Good Chemical Stability Research Articles

Synthesis, optical characterization and electrical behavior of chitosan/MgO/Cr2O3 nanocomposite for electrical applications

Magnesium oxide nanoparticles (MgO NPs) are straightforward, cheap, biocompatible, and biodegradable, making them one of the most popular inexpensive and non-toxic nanoparticles. In addition, Nanosized chromic oxide (Cr2O3) is a significant transition metal oxide due to its numerous exceptional attributes, it finds application in several domains. It has good electrical conductivity, excellent thermal and chemical stability. It is utilized in several industries for its ability to resist oxidation at high temperatures, as well as its application in refractory materials and catalysts. In this study, we utilized a laser ablation approach to synthesize a ternary nanocomposite composed of MgO and Cr2O3 nanoparticles as it is considered a clean method for the preparation of nanoparticles. Subsequently, these nanoparticles were integrated into Chitosan (CS) solution to create polymer nanocomposite via casting route. XRD confirmed the formation of Cr2O3 nanocrystals with size of 61 nm dispersed in chitosan/MgO matrix. FTIR verified the interactions between chitosan, MgO, and Cr2O3 nanoparticles. The broadening and shifting of the OH and NH bands with increasing Cr2O3 content confirms the interaction and complexation between Cr2O3 and Chitosan/MgO. UV–Vis analysis revealed that incorporating 7 wt% Cr2O3 reduced optical band gap from 5.59 eV for chitosan to 3.91 eV. The band gap values decreased with increasing Cr2O3 content due to polaronic defects. TGA showed improved thermal stability, with the 7 wt% Cr2O3 nanocomposite exhibiting a residual mass of 47 % at 700 °C compared to 28 % for chitosan. Dielectric studies demonstrated high dielectric constant and conductivity (10−5 S/cm at 10 Hz) values for the 7 wt% Cr2O3 nanocomposite, attributed to interfacial polarization effects and nanocapacitor formation by the conductive nanofillers. The ternary chitosan/MgO/Cr2O3 nanocomposites with tunable optical, thermal and electrical properties show promising potential for electronic applications.

Sulfonated cobalt phthalocyanine/NH2-MIL-125 heterojunction modified electrospun nanofiber membrane for emulsion separation and PMS-photocatalysis synergistic degradation

Membrane technology for wastewater remediation has generated significant interest, however, the single functionality, dull wettability and easy fouling property of the membrane hinder its practical application. Herein, a self-cleaning and multi-use superwetting nanofiber membrane was prepared by electrospinning and subsequent spraying technique. The sulfonated cobalt phthalocyanine/NH2-MIL-125 (CoPcS/NMIL) heterojunction was uniformly enrobed over polyethylene terephthalate (PET) electrospun membrane derived from waste PET bottles. The unique CoPcS/NMIL heterojunction exhibited a dual driving effect in photocatalytic activity and membrane wettability. Therefore, the fabricated CoPcS/NMIL@PET composite membrane demonstrated its capability to address complex water pollution issues effectively. The composite membrane exhibited notable flux permeation ability (538–3180 L m−2 h−1) and achieved excellent separation efficiency of over 99 % for diverse oil-in-water emulsions under the gravity filtration condition. Notably, the membrane can efficiently deal with stubborn high-viscosity crude oil fouling profiting from the photocatalytic self-cleaning function. A high flux recovery ratio of 93.6 % and a low irreversible fouling resistance ratio of 6.4 % can be obtained after 30 min of visible light irradiation. Impressively, CoPcS/NMIL@PET membrane exhibited enhanced permeation flux, separation efficiency and self-cleaning capacity compared to NMIL@PET membrane. Meanwhile, the CoPcS/NMIL@PET-activated peroxomonosulfate (PMS) system exhibited extremely high degradation performance for RhB under visible light with the degradation efficiency of 98 % within 10 min, suggesting its potential in the rapid purification of water-soluble organic pollutants. In addition, the CoPcS/NMIL@PET membrane has good chemical stability and mechanical properties for potential long-term use. Moreover, the demulsification mechanism in oil-water separation and PMS-photocatalysis synergetic mechanism over the fabricated CoPcS/NMIL@PET membrane were also investigated in detail. The research offers a promising approach for the design and fabrication of novel nanofiber membranes that incorporate photosensitizers and MOFs functional surfaces to address the challenges associated with such wastewater treatment.

