ACS Applied Energy Materials最新文献

Presently, the exploration of novel inorganic lead-free perovskite scintillators has emerged as a prominent topic in the field of perovskite materials. Extensive attention has been garnered by materials such as Cs₃Cu₂I₅ due to their notable advantage in scintillation intensity, but the response time constants in the microsecond or even millisecond range severely constrain their potential applications in scintillators. In this study, large-sized (5–6 mm) CsAg₂I₃ single crystals with an ultrafast warm-white light emission on a nanosecond time scale are presented. Specifically, upon X-ray excitation, the single crystal demonstrates a broad-spectrum white light emission with a color temperature as high as 5129 K, attributed to its self-trapped exciton emission. The ¹³⁷Cs energy spectrum reveals that CsAg₂I₃ possesses an ultrafast response for γ rays with a time constant of 15 ns, which is significantly faster than that of Cs₃Cu₂I₅. Furthermore, time-resolved photoluminescence unveils a subnanosecond component with a response time of 0.9 ns. The characteristics of ultrafast warm-white light emission exhibit the significant potential of CsAg₂I₃ in radiation scintillation detection and its probability of playing a pivotal role in future radiation detection technology.

Benzonitrile radical cations generated in ionizing environments such as solar nebulae and interstellar clouds can react with neutral molecules such as acetylene to form a variety of nitrogen-containing complex organics. Herein, we present results from mass-selected ion mobility experiments and coupled-cluster and DFT calculations for the sequential reactions of acetylene with the benzonitrile radical cation (C₇NH₅^+•). The results reveal the formation of two covalently bonded adduct ions C₉NH₇^+• and C₁₁NH₉^+• with individual rate coefficients of 2.1(±0.4) × 10^–11 cm³ s^–1 and 1.1(±0.9) × 10^–11 cm³ s^–1, respectively measured at 334.5 K. The direct addition of acetylene onto the N atom of the benzonitrile cation results in the formation of a N-acetylene-benzonitrile^+• radical cation with a calculated collision cross-section of 67.5 Ų in perfect agreement with the measured cross-section of 67.5 Ų of the C₉NH₇^+• adduct. The measured collision cross-section of the second covalent adduct C₁₁NH₉^+• (72.2 Ų) is also in excellent agreement with the calculated cross-section (71.2 Ų) of the lowest energy isomer of the C₁₁NH₉^+• ion corresponding to the 2-phenylpyridine structure. The formation of the bicyclic 2-phenylpyridine radical cation is explained by the rapid conversion of the classical radical cation C₁₁NH₉^+• into a distonic ion structure that can efficiently cyclize in an exothermic transformation to form the 2-phenylpyridine radical cation. This intriguing mechanism could explain the formation of N-containing complex organics in different regions of outer space. The current results are expected to have direct implications for the search for nitrogen-containing complex organics in space.

Herein, we describe the development and application of a novel benzotriazole-based reagent toward radical trifluoroethoxylation. Various alkene classes, including styrene derivatives, enol carbonates, and allyl silanes, are viable reaction partners in this transformation, yielding diverse trifluoroethoxylated products. Furthermore, this method is readily applicable for the late-stage modification of natural product and drugs molecules. Mechanistic and computational studies suggest the intermediacy of an OCH₂CF₃ radical generated under photocatalytic conditions.

The liquid-phase catalytic oxidation of p-cymene to 4-methylacetophenone is an industrially significant reaction. However, the targeted oxidation of a specific C–H bond of p-cymene is extremely difficult due to there being many branched chains in p-cymene. In here, we designed a simple method to synthesize mesoporous LaCoO₃ catalysts with rich oxygen vacancy (O_ov) sites. The as-prepared mesoporous LaCoO₃ after 550 °C calcination (mLaCoO₃) exhibits remarkable catalytic activity for solvent-free oxidation of the p-cymene reaction, with a selectivity of over 80.1% selectivity for 4-methylacetophenone and a conversion of 50.2% for p-cymene (120 °C, 3 MPa). Besides, recycling studies have demonstrated that the mLaCoO₃ catalysts can be reused ten times in the aerobic oxidation of the p-cymene reaction without significant catalytic activity reduce. The experimental and characterization results indicated that the mesoporous structure of the catalyst is conducive to the generation of surface O_ov, which can properly facilitate ion spread during the catalytic process and afford enough O₂ for intermediate species, thus is beneficial for the generation of 4-methylacetophenone. This work demonstrates that the selectivity oxide p-cymene with an O₂ employing mLaCoO₃ catalyst is highly promising for chemical industrial applications.

