Progress in Solid State Chemistry最新文献

Polyoxometalates (POMs) and their composites have emerged as promising candidates for degrading toxic chemical dyes in wastewater remediation. POMs, with their tunable structures and redox properties, exhibit high catalytic activity towards various organic pollutants, including dyes. The integration of POMs into composite materials creates a synergistic effect that enhances endurance and efficiency during dye degradation. POMs are classified based on metal composition and structure, highlighting their roles in dye removal processes. Categories include molybdenum-based, tungsten-based, vanadium-based, and mixed metal-based POMs, each with distinct properties affecting dye elimination efficacy. The application of POMs and their composites in degrading specific chemical dyes, including cationic, anionic, and azo dyes, is elaborately described. Various mechanisms for dye removal from aqueous media, such as photocatalysis, adsorption, Fenton-like reactions, and electrochemical processes, underscore the crucial role of POMs and their composites in toxic chemical dye degradation. The factors influencing dye-POM interactions, such as pH, temperature, POM composition, and dye structure, are analyzed to understand their impact on removal efficiency. The review discusses the influence of metal type, POM structure, and solution conditions on dye removal efficacy, providing insights into how specific metal-based POMs interact with different dye molecules. Challenges and future perspectives for implementing POM-based materials in dye wastewater treatment are outlined, emphasizing the need for further research to optimize performance and ensure practical feasibility in large-scale applications.

Currently, the development of single-phase white emitters is an interesting research topic. Researchers have paid much attention to tune white-emitting of Dy³⁺-activated phosphors via Tm³⁺ sensitization strategy. However, the role of Tm³⁺ sensitization on luminescence thermostability was usually underestimated. Herein, color-tunable germanate phosphors Ba₂Y₂Ge₄O₁₃ (BYGO):Tm³⁺,Dy³⁺ were prepared. The white light emission is achieved due to the effective energy transfer from Tm³⁺ to Dy³⁺. A BYGO:Tm³⁺,Dy³⁺-based w-LED exhibits warm white-emitting. Moreover, the back-energy transfer of Dy³⁺→Tm³⁺ contributes to the improvement of luminescence thermal stability. Meanwhile, the difference of temperature-dependent Tm³⁺ and Dy³⁺ emissions realizes satisfactory temperature sensing properties. This work provides a deep understanding for the role of Tm³⁺ sensitization strategy on color tuning and thermostable improvement, promoting multifunctional utilizations of Dy³⁺-activated phosphors.

Titanium Nitride (TiN) is widely used in many industrial sectors for its outstanding performances including its mechanical properties, high chemical and thermal stability. Associated with its plasmonic behavior, TiN thin films are very promising for the manufacturing of optical metasurfaces devices or new plasmonic materials. Among the processes that make it easy to obtain metal nitride coatings, nitriding of metal oxide films has become increasingly popular in recent years. A multitude of synthesis processes can be used to obtain TiO₂ films, with different crystalline states (amorphous, anatase or rutile) depending on the technique used, which can then be converted into TiN coatings. In this paper, the effect of the initial crystalline state of TiO₂ layers was investigated on the structural properties, plasmonic properties and the friction behavior of TiN thin films obtained by Rapid Thermal Nitridation (RTN). The results indicate that, regardless of the crystalline state of the starting TiO₂ film, the RTN process leads to complete nitridation of TiN coating. Moreover, even though surface morphology and friction properties differ slightly, depending on the crystallization of the starting TiO₂, plasmonic properties remain very similar, thus highlighting the great versatility and uniformity of this nitriding technique, enabling TiN to be produced for a wide range of applications.

Among the Material of Institute Lavoisier (MIL) compounds, MIL-125 has been proved to be potentially high photoactive electrode in the photoelectrochemical (PEC) devices. The great progress has been achieved in the preparation, structural optimization and applications of MIL-125, especially in the PEC technology, as witnessed by the quick increase in the number of published papers. Consequently, a comprehensive review of the current research status of MIL-125 based electrodes in PEC is warranted. This review provides an in-depth analysis of various PEC applications employing MIL-125 based photoelectrodes, such as sensing (including PEC biosensors, organic pollutant detection, and heavy metal ion sensing), water splitting for hydrogen production, photovoltaic cells (including dye-sensitized solar cells, quantum dot-sensitized solar cells, perovskite solar cells, and organic solar cells), photoelectrocatalysis, and photocathodic protection. Particular emphasis is placed on the signal amplification strategies, modification design, and reaction mechanisms of MIL-125 for PEC applications. Finally, the development opportunities and unsolved challenges associated with MIL-125 based materials in the PEC field are also highlighted. This comprehensive review is expected to expand the knowledge of recent advancements in MIL-125 and its derivatives modified electrodes and encourage researchers to promote the construction of efficient PEC systems.

