are devoting significant efforts to plastic materials’ end-of-life. Unlike thermoplastics, which are easy to recover and re-valorize, recycling thermosets is still difficult and challenging. Conversely, because of their network structure, thermosetting polymer systems exhibit peculiar features that make these materials preferable for several applications where high mechanical properties, chemical inertness, and thermal stability, among others, are demanded. In this view, vitrimers have quite recently attracted the attention of the scientific community, as they can form dynamic covalent adaptive networks that provide the properties typical of thermosets while keeping the possibility of being processed (and, therefore, mechanically recycled) beyond a certain temperature. This review aims to provide an overview of vitrimers, elucidating their most recent advances and applications and posing some perspectives for the forthcoming years.

Tuning Selectivity of Two-Dimensional Based Gas Sensors Via Monolayer Hexagonal Boron Nitride Encapsulation

Hexagonal boron nitride (h-BN) serves as an excellent encapsulation material in two-dimensional (2D) materials owing to its insulating nature, high thermal stability, chemical inertness, and impermeability. The surface of h-BN without dangling bonds enables effective shielding of surface charge traps and dangling bond effects on the substrate. Moreover, the defects in h-BN can serve as mediators for charge transfer. In this study, monolayer h-BN grown by CVD is utilized to encapsulate 2D semiconductor gas sensors. We demonstrate that the encapsulated gas sensors exhibit superior stability, and most importantly, significant enhancements in gas selectivity, especially for NO2 and NO, addressing a longstanding issue in gas sensing technology. Figure 1

Study of Partial Silica Coating and Heat Treatment of PCNF to Improve Durability of Low-Temperature Fuel Cells

In fuel cells, platinum is typically applied to the supporting carbon to improve performance and reduce platinum usage. Typically, Pt/C is used as a cathode catalyst for ORR. However, for practical use, the durability of Pt/C needs to be improved. The carrier material for catalysts used in fuel cells is carbon. There is a basic requirement to improve the carbon carrier near the high surface area, so that deposition of small platinum particles, improved stability under the operating conditions of the fuel cell, and high conductivity are realized. CNFs have attracted increasing attention in the past few years due to their high strength and chemical inertness, properties suitable for use as composites, electrode materials, and catalyst carriers. To improve the durability of PCNF as a catalyst for fuel cells, high-temperature heat treatment or silica coating methods are used. We would also like to determine whether heat treatment, silica coating, or both have any effect on improving the durability of PCNF, or whether the methods cause side reactions. The heating method is as follows: The obtained high-heat-treated PCNF was further heat-treated at 1700°C for 1 hour in a high-purity nitrogen stream. The ECSA of Pt/PCNF dropped to 30.6% of the initial value after 2000 cycles of potential cycling. However, Pt/Ht-PCNF and Pt/HtSi-PCNF ECSA showed a decline of 36.9% and 60.0%, respectively. In contrast, this study demonstrates that even as the density of the graphene layer increases, PCNF must provide many active sites at the carbon end of the sidewall of PCNF for adsorption of platinum nanoparticles. there is. In addition, it is believed that carbon corrosion caused by crystallization of amorphous carbon has been resolved. In this way, PCNF, which increases the supply of silica by increasing the degree of graphitization, is suitable for fuel cells and has improved durability.

Hybridizing engineering strategy of decatungstate III: Transition metal modified carbon quantum dot-regulated photo-catalytic oxidation performance of decatungstate