Metal-dioxygen species are important intermediates formed during dioxygen activations by metalloenzymes in various biological processes, by catalysts in fuel cells, and prior to O₂ evolution by photosystem II. In this work, we focus on manganese-porphyrin complexes using tetramesitylporphyrin ligand (TMP) to explore changes in Mn K-edge X-ray absorption spectroscopy (XAS) associated with the formation of Mn-hydroxide and Mn–O₂ peroxide species. With limited spectroscopic characterization of these compounds, Mn K_β X-ray emission spectroscopy (XES), XAS, density functional theory (DFT), and time-dependent DFT (TD-DFT) analysis will enhance our understanding of their complex electronic structure. We show that the shape of the pre-edge in the K-edge Mn X-ray absorption near-edge structure (XANES) can serve as a spectroscopic signature of the Mn^III-peroxo formation and thus can be used to track the presence of the side-on peroxide as an intermediate in time-resolved or in situ experiments. Our results will help to further summarize the spectroscopic fingerprints for peroxo and hydroxo species, addressing the challenge of identifying the reactive metal species in catalytic reactions.

MXenes are a family of two-dimensional (2D) materials with broad and varied applications in biology, materials science, photonics, and environmental remediation owing to their layered structure and high surface area-to-volume ratio. MXenes have exhibited significant nonlinear optical characteristics, which have been primarily explored in the context of photonics applications, yet the second-harmonic generation (SHG) behavior of MXenes remains an unexplored aspect of their optical properties. Herein, we demonstrate and quantify large second-order responses of 2D Ti₃C₂T_x MXenes both in aqueous solutions and on a silicon substrate for the first time. MXene flakes showed strong second-harmonic scattering (SHS) in a dilute suspension with a sensitivity of less than 0.1 μg/mL. Angle-dependent SHS experiments further found that the second-order responses originate from coherent 2D dipole radiation. Through confocal and atomic force microscopies, we found that the intense SHG signal from free-standing MXene flakes increases exponentially with decreasing thickness, while two-photon fluorescence increases linearly with thickness. The second-order susceptibility of the MXenes was determined to be 3.6 pm V^–1 with a thickness of 10 nm, almost twice of that for an often-used SHG crystal, beta barium borate. We further explored surface properties of the MXene sheets by investigating the SHS responses upon addition of organic dye molecules to the system. It was found that the adsorption of crystal violet (CV) obeys a Langmuir adsorption model while the addition of malachite green (MG) resulted in almost no change in SHG intensity, even though the adsorption capacities for both CV (61.3 ± 1.7 mg/g) and MG (54.8 ± 2.8 mg/g) are similar. Such a stark difference in adsorption characteristics between cationic organic CV and MG dyes is likely due to their distinct orientational orderings on the MXene surfaces. This work opens many possibilities for the further employment of the family of 2D materials in photonics, optics, and surface catalysis applications.

The application of earth-abundant and low-toxicity iron catalysts as replacements for palladium in carbonylative coupling reactions remains challenging and largely unexplored. Reported here is a highly efficient iron-catalyzed carbonylation of aryl iodides with alkenyl boronic acids under ligand-free conditions, enabling the synthesis of α,β-unsaturated ketones even at atmospheric CO pressure. The broad applicability, including its effectiveness with α-branched enones and biologically active molecules, along with high yields and selectivity, underlines the general applicability of this catalytic system.

