Here, we report on a one-pot mechanochemical ball milling synthesis of manganese oxide nanostructures synthesized at different milling speeds for efficient carbon dioxide reduction catalyst.

No abstract

The ongoing search for new photoelectrode materials generated interest toward semiconductors containing multiple anions. In this work, three different antimony oxide iodides (Sb 3 O 4 I, Sb 8 O 11 I 2 , and Sb 5 O 7 I) were synthesized by anhydrous synthesis. Scanning electron microscopy revealed mainly needle-shaped particles for Sb 3 O 4 I, elongated plate-shaped ones for Sb 8 O 11 I 2 and wellcrystallized hexagonal particles for Sb 5 O 7 I. The isoelectric point of the antimony oxide iodides (pH∼3) was independent of the chemical composition. With increasing pH particles became negatively charged to different extents, depending on the relative amount of oxygen in the samples, through the presence of ≡Sb−O − surface functional groups. The optical properties were heavily affected by the composition as well: bandgap energies related to the direct transitions in Sb 3 O 4 I, Sb 8 O 11 I 2 , and Sb 5 O 7 I were 2.16 and 2.74 eV, 2.85 eV, and 3.25 eV, respectively. Photoelectrochemical analysis proved that all samples behave as n-type semiconductors, but the performance in water oxidation showed large variation for the different compositions. The band energy diagram was constructed for all compounds and the composition dependent optoelectronic properties were rationalized on this basis.

Doctoral (Ph.D.) dissertationOchirkhuyag Altantuya iii 4.4.1The catalyst for oxygen reduction reaction (ORR) .

In developed countries, nanoparticles derived from natural minerals and high-purity chemicals both are widely studied, while in developing countries like Mongolia, the natural minerals-based nanoparticles have more interest because of the low production cost and applicability of domestic natural minerals for their production. For the synthesis of natural mineral-based nanomaterials, it is important first to define the chemical composition and physical structure of local minerals and their possible processing route. We employed an environmentally friendly alkaline leaching procedure to recover silica from the clay mineral at 90°C for 24 hours. We applied an organic surfactant (CTAB) and a simple coprecipitation approach to form iron-doped silica nanoparticles. Consequently, we used iron-doped silica nanoparticles as a substrate and catalyst for the synthesis of carbon nanosphere at 750 °C for 1 hour in an argon and acetylene gas atmosphere. As a result, vast quantities of superhydrophobic carbon nanospheres (CNS) were obtained. The physicochemical properties of nanosilica substrate, non-functionalized carbon nanosphere, and functionalized carbon nanosphere (CNS) samples were characterized using XRD, XRF, SEM, EDS, TEM, and FTIR spectrometer. Iron-doped mineral-derived nanosilica particles demonstrated high catalytic efficiency and the potential to produce a large amount of value-added carbon nanospheres. Superhydrophobic CNS can be used in a variety of applications, particularly drug delivery; however, to use CNS in both aqueous and non-aqueous media, the superhydrophobic properties of CNS can be modified using different oxidizers. The changes in hydrophobicity of the CNS were examined and suggested possible oxidizing agents.