Publications by authors named "Melbert Jeem"

Article Synopsis
  • - Intercalation reactions depend on how the electronic and structural properties of host (like TaS) and guest materials (like divalent ions) interact, making it harder for divalent ions like Mg to intercalate compared to monovalent ions.
  • - This study explores the cointercalation of Mg and hydrogen (H) into TaS to produce bulk polycrystalline MgHTaS, where hydrogen can be removed by heating at around 400 °C without changing the crystal structure.
  • - The research also investigates how the superconducting properties relate to electronic carrier density using both theoretical calculations and experiments, highlighting the benefits of using hydrides for intercalation reactions.
View Article and Find Full Text PDF

This study introduces a one-pot, submerged photosynthesis of crystallites (SPsC) method for fabricating monohydrate tungstic acid (WO·HO) nanoplates directly integrated onto a stainless steel mesh, offering a simplified production and enhanced device stability for optical functional applications. The fabricated devices demonstrate exceptional broadband light absorption across the ultraviolet (UV), visible (Vis), and near-infrared (NIR) ranges. Notably, 1% Cu doping significantly boosts the NIR absorption, yielding a high solar utilization efficiency of 81.

View Article and Find Full Text PDF

Not all encapsulation techniques are universally apt for every type of phase change material (PCM), highlighting the imperative for methodological precision. This study addresses the challenges of microencapsulated PCM (MEPCM) arising from the immiscible pairing of α-AlO nanoparticles with Sn microparticles. The high-speed impact blending (HIB) dry synthesis technique is employed, facilitating large-volume production of Sn@α-AlO MEPCMs.

View Article and Find Full Text PDF

Materials imbued with uniformly dispersed, photo-responsive nanoparticles are instrumental in sustainable energy and photonic applications. Conventional methods, however, constrain their all-solar response. An innovative alternative is proposed: submerged photo-synthesis of crystallites (SPsC).

View Article and Find Full Text PDF

A synthetic protocol was developed for obtaining a single phase of polycrystalline NaAlB with strongly connected intergrain boundaries. NaAlB has a unique crystal structure with a tunnel-like covalent framework of B that traps monovalent Na and trivalent Al ions. Owing to the atmospheric instability and volatility of Na, the synthesis of polycrystalline NaAlB and its physical properties have not been reported yet.

View Article and Find Full Text PDF

Recently, metal oxide nanocrystallites have been synthesized through a new pathway, i.e., the submerged photosynthesis of crystallites (SPSC), and flower-like ZnO nanostructures have been successfully fabricated via this method.

View Article and Find Full Text PDF

We report the fabrication of flower-like CuO nanostructured surfaces via submerged photo-synthesis of crystallites (SPSC), which requires only UV illumination in neutral water. In this paper, we discuss the reaction mechanism of the photochemical formation of the SPSC-fabricated CuO nanostructures in detail based on surface microstructural analyses and a radiation-chemical consideration with additional gamma-ray irradiation. Since the SPSC method for surface nanostructural fabrication can work at low temperatures at atmospheric pressure without using harmful substances, it is a potential fabrication method for green nanotechnology applications.

View Article and Find Full Text PDF

When applied in optoelectronic devices, a ZnO semiconductor dominantly absorbs or emits ultraviolet light because of its direct electron transition through a wide energy bandgap. On the contrary, crystal defects and nanostructure morphology are the chief key factors for indirect, interband transitions of ZnO optoelectronic devices in the visible light range. By ultraviolet illumination in ultrapure water, we demonstrate here a conceptually unique approach to tune the shape of ZnO nanorods from tapered to capped-end via apical surface morphology control.

View Article and Find Full Text PDF

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.

View Article and Find Full Text PDF