Publications by authors named "Sangeun Cho"

Using electrocatalytic water reduction to produce hydrogen fuel offers significant potential for clean energy, yet its large-scale adoption depends on developing cost-effective, non-precious, and efficient catalysts to replace expensive Pt-based state-of-the-art HER catalysts. The catalytic HER performance of an active catalyst largely depends on the available catalytic active sites, conductivity, and intrinsic electrochemical kinetics, all of which can be altered by incorporating a heteroatom into the active catalyst structure. Herein, we synthesized a unique nitrogen-doped CuO@CuS (NCOS) core-shell-structured catalyst through a facile hydrothermal process followed by an efficacious nitrogenation process, and its electrochemical performance for the HER was systematically analyzed.

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The deprived electrochemical kinetics of the oxygen evolution reaction (OER) catalyst is the prime bottleneck and remains the major obstacle in the water electrolysis processes. Herein, a facile hydrothermal technique was implemented to form a freestanding polyhedron-like CoO on the microporous architecture of Ni foam, its reaction kinetics enhanced through sulfide counterpart transformation in the presence of NaS, and their catalytic OER performances comparatively investigated in 1 M KOH medium. The formed CoS catalyst shows outstanding catalytic OER activity at a current density of 100 mA cm by achieving a relatively low overpotential of 292 mV compared to the pure CoO catalyst and the commercial IrO catalyst.

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Article Synopsis
  • The study addresses challenges in creating stable orange-emitting Mn-doped perovskite, focusing on uniformdopant distribution, structural integrity, and luminescent efficiency.
  • A novel one-step, water-induced synthesis method at room temperature allows for control over nanostructure shapes by adjusting water-based precursor amounts, leading to stable mixed-halide perovskites.
  • The resulting materials demonstrate remarkable stability, maintaining high photoluminescence under various conditions and achieving warm white light emission with a broad color range, suggesting potential for use in displays and lighting.
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Developing effective and long-lasting electrocatalysts for oxygen evolution reaction (OER) is critical for increasing sustainable hydrogen production. This paper describes the production and characterization of CoFeP nanoparticles (CFP NPs) as high-performance electrocatalysts for OER. The CFP NPs were produced using a simple hydrothermal technique followed by phosphorization, yielding an amorphous/crystalline composite structure with improved electrochemical characteristics.

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Niclosamide, a potent anthelmintic agent, has emerged as a candidate against COVID-19 in recent studies. Its formulation has been investigated extensively to address challenges related to systemic exposure. In this study, niclosamide was formulated as a long-acting intramuscular injection to achieve systemic exposure in the lungs for combating the virus.

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Intensive research on optoelectronic memory (OEM) devices based on two-dimensional (2D) van der Waals heterostructures (vdWhs) is being conducted due to their distinctive advantages for electrical-optical writing and multilevel storage. These features make OEM a promising candidate for the logic of reconfigurable operations. However, the realization of nonvolatile OEM with broadband absorption (from visible to infrared) and a high switching ratio remains challenging.

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Water electrolysis is a highly efficient route to produce ideally clean H fuel with excellent energy conversion efficiency and high gravimetric energy density, without producing carbon traces, unlike steam methane reforming, and it resolves the issues of environmental contamination via replacing the conventional fossil fuel. Particular importance lies in the advancement of highly effective non-precious catalysts for the oxygen evolution reaction (OER). The electrocatalytic activity of an active catalyst mainly depends on the material conductivity, accessible catalytically active sites, and intrinsic OER reaction kinetics, which can be tuned via introducing N heteroatoms in the catalyst structure.

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Ligand-assisted re-precipitation (LARP) is one of the most practicing techniques for synthesizing colloidal nanocrystals (NCs). But due to its fast reaction kinetics, it offers limited synthesis control. In the present study, we report a novel, precursor silanization-based room temperature technique unveiling slow crystallization of CsPbBr/CsPbBr dual-phase nanocrystals (DPNCs) protected with a dense silica cloud-like matrix.

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Green hydrogen derived from the water-electrolysis route is emerging as a game changer for achieving global carbon neutrality. Economically producing hydrogen through water electrolysis, however, requires the development of low-cost and highly efficient electrocatalysts scalable synthetic strategies. Herein, this work reports a simple and scalable immersion synthetic strategy to deposit reduced graphene oxide (rGO) nanosheets integrated with Ni-Fe-based hydroxide nanocatalysts on nickel foam (NF) at room temperature.