Low-cost synthesis of Ti3C2Tx MXene-based sponge for solar steam generation and clean water production

MXenes are layered 2D materials with fascinating properties such as large surface area, good electrical conductivity, good chemical, and electrochemical stabilities, etc. However, the high cost of MAX phases remains a major bottleneck for the large-scale synthesis of Ti3C2Tx MXene for industrial applications. This motivated us to strategically design a method for the large-scale synthesis of Ti3C2Tx MXene using low-cost waste-derived precursors. Initially, we used carbon soot obtained from car exhaust as a low-cost carbon precursor for the synthesis of the Ti3AlC2 MAX phase. Further, the Ti3C2Tx MXene is synthesized from this MAX phase with better purity. Furthermore, the Ti3C2Tx MXene-activated carbon (AC) composite is prepared and coated over a natural biodegradable sponge (NBS) in order to use it as an efficient photothermal/solar absorber to produce steam using solar energy. The NBS layer exhibits a microporous structure that provides adequate water transportation and concentrated heat for interfacial water evaporation whereas the Ti3C2Tx MXene and AC provide large surface area and stability to the absorber. The Ti3C2Tx MXene-AC@NBS composite successfully produced solar evaporation rates of up to 1.8 kg m2/h with a solar steam conversion efficiency of 89.82 % with one sun solar irradiation.

Single-Crystal P2-Na0.67Mn0.67Ni0.33O2 Cathode Material with Improved Cycling Stability for Sodium-Ion Batteries.

Layered oxides constitute one of the most promising cathode materials classes for large-scale sodium-ion batteries because of their high specific capacity, scalable synthesis, and low cost. However, their practical use is limited by their low energy density, physicochemical instability, and poor cycling stability. Aiming to mitigate these shortcomings, in this work, we synthesized polycrystalline (PC) and single-crystal (SC) P2-type Na0.67-δMn0.67Ni0.33O2 (NMNO) cathode materials through a solid-state route and evaluated their physicochemical and electrochemical performance. The SC-NMNO cathode with a large mean primary particle size (D50) of 12.7 μm was found to exhibit high cycling stability leading to 47% higher capacity retention than PC-NMNO after 175 cycles at 1C rate in the potential window 4.2-1.5 V. This could be attributed to the effective mitigation of parasitic side reactions at the electrode-electrolyte interface and suppressed intergranular cracking induced by anisotropic volume changes. This is confirmed by the lower volume variation of SC-NMNO (ΔV ∼ 1.0%) compared to PC-NMNO (ΔV ∼ 1.4%) upon charging to 4.2 V. Additionally, the SC-NMNO cathode displayed slightly higher thermal stability compared to PC-NMNO. Both cathodes exhibited good chemical stability against air and water exposure, thus enabling material storage/handling in the ambient atmosphere as well as making them suitable for aqueous processing. In this regard, PC-NMNO was investigated with two low-cost aqueous binders, carboxymethyl cellulose, and sodium trimetaphosphate, which exhibited higher binding strength and displayed excellent electrochemical performance compared to PVDF, which could potentially lead to significant cost reduction in electrode manufacturing.

Simple and scalable preparation of lignin based porous carbon coated nano-clay composites and their efficient removal for the diversified iodine

Here, lignin and nano-clay were used to prepare novel composite adsorbents by one-step carbonization without adding activators for radioactive iodine capture. Specially, 1D nano-clay such as halloysite (Hal), palygorskite (Pal) and sepiolite (Sep) were selected as skeleton components, respectively, enzymatic hydrolysis lignin (EHL) as carbon source, lignin based porous carbon/nano-clay composites (ELC-X) were prepared through ultrasonic impregnation, freeze drying, and carbonization. Characterization results indicated lignin based porous carbon (ELC) well coated on the surface of nano-clay, and made its surface areas increase to 252 m2/g. These composites appeared the micro-mesoporous hierarchical structure, considerable N doping and good chemical stability. Results of adsorption experiments showed that the introduction of ELC could well promote iodine vapor uptake of nano-clay, and up to 435.0 mg/g. Meanwhile, the synergistic effect between lignin based carbon and nano-clay was very significant for the adsorption of iodine/n-hexane and iodine ions, their capacity were far exceed those of a single material, respectively. The relevant adsorption kinetic and thermodynamics, and mechanism of ELC-X composites were clarified. This work provided a class of low-cost and environmentally friendly adsorbents for radioactive iodine capture, and opened up ideas for the comprehensive utilization of waste lignin and natural clay minerals.