The selective oxidation of hydrocarbons (RH) by dioxygen (O2) is a very important method for industrial production of bulk oxygen-containing compounds, However, due to the high chemical inertness of RH and O2, achieving this reaction under mild conditions still faces significant challenges. This paper discloses an efficient hybridizing engineering (HE) strategy of decatungstate (DT) with 3d transition metal ions (Mn+=Ni2+, Co2+ or Cu2+)-modified carbon quantum dots (Mn+/CQD) as the dopants. Compared to pure CQD, The Mn+/CQD can more efficiently combine with DT anion to fabricate a high-quality hybrid via electrostatic interactions, thereby bestowing the hybrid with an enhanced visible light response especially the separation efficiency of photo-generated charge pairs. Furthermore, the above hybridization effects of Mn+/CQD on DT anion can be fine-tuned and gradually improved with a change of the metal ion from Cu2+, Co2+ to Ni2+, along with a continuous enhancement of the hybrid's photo-catalytic efficiency in the visible light- triggered selective oxidation of ethylbenzene with O2 in acetonitrile. The best Ni2+/CQD-doped TBADT can achieve ca. 48% ethylbenzene conversion and 87.6% acetophenone selectivity in the presence of 2 M HCl, and it also shows a much higher photo-catalytic activity for the photo-oxidation of toluene, cyclohexane and benzyl alcohol compared to pure TBADT. The HE strategy with Mn+/CQD as the cationized hybridizers is much superior to that with pure CQD or Ni2+ as the hybridizer in hoisting the photo-catalytic performance of DT.

Current-carrying friction behavior of CrN coatings under the influence of DC electric current discharge

CrN coatings are renowned for their low friction coefficients, high chemical inertness, excellent corrosion resistance, and substantial hardness, making them ideal for the tribological demands of bearings and gears in electric vehicles. This study investigated the current-carrying friction behavior of CrN coatings when sliding against steel balls under both non-electrified and electrified conditions. The friction coefficient (CoF), wear volume, wear type, and mechanism of the coating were reported by adjusting the direct current (DC) intensity and lubrication status. The findings indicate that while the current significantly exacerbates substrate wear during dry friction, its impact on the CrN coating is minimal. Even at a maximum DC current of 1.5 A, the wear rate of CrN coating during dry friction is only 1.9 × 10−4 mm3·(N·m)−1, representing a reduction by 79.1 % compared to the steel substrate. This effect is further pronounced when lubricated with PAO oil. The wear of CrN coating shows minimal change even as the current increased, and surface wear remains very slight. At a current of 1.5 A, the wear rate of CrN coating decreases to as low as 9.7 × 10−6 mm3·(N·m)−1, indicating a reduction by 98.7 % compared to its substrate. It is observed that under electrified conditions, the oxidation and degradation of CrN coating are accelerated, thereby resulting in the formation of a loose and low-hardness Cr2O3 oxide layer on the surface. The oxide layer is primarily attributable to the deterioration in frictional properties of the CrN coating under electrified conditions. Finally, CrN coatings exhibit minimal changes in tribological behavior under electrified conditions, thereby offering effective protection for substrates against electrical damage. Therefore, CrN coatings are ideal for applications involving electrical contacts.

A Polymer-Based Polar Stationary Phase Grafted With Modified Lysine for Hydrophilic Interaction Chromatography.

The high hydrophobicity and chemical inertness of poly(styrene-divinylbenzene) (PS-DVB) microspheres make their surface hydrophilic modification difficult. Here we describe a facile way to convert PS-DVB microspheres to hydrophilic, then can be used as polar stationary phase for hydrophilic interaction chromatography. This approach utilizes the grafting of an acrylamide-terminated lysine zwitterionic monomer onto PS-DVB microspheres via free radical polymerization. The obtained stationary phase shows good hydrophilicity and a typical retention mechanism of hydrophilic interaction chromatography toward several model polar analytes. It also exhibits obvious zwitterionic properties and is capable of separating cationic and anionic analytes simultaneously. The column shows negligible bleeding level, much superior to silica-based ones.

Structural Changes and Differences in Intrinsic Photoluminescence of Four Cationic Two-Dimensional Lead Halide Frameworks Modulated by Synthesis Temperature.

