A pathway of nanocrystallite fabrication by photo-assisted growth in pure water

Abstract

We report a new production pathway for a variety of metal oxide nanocrystallites via submerged illumination in water: submerged photosynthesis of crystallites (SPSC). Similar to the growth of green plants by photosynthesis, nanocrystallites shaped as nanoflowers and nanorods are hereby shown to grow at the protruded surfaces via illumination in pure, neutral water. The process is photocatalytic, accompanied with hydroxyl radical generation via water splitting; hydrogen gas is generated in some cases, which indicates potential for application in green technologies. Together with the aid of ab initio calculation, it turns out that the nanobumped surface, as well as aqueous ambience and illumination are essential for the SPSC method. Therefore, SPSC is a surfactant-free, low-temperature technique for metal oxide nanocrystallites fabrication.

In situ direct observation of photocorrosion in ZnO crystals in ionic liquid using a laser-equipped high-voltage electron microscope

“…The incident light-excited electrons then generated holes near the surface. As noted by Jeem et al, 19 when there is water near the surface, holes react with H 2 O molecules to make OH radicals and H + ions. Jeem et al 19 proposed the following whole chemical reactions:…”

“…Recently, Jeem et al discovered a way to produce metal-oxide nanocrystals in ultrapure water via submerged photosynthesis of crystallites (SPSC), 19,20 which built wurtzite ZnO nanorods from Zn 2+ ions dissolved in water and from O 2-ions produced by the photocatalytic effect of H 2 O under UV irradiation. This synthesis process requires no additives, unlike other methods.…”

“…To confirm the effect of irradiation, we studied crystalline ZnO nanorods grown in water under UV irradiation. 19,20 These crystals are known to be self-corrosive under submerged illumination. Rather than water, we used ionic liquid for a safe fluid environment.…”

“…2(a), the plasma-treated Zn surface had ZnO nanobumps with a typical diameter of 10-20 nm, which later acted as nucleation centers for ZnO nanorods. 19 The Zn substrate in ultrapure water was irradiated ex situ using a UV lamp (UVP, B-100AP, USA) with 100-W long-wave UV (λ = 365 nm, 3.4 eV). After irradiation for 72 h, the crystal growth toward the c-axis had almost completed, and many ZnO nanocrystals had formed nanoflowers ( Fig.…”

Formation of CuO nano-flowered surfaces via submerged photo-synthesis of crystallites and their antimicrobial activity

“…In the pure water environment, the photochemical reaction is considered to contribute to the ZnO nanorod fabrication, as indicated following reaction: . In addition, it was suggested that the formation of the ZnO nanoflowers by SPSC was accompanied by a photoradical reaction via water decomposition, and it was also confirmed that hydrogen is generated during the reaction 19 .…”