An Organodiphosphate-Containing Polyoxoniobate Ring and Its Assembly into a Three-Dimensional Framework through Hydrogen Bonding.

In this work, a novel organodiphosphate-containing inorganic-organic hybrid polyoxoniobate (PONb) ring {(PO3CH2CH2PO3H)4Nb8O16}4- (Nb8P8) has been achieved by a one-pot hydrothermal method. The ring is constructed from a tetragonal {Nb8O36} motif and four {PO3CH2CH2PO3H} ligands. Interestingly, Nb8P8 can be joined together via K-H2O clusters {K2(H2O)4(OH)2} to form one-dimensional chains {[K2(H2O)4(OH)2]Nb8P8}n and further linked by {Cu(en)2}2+ (en = ethylenediamine) complexes, resulting in a three-dimensional supramolecular framework {[Cu(en)2]2[K2(H2O)4(OH)2]Nb8P8}·3en·H2O (1). 1 exhibits good chemical and thermal stability and has a high water vapor adsorption capacity of ≤224 cm3 g-1 (22.71 mol·mol-1) at 298 K, outperforming most of the known polyoxometalate-based materials. Impedance measurements prove that 1 can transfer protons with moderate conductivity. This study not only contributes to the structural diversity of organodiphosphate-containing PONbs and PONb rings but also provides a reference for the development of PONb-based materials with unique performance.

Bevel-edge epitaxy of ferroelectric rhombohedral boron nitride single crystal.

Within the family of two-dimensional dielectrics, rhombohedral boron nitride (rBN) is considerably promising owing to having not only the superior properties of hexagonal boron nitride1-4-including low permittivity and dissipation, strong electrical insulation, good chemical stability, high thermal conductivity and atomic flatness without dangling bonds-but also useful optical nonlinearity and interfacial ferroelectricity originating from the broken in-plane and out-of-plane centrosymmetry5-23. However, the preparation of large-sized single-crystal rBN layers remains a challenge24-26, owing to the requisite unprecedented growth controls to coordinate the lattice orientation of each layer and the sliding vector of every interface. Here we report a facile methodology using bevel-edge epitaxy to prepare centimetre-sized single-crystal rBN layers with exact interlayer ABC stacking on a vicinal nickel surface. We realized successful accurate fabrication over a single-crystal nickel substrate with bunched step edges of the terrace facet (100) at the bevel facet (110), which simultaneously guided the consistent boron-nitrogen bond orientation in each BN layer and the rhombohedral stacking of BN layers via nucleation near each bevel facet. The pure rhombohedral phase of the as-grown BN layers was verified, and consequently showed robust, homogeneous and switchable ferroelectricity with a high Curie temperature. Our work provides an effective route for accurate stacking-controlled growth of single-crystal two-dimensional layers and presents a foundation for applicable multifunctional devices based on stacked two-dimensional materials.

A new green approach to synthesizing MIP-202@porous silica microspheres for positional isomer/enantiomer/hydrophilic separation