The structural and superconducting properties of the Bi-based superconductor Bi₂Rh₃(Se_1–xS_x)₂ were investigated over a wide pressure range. Bi₂Rh₃Se₂ is a superconductor with a superconducting transition temperature, T_c, of less than ∼1.0 K, whereas Bi₂Rh₃S₂ is a nonsuperconductor. The former shows a clear charge density wave (CDW) phase transition at 240 K and the latter shows a first-order structural phase transition at 165 K, providing the supercell structure. Both compounds have the same crystal structure at ambient temperature and pressure (monoclinic, space group of C2/m (No. 12)). This implies the possible formation of solid solution-like phases Bi₂Rh₃(Se_1–xS_x)₂. In this study, we prepared Bi₂Rh₃(Se_1–xS_x)₂ (x = 0–1.0) and investigated its superconducting properties and phase transitions at different x values. Because the superconducting properties and temperature causing the phase transition (T_pt) are quite different between Bi₂Rh₃Se₂ and Bi₂Rh₃S₂, their variation against x is quite intriguing from the viewpoint of the pursuit of physical properties via the replacement of Se with S. In this study, the features of the superconductivity and crystal structure against x were fully explored to depict the phase diagram. Moreover, we investigated the pressure (p) dependence of superconductivity and phase transition (CDW or the first-order structural transition) to clarify the interplay between the two ordered states.

Previous studies have reported that [PdAu₂₄(PA^F)₁₈]^2– (PA^F = 3,5-(CF₃)₂C₆H₃C≡C) with an icosahedral superatomic PdAu₁₂(8e) core underwent collision-induced sequential reductive elimination (CISRE) of 1,3-diyne (PA^F)₂ ( J. Phys.Chem. C 2020, 124, 19119). The most likely scenario after the CISRE of (PA^F)₂ is the growth of the PdAu₁₂(8e) core via the fusion of the Au(0) atoms produced from the Au₂(PA^F)₃ units on the core surface. Contrary to expectation, anion photoelectron spectroscopy and theoretical calculations regarding the CISRE products [PdAu₂₄(PA^F)_18–2n]^2– (n = 1–6) revealed that the electronically closed PdAu₁₂(8e) core does not grow to a single superatom with (8 + 2n)e but assembles with Au₂(2e) units. Characterization of the CISRE products of other alkynyl-protected Au clusters suggested that even the non-superatomic Au₁₇(8e) core was resistant to growth due probably to rigidification by PA ligands. We propose that there is a kinetic bottleneck in the growth process of protected Au clusters at the stage where they are electronically closed and/or lose their structural fluxionality by ligation.

Cyanate resin is widely used in electronic packaging, printed circuit boards, radomes, and communication satellites for its excellent dielectric performance, heat resistance, and good flame retardancy, but its high brittleness is still a real challenge to be solved. In this paper, three poly(ether sulfone)s (PESs) were prepared from bis(4-fluorophenyl)sulfone with different bisphenol compounds, namely, bis(allyl)bisphenol A (DABPA, PES-a), bisphenol fluorene (BHF, PES-b), and the mixture of DABPA and BHF (PES-ab). Then, the effects of PESs on the mechanical, thermal, and dielectric properties of 2,2′-bis(4-cyanophenyl)propane cyanate (BADCy) resins were investigated. The bulky fluorene ring and its intrinsic low dipole moment make PES-b an effective modifier to reduce the dielectric constant (ε) and dielectric loss (tanδ), as well as to improve the toughness of BADCy resin composites. The allyl units in PES-a can efficiently react with BADCy monomers, leading to a highly improved interfacial compatibility. The impact strength of the PES-b/BADCy (10/90, wt/wt) composites was increased to 23.8 kJ/m², which is 146% higher compared to the pure BADCy resin (9.7 kJ/m²), and the T_g was also increased slightly. More importantly, the ε and tanδ of PES-b/BADCy composites (7.5/92.5, wt/wt) are 2.51 and 0.0025, respectively, which are much lower than those of the pure BADCy (2.86 and 0.0054), at 10⁶ Hz. In the Ku-band range (12–18 GHz), the wave transmittance of PES-b/BADCy (5/95, w/w) composites reaches up to 92.5%-86.1% (14–18 GHz) compared with pure BADCy resins (87.9%-81%). The low-k dielectric properties, excellent wave-transparent properties, and highly enhanced toughness of the PES/BADCy composites have great potential for applications in microelectronics and aerospace.