Heterogeneous Nucleation Growth Research Articles

Tuning Molten-Salt-Mediated Calcination in Promoting Single-Crystal Synthesis of Ni-Rich LiNixMnyCozO2 Cathode Materials

High Ni-content LiNixMnyCozO2 (NMC) cathodes (with x ≥ 0.8, x + y + z = 1) have gained attention recently for their high energy density in electric vehicle (EV) Li-ion batteries. However, Ni-rich cathodes pose challenges in capacity retention due to inherent structural and surface redox instabilities. One promising strategy is to make the Ni-rich NMC material in the form of single-crystal micron-sized particles, as they resist intergranular and surface degradation during cycling. Among various methods to synthesize single-crystal NMC (SC-NMC) particles, molten-salt-assisted calcination offers distinct processing advantages but at present, is not yet optimized or mechanistically clarified to yield the desired control over crystal growth and morphology. In this project, molten-salt-mediated transformation of Ni0.85Mn0.05Co0.15(OH)2 precursor (P-NMC) particles to LiNi0.85Mn0.05Co0.15O2 particles is investigated in terms of the crystal growth mechanism and its electrochemical response. Unlike previous studies that involved large volumes of molten salt, using a smaller volume of molten KCl is found to result in larger primary particles with improved cycling performance achieved via partial reactive dissolution and heterogeneous nucleation growth, suggesting that the ratio of molten salt volume to NMC mass is an important parameter in the synthesis of single-crystal Ni-rich NMC materials.

Versatile hollow COF nanospheres via manipulating transferrin corona for precise glioma-targeted drug delivery

Covalent organic framework (COF) nanoparticles for interference-free targeted drug delivery to glioma remains in its infancy. Herein, hollow COF nanospheres with high crystallinity and uniformed sizes were facilely prepared via heterogeneous nucleation-growth. The prepared COF had large surface area/pore volume and exhibited appropriate degradation behavior under acid environment, where therefore doxorubicin was effectively encapsulated and exhibited a pH-sensitive release. Most charmingly, T10 peptide that has high affinity with transferrin (Tf), was conjugated to endow the hollow COF interesting properties to specifically absorb Tf in vivo as Tf corona. For the first time, multifunctional hollow COF nanospheres (the better one named DCPT-2) were successfully synthesized to achieve interference-free cascade-targeting glioma drug delivery across the blood-brain barrier. Treatment with DCPT-2 brought an improved therapeutic outcome with significantly prolonged median survival time and low side effects. This work promised not only a potential protein corona-mediated COF-based drug delivery platform with good biocompatibility for effective and precise brain tumor therapy, but also an endogenous protein corona-mediated targeting strategy for general cancer therapy.

Tin-Incorporation Induced Changes in the Microstructural, Optical, and Electrical Behavior of Tungsten Oxide Nanocrystalline Thin Films Grown Via Spray Pyrolysis

Undoped and Sn-doped WO3 thin films were grown on cleaned glass substrates by chemical spray pyrolysis, using ammonium tungstate (NH4)(2)WO4 as the host precursor and tin chloride (SnCl4 center dot 5H(2)O) as the source of dopant. The XRD spectra confirm the monoclinic structure with a sharp narrow peak along (200) direction along with other peaks of low relative intensities for all the samples. On Sn doping, the films exhibit reduced crystallinity relative to the undoped film. The standard deviation for relative peak intensity with dopant concentration shows enhancement in heterogeneous nucleation growth. As evident from SEM images, on Sn doping, appearance of island-like structure (i.e., cluster of primary crystallites at few places) takes place. The transmittance has been found to decrease in all the Sn-doped films. The optical band gap has been calculated for both direct and indirect transitions. On Sn doping, the direct band gap shows a red shift and becomes 2.89 eV at 2 at.% doping. Two distinct peaks, one blue emission at 408 nm and other green emission at 533 nm, have been found in the PL spectra. Electrical conductivity has been found to increase with Sn doping.