Luminescent hybrid organolead halide materials with cationic inorganic frameworks and high chemical inertness have demonstrated broad application prospects in the visible light region. However, the corresponding relationship between structural changes and luminescence properties in such materials needs further clarification. Here, for the first time, we have successfully synthesized [Pb2X3](PDAH)(H2O) (X = Cl or Br, PDAH = C7H4NO4) single crystals via a facile hydrothermal method and then obtained [Pb11X14](PDA)4 (X = Cl or Br, PDA = C7H3NO4) at higher temperatures. The different synthesis temperatures resulted in significant differences in the luminescence properties of the two groups of structures. X-ray crystallography revealed the different degrees of distortion of the PbII centers' coordination environment between the two structures, which would significantly affect the electron-phonon coupling process under excited states and ultimately affect the emission properties originating from self-trapped excitons (STEs) of the two materials. In addition, density functional theory (DFT) calculations indicate that the two structures have different band gap characteristics due to the different proportions of inorganic and organic components, which also affect the optoelectronic properties of the two groups of materials. It is also worth mentioning that the broadband orange-light emission of [Pb11Br14](PDA)4 with a high photoluminescence quantum efficiency (PLQE) of 86% endows it with potential applications in WLEDs.

Machinability of Ti6Al4V Alloy: Tackling Challenges in Milling Operations

This study investigates strategies for improving the 3D milling of Titanium Alloy Grade 5 (Ti6Al4V) by optimizing machining parameters and cutting tool engagement techniques. Ti6Al4V presents significant machining challenges due to its low machinability index (20%), which directly impacts manufacturing efficiency. High temperatures during machining, often exceeding 8820C, lead to phase transformations, creating a harder Beta lamellar equiaxed microstructure. This, coupled with the alloy's poor thermal conductivity, results in heat concentration at the cutting tool interface, accelerating thermo-chemical wear and potentially catastrophic tool failure. This study explores how controlled cooling methods, coupled with appropriate lubrication, can effectively dissipate heat and flush away chips, mitigating the detrimental effects of high temperatures. Furthermore, the selection of cutting tool materials and coatings with high thermal conductivity and chemical inertness, along with aggressive rake angles and higher relief angles, are examined as methods to improve shearing, minimize smearing, and enhance surface quality. By optimizing these parameters, this study aims to provide manufacturers with practical strategies to overcome the challenges of Ti6Al4V machining, ultimately increasing tool life and overall milling efficiency.

Application of Silicone in Ophthalmology: A Review.

This paper reviews the latest trends and applications of silicone in ophthalmology, especially related to intraocular lenses (IOLs). Silicone, or siloxane elastomer, as a synthetic polymer, has excellent biocompatibility, high chemical inertness, and hydrophobicity, enabling wide biomedical applications. The physicochemical properties of silicone are reviewed. A review of methods for mechanical and in vivo characterization of IOLs is presented as a prospective research area, since there are only a few available technologies, even though these properties are vital to ensure medical safety and suitability for clinical use, especially if long-term function is considered. IOLs represent permanent implants to replace the natural lens or for correcting vision, with the first commercial foldable lens made of silicone. Biological aspects of posterior capsular opacification have been reviewed, including the effects of the implanted silicone IOL. However, certain issues with silicone IOLs are still challenging and some conditions can prevent its application in all patients. The latest trends in nanotechnology solutions have been reviewed. Surface modifications of silicone IOLs are an efficient approach to further improve biocompatibility or to enable drug-eluting function. Different surface modifications, including coatings, can provide long-term treatments for various medical conditions or medical diagnoses through the incorporation of sensory functions. It is essential that IOL optical characteristics remain unchanged in case of drug incorporation and the application of nanoparticles can enable it. However, clinical trials related to these advanced technologies are still missing, thus preventing their clinical applications at this moment.

From nano to giant grains: Optimizing Pt thermistors for microbolometers

Pt is a suitable thermistor for use in microbolometers due to its high melting point, chemical inertness, and low 1/f noise. This work explores mechanisms of grain growth to fabricate Pt thin film thermistors for maximizing the temperature coefficient of resistance (TCR). The interplay between the microstructure and TCR is examined by varying Pt film deposition parameters, AlOX interlayer deposition technique, patterning technique, and annealing parameters. A smooth thin film morphology having giant grains of several hundreds of micrometers is achieved by abnormal grain growth, which is not attainable through normal grain growth. The fabrication of thermistor meanders is demonstrated through a combination of processes including Pt film deposition in O2/Ar environment, annealing at 1000 °C in Ar, and ion beam etching. Pt thermistors with a TCR (0 °C – 100 °C) of 0.371 ± 0.001 %/ °C are compatible with microbolometers utilizing carbon nanotube absorbers.