Metal-organic frameworks (MOFs) with superior physicochemical properties have great potential for applications in chromatographic separation. However, currently popular methods for the synthesis of MOF-based silica composite materials usually require the use of harmful organic solvents and long-term high-temperature sealing reactions. In order to respond to the needs of green chromatography, it is urgent to develop a new green organic-solvent-free strategy for the synthesis of MOF@SiO2 composites. MIP-202 is a zirconium-MOF constructed from zirconium ion and L-aspartic acid, which features green synthesis as well as good hydrolytic stability and chemical stability. In this paper, SiO2-NH2 was first prepared in a hydrophilic deep eutectic solvent, and then an amino acid-based MOF material (MIP-202) was modified on the surface of the SiO2-NH2 in an aqueous solution to obtain a MIP-202@SiO2 composite material. The multi-mode separation performance of MIP-202@SiO2 as a promising liquid chromatographic stationary phase was particularly evaluated and the separation mechanisms were discussed. The MIP-202@SiO2 column exhibited excellent separation ability for aromatic positional isomers. In addition, chiral enantiomers and hydrophilic analytes were also satisfactorily detected and separated. This work provides a new approach for the facile synthesis of MOF-based liquid chromatographic separation material by using green deep eutectic solvent and water as the reaction media.

Achieving high energy storage performance in PbHfO3-based antiferroelectric ceramics by Sr element doping

Antiferroelectric (AFE) ceramics are the most promising material system for energy storage in dielectric capacitors due to their fast charging-discharging rate, good chemical stability, and high energy storage density. However, it is exceedingly challenging to simultaneously achieve the excellent recoverable energy density (Wre) and high energy storage efficiency (η) at present. In this work, (Pb0.925-xSrxLa0.05)(Hf0.95Ti0.05)O3 AFE ceramics with various Sr contents are fabricated by solid-state sintering processing. It has been found that Sr-doping in the A-site can significantly affect the microstructure, including reducing grain size and modulation period, effectively strengthening the antiferroelectricity, which is responsible for the improved energy storage performance. The high recoverable energy storage density of 10.2 J/cm3 is obtained at 560 kV/cm with an ultra-high efficiency of 93.0% in (Pb0.875Sr0.05La0.05)(Hf0.95Ti0.05)O3 ceramics. These features suggest that Sr-doped PbHfO3-based AFE ceramics can serve as promising candidates for capacitor materials, offering significant potential in the realm of energy storage applications.

Recent Advances in the Strategies of Simultaneous Enzyme Immobilization Accompanied by Nanocarrier Synthesis

In recent years, with advancements in nanotechnology and materials science, new enzyme immobilization strategies based on nanomaterials have continuously emerged. These strategies have shown significant effects on enhancing enzyme catalytic performance and stability due to their high surface area, good chemical stability, and ease of enzyme binding, demonstrating tremendous potential for industrial applications. Those methods that can rapidly synthesize nanocarriers under mild conditions allow for the one-step synthesis of nanocarriers and enzyme complexes, thereby exhibiting advantages such as simplicity of process, minimal enzyme damage, short processing times, and environmental friendliness. This paper provides an overview of simultaneous enzyme immobilization strategies accompanied by nanocarrier synthesis, including organic–inorganic hybrid nano-flowers (HNFs), metal–organic frameworks (MOFs), and conductive polymers (CPs). It covers their preparation principles, post-immobilization performance, applications, and existing challenges.

Enhancing the efficacy of monolaurin against SARS-CoV-2 and influenza A (H1N1) with a nanoemulsion formulation

Monolaurin was utilized to formulate temperature-driven phase inversion nanoemulsions containing lesser galangal essential oil, fixed oil, and Cremophor RH40, with aim for eradicating enveloped viruses. Results showed that the droplet size of the nanoemulsion depended on lesser galangal essential oil–fixed oil ratio, monolaurin concentration, and oil concentration. Nanoemulsions prepared from lesser galangal essential oil–perilla oil (60:40) exhibited approximately 50-nm nanosized droplets and high entrapment efficiency (98.68 % ± 2.45 %). After storage at 25 °C for 1 year, droplet size did not vary significantly from the initial size, and monolaurin content was >95 %, indicating good physical and chemical stability. The monolaurin was located at the oil–water interface as indicated by a two-dimensional nuclear Overhauser effect nuclear magnetic resonance spectroscope and computer simulation. The 0.2% w/v monolaurin nanoemulsion inhibited SARS-CoV-2 and influenza A (H1N1) viruses with efficacy more than 3 log reduction (99.90 %) and low cytotoxicity. Hence, the monolaurin nanoemulsion can successfully eradicate enveloped viruses, especially SARS-CoV-2 and influenza A (H1N1).