Transition metal nitrides (TMNs), in some cases referred as metallic ceramics, have unique physical and chemical properties, thanks to their ceramic-metallic nature, and are considered an attractive alternative to noble metals for electrochemical processes. In particular, theoretical work predicts TMNs as promising electrocatalysts towards the nitrogen reduction reaction (NRR). However, recent experimental studies under realistic conditions, have shown the release of lattice nitride to ammonia in a noncatalytic process, suggesting inherent instability of these materials. TMNs stability can be increased by the incorporation of a second metal in the lattice, to form bimetallic systems. Herein, we present a robust approach to prepare nonprecious transition multi-metallic nitride nano-catalysts, followed by a comprehensive study on their stability. The stability of the as-prepared catalysts was tested in electrolytes relevant for electrocatalysis, showing a higher chemical resistance of the bimetallic catalysts over the monometallic ones. This study suggests a novel approach to matching electrolyte pH and catalyst to ensure chemical stability in the electrochemical environment.

This article investigates the densification of AlN ceramics through both Gas Pressure Sintering (GPS) and Spark Plasma Sintering (SPS) methods, employing cerium aluminates (CeAlO₃) as sintering aids and comparing their influence to that of the usual cerium oxide (CeO₂). While sintering aids like CeO₂ promote densification, CeAlO₃ exhibited lower reactivity during both SPS and GPS sintering. Chemical reactions between cerium oxide and aluminium oxide primarily involved the reduced phase as cerium sesquioxide (Ce₂O₃). On the basis on the Ce₂O₃–Al₂O₃ pseudo-binary system, the formation of secondary phases, such as CeAlO₃ and CeAl₁₁O₁₈, during sintering was explained and confirmed by XRD. From complementary characterizations, it has been shown that sintering significantly impacted secondary phase composition and distribution. By employing specific densification cycles, SPS yielded smaller grains and thicker secondary phase cordons which led to enhanced electrical conductivity. Conversely, GPS produced coarser microstructures including larger grains and a network of secondary phases and some agglomerations at the triple points. These modifications influenced the overall conductivity. SPSed samples with 3 wt.% CeO₂ and short dwelling times demonstrated higher electrical conductivity, exceeding by about 6 orders of magnitude the electrical conductivity of those obtained by GPS.

We present a range of inverse perovskite nitrides with an elpasolite-type superstructure. (Ca₃N_0.682(9))Sn and (Ca₃N_0.559(7))Pb are variants of the previously described (Ca₃N)Sn and (Ca₃N)Pb which contain less nitrogen and crystallize in $Fm\bar{3}m$. (Ba₃N_0.5)Sn and (Ba₃N_0.5)Pb resemble the previously reported perovskites (Ba₃N_x)Sn and (Ba₃N_x)Pb, but with both the superstructure and octahedral tilting, resulting in space group $R\bar{3}$. (Ca₃N_0.77(2))Si, (Ca₃N_0.669(6))Ge, (Sr₃N_0.5)Ge and (Ba₃N_0.5)Ge all crystallize in P2₁/n. Among these, only (Ca₃N_x)Ge has been previously described as (Ca₃N)Ge. (Ca₃N_0.77(2))Si is notably the first compound in which mutually isolated N³⁻ and Si⁴⁻ ions coexist. There also exists a version with composition (Ca₃N_0.86(6))Si, which crystallizes in the cubic perovskite aristotype structure with space group $Pm\bar{3}m$. Similarly, there are versions of (Sr₃N_0.5)Ge, (Ba₃N_0.5)Sn and (Ba₃N_0.5)Pb with elevated nitrogen contents, less strongly tilted octahedra and no apparent superstructure. Electronic structure calculations indicate a metallic nature of the title compounds, with rather narrow improper band gaps for the strontium and barium compounds.

From crystal chemistry and density functional theory DFT calculations, a stepwise rationale is proposed for the transformation from standalone distorted tetrahedron α-C₅ favored over standalone regular tetrahedron β-C₅ to high density – ultra hard orthorhombic α-C₆ and β-C₆ with qtz (quartz-based) topology characterized by 3D arrangements of distorted tetrahedra to lower density dia-C topology (diamond-like, with regular C4 tetrahedra). Progressive C insertions into orthorhombic α-C₅, α-C₆, and lastly into C₇ were operated leading to ultimate C₈ stoichiometry identified as diamond-like. C₇ was also used as template to devise C₃N₄ carbonitride with exceptional mechanical properties. The induced structural and physical changes are supported with elastic properties pointing to ultra-hardness, larger for qtz α,β-C₆ than dia C₈ and inferred dynamic stability for all stoichiometries from the phonons band structures. The thermodynamic quantities as the specific heat were compared with diamond experimental C_V. The electronic band structures reveal semi-conducting C₆, metallic C₇ characterized by diamond-defect structure, and insulating C₈. The results are meant to help further systemic understanding of tetrahedral carbon allotropes.