Mechanistic and Kinetic Insights into H2O Effects in the Conversion of C1‐C3 Hydrocarbons to Value‐added Products

The direct conversion of cheap and widely available C1‐C3 alkanes in natural gas/shale gas into building blocks for the chemical industry is highly attractive from an environmental perspective as a replacement for current oil‐based processes. Due to the high chemical inertness of these alkanes, but the high reactivity of the desired reaction products, which are easily involved in non‐selective sequential reactions, ongoing research activities are focused on controlling product selectivity through catalyst design and/or reactor operation. In this context, we have critically analyzed research studies dealing with the effect of steam or liquid water on catalyst activity and, in particular, on selectivity in the conversion of CH4, C2H6 and C3H8 to C2+‐hydrocarbons, formaldehyde, methanol, ethylene, acetic acid, and propene. In addition, our personal views on possible future developments are also given.

Nanosecond laser irradiation assisted chemical mechanical polishing (CMP) process for promoting material removal of single crystal 4H–SiC

Silicon carbide (SiC) is one of the most promising three-generation semiconductor materials owing to its remarkable properties and numerous potential applications. Nevertheless, the polishing efficiency of hard-to-process single-crystal SiC remains a significant challenge due to its high hardness and chemical inertness. A novel approach by employing nanosecond laser irradiation as a pre-process for the chemical mechanical polishing (CMP) process was presented. By irradiating the Si-face, the substrates were processed with CMP for a short time using normal 1 wt% diamond+ 99 wt% deionized water eco-friendly slurry. The performance of nanosecond laser irradiation assisted chemical mechanical polishing (NLIA-CMP), including material removal rate (MRR) and surface roughness (Ra), was evaluated. Besides, the possible effects were investigated. Atomic force microscopy (AFM) was used to observe the morphologies of SiC wafers after NLIS-CMP. The scanning electron microscopy (SEM) and the energy dispersive spectrometer (EDS) were used to characterize the surface morphologies and chemical composition of the SiC wafers treated with nanosecond laser. The results indicate that a highly efficient SiC-CMP with good surface quality can be realized by employing nanosecond laser irradiation as the pre-treatment and using an eco-friendly polishing slurry. The present study was a beneficial exploration of expanding the application of nanosecond laser to the CMP process.

Colloidal carbon soot templated TiO2/Ag surface functionalized 3D printed metal brushes as new generation surface enhanced Raman scattering substrates

This present work demonstrated the functional transformation of 3D printed metal substrates into a new family of Surface-enhanced Raman Scattering substrates, a promising approach in developing SERS-based Point-of-care (PoC) analytical platforms. l-Powder Bed Fusion (l-PBF, Additive manufacturing or 3D printing technique) printed metal substrates have rough surfaces, and exhibit high thermal stability and intrinsic chemical inertness, necessitating a suitable surface functionalization approach. This present work demonstrated a unique multi-stage approach to transform l-PBF printed metal structures as recyclable SERS substrates by colloidal carbon templating, chemical vapor deposition, and electroless plating methods sequentially. The surface of the printed metal structures was functionalized using the colloidal carbon soot particles, that were formed by the eucalyptus oil flame deposition method. These carbon particles were shown to interact with the metals present in the printed structures by forming metal carbides and function as an adlayer on the surface. Subsequent deposition of TiO2 onto these templates led to strong grafting of TiO2 and retaining the fractal structure of the soot template onto the metal surface. Electroless deposition of silver nanoparticles resulted in the formation of fractally structured TiO2/Ag nanostructures and these functionalized printed metal structures were shown as excellent SERS substrates in enhancing the vibrational spectral features of Rhodamine B (RhB). The presence of TiO2 photocatalyst on the surface was shown to remove the RhB analyte from the surface under photochemical conditions, which enables the regeneration of SERS activity, and the substrate can be recycled. The migration of metals from the printed metal structures into the fractally ordered TiO2/Ag nanostructures was found to enhance the photocatalytic activity and increase the recyclability of these substrates. This study demonstrates the potential of 3D-printed Inconel metal substrates as next-generation recyclable SERS platforms, offering a substantial advancement over traditional colloidal, thin-film, flexible, and hard SERS substrates.

