Gonzalesfitch4424

Metal-organic frameworks (MOFs) have been a promising material for many applications, e.g., photocatalysis, luminescence-based sensing, optoelectronics, and electrochemical devices, due to their tunable electronic properties through linker functionalization. In this work, we investigate the effect of mixed organic linkers on the bandgap modulation of polymorphic zirconium-based MOFs, UiO-66 and MIL-140A using density functional theory (DFT) calculations. We show that the electronic properties of both MOFs are in contrast to Vegard's law for semiconductors, that is, mixed-linker systems exhibit bandgaps not intermediate within the range of single-linker systems. Calculations of the total and partial density of states revealed the formation of mid-gap states in mixed-linker MOFs, causing the bandgap reduction. Interestingly, although both MOFs have similar composition, the effect is more significant in MIL-140A than in UiO-66. This is due to the presence of π-π stacking interactions in MIL-140A, which does not occur in UiO-66. The simulation results reveal a direct relationship between the strength of π-π interactions and the bandgap. This illustrates that distinct structural features, particularly the orientation of organic linkers can give rise to different consequences in bandgap modulation. Moreover, this computational work highlights the possibility to engineer the electronic properties of MOFs through a mixed-linker approach.The stability of supported metal nanoparticles determines the activity and lifetime of heterogeneous catalysts. Catalysts can destabilize through several thermodynamic and kinetic pathways, and the competition between these mechanisms complicates efforts to quantify and predict the overall evolution of supported nanoparticles in reactive environments. Pairing in situ transmission electron microscopy with unsupervised machine learning, we quantify the destabilization of hundreds of supported Au nanoparticles in real-time to develop a model describing the observed particle evolution as a competition between evaporation and surface diffusion. Data mining of particle evolution statistics allows us to determine physically reasonable values for the model parameters, quantify the particle size at which the Gibbs-Thomson pressure accelerates the evaporation process, and explore how individual particle interactions deviate from the mean-field model. This approach can be applied to a wide range of supported nanoparticle systems, allowing quantitative insight into the mechanisms that control their evolution in reactive environments.Heteroatom doping is a powerful strategy to alter the electronic structure of polycyclic aromatic hydrocarbons (PAHs). Especially boron doping endows PAH scaffolds with electron-accepting character and Lewis acidic centers. Herein, we report that embedding a five-membered borole ring into a polycyclic skeleton imparts the π-system with antiaromatic character and thereby induces unique properties and behavior. A series of borole-embedded π-conjugated compounds were synthesized from teraryl precursors via a borylation/intramolecular electrophilic C-H borylation sequence. The obtained compounds exhibit planar structures with distorted geometries around the boron center and form columnar slipped face-to-face π-stacked structures. Among these compounds, a pyrene-fused derivative shows an intense emission with a high quantum yield in solution. This compound also exhibits high Lewis acidity, which reflects the antiaromatic character and strained structure of the borole substructure. This compound forms a Lewis acid-base adduct even with weakly Lewis basic phosphorus-containing polycyclic π-systems. Analyzing the crystal structure of the thus-obtained adduct revealed a complex between the boron- and phosphorus-embedded π-systems with a direct B-P dative bond. This complex undergoes photodissociation in the excited state and exhibits an emission exclusively from the base-free borole-embedded π-system.All-solid-state lithium-metal batteries, with their high energy density and high-level safety, are promising next-generation energy storage devices. Selleck GSK046 Their current performance is however compromised by lithium dendrite formation. Although using 3D-structured metal-based electrode materials as hosts to store lithium metal has the potential to suppress the lithium dendrite growth by providing a high surface area with lithiophilic sites, their rigid and ragged interface with solid-state electrolytes is detrimental to the battery performance. Herein, we show that Li2OHBr-containing poly(ethylene oxide) (PEO) polymer electrolytes can be used as a flexible solid-state electrolyte to mitigate the interfacial issues of 3D-structured metal-based electrodes and suppress the lithium dendrite formation. The presence of Li2OHBr in a PEO matrix can simultaneously improve the mechanical strength and lithium ion conductivity of the polymer electrolyte. It is confirmed that Li2OHBr does not only induce the PEO transformation of a crystalline phase to an amorphous phase but also serves as an anti-perovskite superionic conductor providing additional lithium ion transport pathways and hence improves the lithium ion conductivity. The good interfacial contact and high lithium ion conductivity provide sufficient lithium deposition sites and uniform lithium ion flux to regulate the lithium deposition without the formation of lithium dendrites. Consequently, the Li2OHBr-containing PEO polymer electrolyte in a lithium-metal battery with a 3D-structured lithium/copper mesh composite anode is able to improve the cycle stability and rate performance. The results of this study provide the experimental proof of the beneficial effects of the Li2OHBr-containing PEO polymer electrolyte on the 3D-structured lithium metal anode.The benefit of enriching solid-electrolyte interface with fluorine atoms through the use of fluorinated additives into the electrolyte composition has recently gained popularity for anode materials used in secondary lithium-ion batteries. Another strategy is to provide these fluorine atoms via surface fluorination of the electrode material, particularly for multiwalled carbon nanotube (MWCNT)/SnO2-based composites where fluorination must act selectively on SnO2. Our study presents two methods of surface fluorination applied on MWCNT/SnO2, one using F2(g) and the other XeF2(s). These fluorinating agents are known for their different particle penetration depths. An ultrathin and very dense fluorinated layer achieved by the action of F2(g) allows to form a very stable interface leading to gravimetric capacities of 789 mA h g-1 after 50 cycles. A thin and porous fluorinated layer made by the action of XeF2(s) favors the formation of a new Sn-based fluorinated phase, never reported in the literature, which also stabilizes capacities over 50 cycles.