Phase Transformation of Colloidal In2O3 Nanocrystals Driven by the Interface Nucleation Mechanism: A Kinetic Study

Decorating of 2D indium oxide onto 2D bismuth oxybromide to enhance internal electric field and stimulate artificial photosynthesis

CO2 photocatalytic reduction is an excellent strategy for promoting solar-to-chemical energy conversion and alleviating the severe environmental crisis. In this study, 2D indium oxide (IO) is decorated on 2D bismuth oxybromide (BOB) nanosheets to gain BOB/IO (BxIy) heterojunction. The optimal B3I1 composite affords a CO production rate of 54.2 μmol⋅g-1, about 2.2 times and 11.3 times higher than those of the pristine BOB and IO, respectively. The introduction of IO significantly enhances the internal electric field (IEF), leading to accelerated charge transfer and prolonged lifetime of the photogenerated carriers. In the BxIy composite, the BOB and IO serve as the electron acceptor and donor, respectively, facilitating the reduction of CO2 and oxidation of H2O. In-situ DRIFTs spectra are used to confirm the catalytic active sites and provide insights into the mechanism of CO2 photoreduction. The results suggest *COOH and *CO2- species played a crucial role in the formation of CO. This work presents a valuable perspective on understanding the charge transfer route and developing highly efficient photocatalysts for CO2 photoreduction.

Defects and impurities in colloidal Ga2O3 nanocrystals: new opportunities for photonics and lighting

Defects, both native and extrinsic, critically determine functional properties of metal oxides. Gallium oxide has recently gained significant attention for its promise in microelectronics, owing to the unique combination of conductivity and high breakdown voltage, and solid-state lighting, owing to the strong photoluminescence in the visible spectral region. These properties are associated with the presence of native defects that can form both donor and acceptor states in Ga2O3. Recently, Ga2O3 nanocrystal synthesis in solution and optical glasses has been developed, allowing for a range of new applications in photonics, lighting, and photocatalysis. This review focuses on the structure and properties of Ga2O3 nanocrystals with a particular emphasis on the electronic structure and interaction of defects in reduced dimensions and their role in the observed photoluminescence properties. In addition to native defects, the effect of selected external impurities, including lanthanide and aliovalent dopants, and alloying on the emission properties of Ga2O3 nanocrystals are also discussed.

A Polyol-Mediated Fluoride Ions Slow-Releasing Strategy for the Phase-Controlled Synthesis of Photofunctional Mesocrystals

There are only a few inorganic compounds that have evoked as much interest as sodium yttrium fluoride (NaYF₄). Its extensive applications in various fields, including transparent displays, luminescence coding, data storage, as well as biological imaging, demand the precise tuning of the crystal phase. Controlling the emergence of the desired α-phase has so far remained a formidable challenge, especially via a simple procedure. Herein, we represented a polyol-assisted fluoride ions slow-release strategy for the rational control of pure cubic phase NaYF₄ mesocrystals. The combination of fluorine-containing ionic liquid as a fluoride source and the existence of a polyalcohol as the reactive medium ensure the formation of uniform α-phase mesocrystallines in spite of a higher temperature and/or higher doping level.

Native defects determine phase-dependent photoluminescence behavior of Eu(2+) and Eu(3+) in In2O3 nanocrystals

We demonstrate the coexistence of Eu(2+) and Eu(3+) in corundum and bixbyite-type colloidal In2O3 nanocrystals. The emission properties of dopants in both oxidation states are determined by their interaction with native defects, and are dramatically different in the two nanocrystal phases. This difference arises from the smaller nanocrystal size and higher defect density in metastable corundum-type nanocrystals.

Corundum type indium oxide nanostructures: ambient pressure synthesis from InOOH, and optical and photocatalytic properties

A simple, cost effective, surfactant free and scalable synthesis of rh-In₂O₃ nanostructures showing intense blue light emission has been developed under ambient pressure.

Diffusion-driven and size-dependent phase changes of gallium oxide nanocrystals in a glassy host

Phase transformations at the nanoscale represent a challenging field of research, mainly in the case of nanocrystals (NCs) in a solid host, with size-effects and interactions with the matrix. Here we report the study of the structural evolution of γ-Ga2O3 NCs in alkali-germanosilicate glass - a technologically relevant system for its light emission and UV-to-visible conversion - showing an evolution drastically different from the expected transformation of γ-Ga2O3 into β-Ga2O3. Differential scanning calorimetry registers an irreversible endothermic process at ∼1300 K, well above the exothermic peak of γ-Ga2O3 nano-crystallization (∼960 K) and below the melting temperature (∼1620 K). Transmission electron microscopy and X-ray diffraction data clarify that glass-embedded γ-Ga2O3 NCs transform into LiGa5O8via diffusion-driven kinetics of Li incorporation into NCs. At the endothermic peak, β-Ga2O3 forms from LiGa5O8 dissociation, following a nucleation-limited kinetics promoted by size-dependent order-disorder change between LiGa5O8 polymorphs. As a result of the changes, modifications of UV-excited NC light emission are registered, with potential interest for applications.

Porous corundum-type In2O3 nanoflowers: controllable synthesis, enhanced ethanol-sensing properties and response mechanism

Porous rhombohedral In₂O₃ (corundum-type In₂O₃, rh-In₂O₃) with a morphology of uniform nanoflowers was fabricated by using a mild, facile solvent-thermal method.