Record-High Thermoelectric Performance in Al-Doped ZnO via Anderson Localization of Band Edge States.

Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco-friendly constituting elements. Here, adopting a unique synthesis route via chemical co-precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics ( 21.5µW cm-1 K-2 and 0.5 at 1100K in ) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi-dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnOthermoelectrics.

Study on nanosecond laser-induced iron plasma reactive etching of single-crystal CVD diamond

Single-crystal diamond has great potential applications in national defense, military, and aerospace fields. However, the high hardness, chemical inertness, and anisotropy bring great challenges to machine microstructures on the diamond. Here, iron plasma, generated by infrared nanosecond laser ablation of a Fe target, was utilized to etch single-crystal diamond. The EDS, Raman, and XPS analysis revealed the formation of iron carbide within the sputtered layer surrounding the diamond microgrooves, thereby confirming that the iron plasma reacts chemically with the diamond. It was observed that employing a reactive metal, such as iron, for etching diamond microgrooves yields improved morphological characteristics and enhanced etching efficiency compared to the use of a non-reactive metal, such as copper. Moreover, the process of material removal through laser-induced iron plasma etching of diamond was elucidated. Subsequently, a systematic investigation was conducted on the impact of processing parameters on the laser-induced iron plasma etching of diamonds. Various periodic microstructures with regular edges and no chipping and cracks were successfully processed on the diamond using suitable laser parameters. This study furnishes a novel approach for the efficient fabrication of high-quality microstructures on single-crystal diamonds.

Solar-assisted selective separation and recovery of precious group metals from deactivated air purification catalysts

The mitigation of environmental and energy crises could be advanced by reclaiming platinum group precious metals (PGMs) from decommissioned air purification catalysts. However, the complexity of catalyst composition and the high chemical inertness of PGMs significantly impede this process. Consequently, recovering PGMs from used industrial catalysts is crucial and challenging. This study delves into an environmentally friendly approach to selectively recover PGMs from commercial air purifiers using photocatalytic redox technology. Our investigation focuses on devising a comprehensive strategy for treating three-way catalysts employed in automotive exhaust treatment. By meticulously pretreating and modifying reaction conditions, we achieved noteworthy results, completely dissolving and separating rhodium (Rh), palladium (Pd), and platinum (Pt) within a 12-h time frame. Importantly, the solubility selectivity persists despite the remarkably similar physicochemical properties of Rh, Pd, and Pt. To bolster the environmental sustainability of our method, we harness sunlight as the energy source to activate the photocatalysts, facilitating the complete dissolution of precious metals under natural light irradiation. This eco-friendly recovery approach demonstrated on commercial air purifiers, exhibits promise for broader application to a diverse range of deactivated air purification catalysts, potentially enabling implementation on a large scale.