MoSe2 with Ultra-Fine Pt Decoration for Efficient Photodegradation

Transition metal dichalcogenides are widely studied for their photocatalytic ability due to the adjustable bandgap, high carrier mobility and possibility of foreign-element doping. In this work, multilayer molybdenum diselenide (MoSe2) was decorated with ultra-fine Pt nanoparticles through the mild hydrothermal method. MoSe2-Pt nanocomposites were synthesized and showed good structural and chemical stabilities. The incorporation of Pt nanoparticles provides plenty of active sites for MoSe2. The dominant Pt particle sizes are 1.8 nm, 1.8 nm, and 1.9 nm for the three synthesized samples, respectively. The mean crystal sizes of Pt (111) were calculated from X-ray diffraction patterns and we found that they were in accordance with the particle sizes. Both the particle sizes and mean crystal sizes are related to the synthesis conditions. X-ray photoelectron spectroscopy (XPS) characterizations revealed the formation of Se–Pt bonding. The relative contents of Pt–Se bonding were also calculated from XPS results, and they show the same trends as the optical absorption properties. Combining the XPS and optical absorption results, the effects of Se–Pt bonding during the photo-related process could be further confirmed. By degrading methylene blue (MB) under visible light, the synthesized nanocomposites proved promising for application in real-case degradation of organic pollutants. The sample synthesized with a moderate content of MoSe2 exhibited the best photodegradation efficiency, which could be explained by the maximum Pt-Se contents. Based on the experimental findings, we proposed a possible photodegradation mechanism.

Evaluation of Physico-Chemical Characteristics of Cement Superplasticizer Based on Polymelamine Sulphonate.

Cementitious materials are used to construct an engineered barrier in repositories for radioactive waste. The cement matrix may contain a variety of organic compounds, some of which are polymeric admixtures used as plasticizers. Superplasticizers (SPs) are highly effective organic cement additives for reducing water amount, increasing workability, homogeneity, plasticity and the non-segregation of mortars and grouts, improving mechanical properties and resistance to destructive environments. SPs in cement could have an impact on the long-term safety of the disposals of radioactive waste. These organic agents can leach from the cementitious matrix into groundwater and may affect the migration behaviour of radionuclides. The detailed chemical composition and other characteristics of the cement (CEM I 42.5 R, Sweden) used for the leaching experiments were evaluated. It contained mainly CaO (52.51 ± 1.37, %), and the surface area of the cement particles was 13.2 ± 1.3 m2/g. An insignificant increase in pH (from 12.6 ± 0.1 to 12.8 ± 0.1) was observed for the leachates over 10 days. A commercially available cement superplasticizer based on polymelamine sulphonate (PMS) Peramin SMF10 (Peramin AB, Sweden) was chosen for the research. The product's chemical composition was analysed using wavelength-dispersive X-ray fluorescence (WD-XRF) spectroscopy, while other physico-chemical properties of the PMS superplasticizer were assessed by Raman spectroscopy and thermo-gravimetric analysis. In aqueous solutions and powders of PMS, the same most intensive features were observed at 774 cm-1 (ring out-of-plane deformation), 977 cm-1 (C-N-C bending, SO stretching) and 1055 cm-1 (C-N=C bending) in the Raman spectra. At up to 270 °C, the polymer was thermally stable. Raman and UV/Vis spectroscopies were used to assess the rate of the alkaline degradation of PMS superplasticizer in different aqueous solutions. No changes were observed in the hydrolytic solutions with any of the above analytical methods over a period of 3 years. The results obtained revealed a good thermal and chemical stability (in highly alkaline media, pH = 9.9-12.9) of the PMS polymer.

Enhanced photoreduction of U(VI) in solution by Ti3C2Tx/g-C3N4 composites

The enhanced transfer efficiency of electron from photocatalyst to U(VI) is crucial for U(VI) photoreduction. Herein, we developed porous 2D/2D Ti3C2Tx/g-C3N4 heterojunction structure through the pyrolysis gasification of urea during direct calculation of Ti3C2 nanosheet and urea. Ti3C2Tx/g-C3N4 hybrid displayed the exceptional photocatalytic performance, high reaction rate constant (k1 = 0.0228 min−1) and rapid removal kinetics due to high photocatalytic activity, good chemical stability and highly efficient separation of photo-generated electron-hole pairs. According to quenching experiments and ESR analysis, the superoxide (.O2-) radicals played an important role in U(VI) photoreduction by Ti3C2Tx/g-C3N4. The higher efficient migration of photo-generated electrons from g-C3N4 to Ti3C2 co-catalyst was attributed to the tight interfacial interaction of –NHx of g-C3N4 with Ti3C2 via NHx-Ti chemical bonding, which increased the photoreduction of U(VI) into U(IV) by XPS analysis. The findings are crucial for designing g-C3N4-based catalysts by manipulating electronic structure for enhanced U(VI) photoreduction.

RbxCsyWO3 based superhydrophobic transparent thermal insulation film for energy saving

Superhydrophobic transparent insulation film has attracted more attentions in the field of energy-saving glass due to its excellent near-infrared (NIR) shielding property and good self-cleaning performance. In this study, Rb+, Cs+ co-doped tungsten bronze powders were synthesized through a solvothermal reaction, and the superhydrophobic transparent thermal insulation film was constructed on glass. Results show that the strategy of Rb+, Cs+ co-doping can improve the NIR shielding property by incorporating more alkali metal ions into the hexagonal channel and can increase the content of W5+. When n(Rb)/n(Cs)=2, the film exhibits the best NIR shielding performance, with a visible transmittance of 55.6% and an NIR shielding rate of 94.6%. The superhydrophobic tungsten bronze film was successfully prepared with a water contact angle of 163.3±4.1°. The film also exhibits good chemical stability and water impact resistance, with a visible light transmittance of 62.7%, and an NIR shielding rate of 92.9%. The maximum temperature difference in insulation between the uncoated glass and the glass coated with R2WO's PVA/PDMS/SiO2-2 film is 8.9℃ under the irradiation of a tungsten lamp. In conclusion, R2WO's PVA/PDMS/SiO2-2 film, which exhibits excellent heat insulation and good self-cleaning ability, holds great potential for application in the energy-saving glass industry.

Recyclable and dual-functional Ag3PO4/3D graphene aerogel photocatalysts for simultaneous water oxidation and pollutant degradation

Exploiting recyclable and reusable photocatalysts in pollutants elimination and water splitting has drawn extensive research attention for solving the increasing energy and environmental issues. Herein, we designed a high-performance dual functional Ag3PO4/three-dimensional (3D) graphene aerogel (APGA) photocatalyst, in which the 3D GA with extremely lightweight and high mechanical stability served as the support for Ag3PO4 particles, preventing the serious weight loss during the recovery process. Moreover, different from the traditional powder photocatalysts, the application of 3D GA support avoided the secondary contamination caused by the catalyst residue during the reaction. The abundant hydroxyl groups on the surface of porous 3D GA prevented the aggregation of Ag3PO4 particles, forming a close interfacial contact. Profiting from the large number of active sites and high conductivity of 3D GA, the optimized APGA-12 sample showed excellent O2 generation (814.1 μmol·g−1) and synchronous Cr (VI) reduction (87.5 %) efficiency. In addition, the APGA-12 sample also exhibited excellent carbamazepine (CBZ) degradation activity (99 % within 30 min) in the presence of peroxymonosulfate (PMS). Cycling experiments combined with the scaled-up reactions verified the good mechanical and chemical stability of APGA samples. This work provided a promising strategy for solving the problems of catalyst recycling in the field of pollutant degradation and water oxidation.

Pure CaF2 crystal for fast neutron detection

Pure CaF2 crystals have been widely used for optical functional crystals due to their good optical properties, mechanical properties, and chemical stability. This study discovered the crystal's pulse shape discrimination (PSD), proving it a promising scintillator for fast neutron detection via the 40Ca neutron capture reaction. Luminescence emission spectra were studied by X-ray luminescence measurements. The maximum emission peak was observed between 250 and 300 nm, corresponding to self-trap exciton emission. The crystal response to gamma, alpha, and neutron were studied under 137Cs, 241Am, and 252Cf radiation sources, respectively. The difference in gamma and alpha decay times enabled the PSD capability of pure CaF2. Large neutron reaction cross-sections, PSD capability, and good chemical stability make pure CaF2 crystal candidates for fast neutron beam monitoring detectors. Moreover, the crystal can be used for 40Ca(n,p)40K and 40Ca(n,α)37Ag neutron capture cross-section study.