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS2 and multi-layer WS2/C coatings

The outstanding tribological performance of transition metal dichalcogenides (TMDs) is attributed to their unique sandwich microstructure and low interlayer shear stress. This advantageous structure allows TMDs to demonstrate exceptional friction reduction properties. Furthermore, the incorporation of TMDs and amorphous carbon (a-C) in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation properties. Amorphous carbon, known for its high ductility, chemical inertness, and excellent wear resistance, significantly contributes to the overall performance of these multi-layer coatings. To gain an in-depth understanding of the tribological mechanism and evolution of TMDs’ multi-layer coatings, a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman spectrometer. This innovative approach allowed for a comprehensive evolution of the tribological, topographical, and tribochemical characteristics of both single-layer WS2 and multi-layer WS2/C coatings in real time. The findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS2 coating and the multi-layer WS2/C coating. The single-layer WS2 coating predominantly experienced failure due to mechanical removal, whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS2/C coating. The tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior: the running-in stage, stable friction stage, re-deposition stage, and lubrication failure stage. Each stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

Achieving room temperature plasticity in brittle ceramics through elevated temperature preloading.

Ceramic materials with high strength and chemical inertness are widely used as engineering materials. However, the brittle nature limits their applications as fracture occurs before the onset of plastic yielding. There has been limited success despite extensive efforts to enhance the deformability of ceramics. Here we report a method for enhancing the room temperature plastic deformability of ceramics by artificially introducing abundant defects into the materials via preloading at elevated temperatures. After the preloading treatment, single crystal (SC) TiO2 exhibited a substantial increase in deformability, achieving 10% strain at room temperature. SC α-Al2O3 also showed plastic deformability, 6 to 7.5% strain, by using the preloading strategy. These preinjected defects enabled the plastic deformation process of the ceramics at room temperature. These findings suggest a great potential for defect engineering in achieving plasticity in ceramics at room temperature.

Two-dimensional tellurium nanosheet: A novel sensitive and stable surface-enhanced Raman scattering substrate

Two-dimensional (2D) materials with merits such as low cost, high chemical inertness and tunable electronic structure have become favorable candidates for next generation of surface-enhanced Raman scattering (SERS) platforms. However, the SERS sensitivity of 2D materials still needs to be improved and the large-scale synthesis methods should be developed to meet the requirements of practical applications. In this work, we explored performances of a brand-new SERS substrate made of 2D Te nanosheets (NSs), which exhibited thickness-dependent SERS properties, with thinner nanosheets yielding stronger SERS intensity. Under optimized conditions, the limits of detection (LODs) reached the order of 10−9 M combining with SERS enhancement factors (EFs) as high as 105 for copper phthalocyanine (CuPc) and methylene blue (MB). This impressive SERS performance could be attributed to the strong interaction and photoinduced charge transfer (PICT) processes between 2D Te NSs and molecules. Benefiting from the appropriate positions of valence band (VB) and conduction band (CB), the 2D Te NSs showed significant Raman enhancement for various molecules. Furthermore, the 2D Te NSs exhibited good air-stability for up to ∼2 months. These outstanding performances establish 2D Te NSs as a favorable SERS detection material with enormous potential in practical applications.

Diamond Based Optical Metasurfaces for Broadband Wavefront Shaping in Harsh Environment

AbstractMetasurface enables a new class of “meta‐optics” that can manipulate light at subwavelength scale. Despite that versatile metasurfaces have been demonstrated based on a wide range of materials, the vulnerability of conventional materials to harsh environments, i.e., low resistance to corrosion, low transparency at short wavelength, and lack of thermal/mechanical stability, greatly limit their applications in extreme conditions. Diamond is well‐known for exceptional properties, including the highest thermal conductivity, high damage resistance, extraordinary hardness, and chemical inertness. Therefore, diamond based metasurface is generally expected to benefit from its material merits for extreme use. However, the performance of diamond metasurface in harsh environments remains unexplored up to date. To address this question, this work is designed to study the suitability of single‐crystal diamond based metasurface for broadband applications under harsh environments. As an example, diamond metasurfaces with representative functionalities, including holographic wavefront‐shaping, DUV‐focusing, are investigated under high‐temperature, acid/alkali, and abrasive conditions, respectively. The findings prove the capability of diamond metasurfaces for applications in broadband and harsh conditions, which not only provides a practical and scalable scheme to encode on‐demand functionalities into diamond, but also unlocks a capable candidate to develop robust, large bandwidth, and durable meta‐optics for advanced wavefront shaping under extreme conditions.