Promoting energy transfer pathway in porphyrin-based sp2 carbon-conjugated covalent organic frameworks for selective photocatalytic oxidation of sulfide

The sp2 carbon-conjugated covalent organic frameworks (COFs) with fully π-conjugated lattice and high chemical stability are promising heterogeneous photocatalysts. Herein, we report the design and synthesis of a novel palladium (Pd) porphyrin-based sp2 carbon-conjugated COF (PdPor-sp2c-COF) with an eclipsed AA stacking 2D structure. Interestingly, PdPor-sp2c-COF showed high crystallinity, good chemical stability, and a broad absorption of visible light. Moreover, compared to our previously reported metal-free Por-sp2c-COF, PdPor-sp2c-COF displays an improved photocatalytic performance in the selective aerobic oxidation of sulfides under green light irradiation. The systematic mechanistic studies testified that the enhanced photocatalytic activity can be ascribed to promoting energy transfer pathway over PdPor-sp2c-COF. Our study clearly demonstrates that it is favorable to promote the energy transfer pathway in sp2 carbon-conjugated COFs by using metalloporphyrin-based molecular building blocks. This work will inspire us to design and synthesize novel photocatalysts based on COFs for the selective aerobic oxidation.

Moisture‐Resistant Orange Emitters with Near‐Unity Quantum Yield from Mn2+ Alloyed Vacancy‐Ordered Quadruple Perovskites

AbstractMn2+‐doped metal halide perovskites present remarkable optical properties in optoelectronic applications, although the realization of high efficiency and stability is still a challenge. In this work, a series of highly efficient and stable orange‐emitting Mn2+ alloyed Cs4Cd1‐xMnxBi2Cl12 single crystals are successfully synthesized via a hydrothermal reaction. Combined with the crystal structure and spectral characterization at 7 K, the site occupation of Mn2+ and defect emission are systematically discussed. Benefiting from the effective [BiCl6]3−→[MnCl6]4− energy transfer and lattice distortion, these single crystals exhibit a maximum internal and external quantum yield of ≈97% and ≈65% at 35% heavy doping level. Interestingly, these Mn2+‐alloyed single crystals exhibit remarkably waterproof stability, no decrease in emission intensity is observed after immersion in deionized water for 4 h. After soaking in deionized water for 100 days, the internal quantum yield can still maintain 44%, implying good chemical stability and moisture resistance due to the formation of protective BiOCl layer. This work provides new insights into the optimization mechanism for Mn2+ luminescence and overcoming the downside of their waterproofing in humid conditions.

Temperature-relevant degradation in amorphous carbon coated SS316L bipolar plates for PEMFC

The corrosion of metallic Bipolar Plates (BPs) has become a key bottleneck in the practical application of proton exchange membrane fuel cells (PEMFCs). Environmental factors inside the PEMFCs significantly accelerate the degradation of electrical conductivity and durability of metallic BPs. In this work, we investigated the corrosion behavior and conductive properties of amorphous carbon coating (a-C) coated SS316L in a simulated PEMFC environment at various operating temperatures. The results showed that the corrosion current density (Icorr) of a-C varied in a range of 2.3–8.7 nA/cm2 when subjected to a temperature range of 40–80 °C. Additionally, the interfacial contact resistance increased from 4.36 to 9.56 mΩ/cm2 with a rise in temperature. The reasons could be ascribed to two aspects. First, the a-C maintained the good chemical stability of sp2/sp3 bonds regardless of temperature changes, favoring remarkable anti-corrosion and good conductivity. Second, the higher temperatures intensified the penetration of corrosive species, accelerating the dissolution process of a-C coated SS316L and leading to substantial corrosion failure.