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The oxygen evolution reaction (OER) plays a key role in determining the performance of overall water splitting, while a core technological consideration is the development of cost-effective, efficient, and durable catalysts. Here, we demonstrate a robust reduced Fe-oxide@NiCoO bilayered non-precious-metal oxide composite as a highly efficient OER catalyst in an alkaline medium. A bilayered oxide composite film with an interconnected nanoflake morphology (FeO@NiCoO) is reduced in an aqueous NaBH solution, which results in a mosslike FeO@NiCoO (reduced Fe-oxide@NiCoO; rFNCO) nanostructured film with an enhanced electrochemical surface area.

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Radionuclide Sr in aqueous solution was removed using a large amount of banana peel (BP). Magnetized BP, mag@BP, was synthesized for recovery after the adsorption process. The synthesis was a very simple process of precipitation of BP with a magnetic substance.

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Compared with solid scintillators, liquid scintillators have limited capability in dosimetry and radiography due to their relatively low light yields. Here, we report a new generation of highly efficient and low-cost liquid scintillators constructed by surface hybridisation of colloidal metal halide perovskite CsPbA (A: Cl, Br, I) nanocrystals (NCs) with organic molecules (2,5-diphenyloxazole). The hybrid liquid scintillators, compared to state-of-the-art CsI and GdOS, demonstrate markedly highly competitive radioluminescence quantum yields under X-ray irradiation typically employed in diagnosis and treatment.

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The oxygen-evolution reaction (OER) is critical in electrochemical water splitting and requires an efficient, sustainable, and cheap catalyst for successful practical applications. A common development strategy for OER catalysts is to search for facile routes for the synthesis of new catalytic materials with optimized chemical compositions and structures. Here, nickel hydroxide Ni(OH) 2D nanosheets pillared with 0D polyoxovanadate (POV) nanoclusters as an OER catalyst that can operate in alkaline media are reported.

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CuCo O films with different morphologies of either mesoporous nanosheets, cubic, compact-granular, or agglomerated embossing structures are fabricated via a hydrothermal growth technique using various solvents, and their bifunctional activities, electrochemical energy storage and oxygen evolution reaction (OER) for water splitting catalysis in strong alkaline KOH media, are investigated. It is observed that the solvents play an important role in setting the surface morphology and size of the crystallites by controlling nucleation and growth rate. An optimized mesoporous CuCo O nanosheet electrode shows a high specific capacitance of 1658 F g at 1 A g with excellent restoring capability of ≈99% at 2 A g and superior energy density of 132.

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A mesoporous nanoplate network of two-dimensional (2D) layered nickel hydroxide Ni(OH)2 intercalated with polyoxovanadate anions (Ni(OH)2-POV) was built using a chemical solution deposition method. This approach will provide high flexibility for controlling the chemical composition and the pore structure of the resulting Ni(OH)2-POV nanohybrids. The layer-by-layer ordered growth of the Ni(OH)2-POV is demonstrated by powder X-ray diffraction and cross-sectional high-resolution transmission electron microscopy.

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This study evaluated frequency-dependent effects of extremely low frequency electromagnetic fields (ELF-EMFs) on melanogenesis by melanocytes in vitro. Melanocytes were exposed to 2 mT EMFs at 30-75 Hz for 3 days before melanogenesis was examined. Exposure to ELF-EMFs at 50 and 60 Hz induced melanogenic maturation without cell damage, without changing cell proliferation and mitochondrial activity.

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The dataset presented here is related to the research article entitled "Highly Efficient Electro-optically Tunable Smart-supercapacitors Using an Oxygen-excess Nanograin Tungsten Oxide Thin Film" (Akbar et al., 2017) [9] where we have presented a nanograin WO film as a bifunctional electrode for smart supercapacitor devices. In this article we provide additional information concerning nanograin tungsten oxide thin films such as atomic force microscopy, Raman spectroscopy, and X-ray diffraction spectroscopy.

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Aims: This study's purpose was to evaluate the effect of ultrasound in air at a frequency of 0.04MHz and an intensity of 50mW/cm on neural differentiation of hBM-MSCs in vitro and on neurogenesis in an ischemic stroke model.

Materials And Methods: hBM-MSCs were exposed to 0.

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Melanogenesis is the biological process that results in the synthesis of skin pigment of melanin and it has various functions in living systems and is synthesized by the melanosome within the melanocytes. A variety of physical treatments are used to promote melanin production in the melanocytes for pigmentation control. The purpose of this study was to evaluate the intensity-dependent effect of extremely low-frequency electromagnetic fields (ELF-EMFs) on melanogenesis by melanocytes .

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Melanin in the skin determines the skin color, and decreased melanin causes many hypopigmentation disorders and increased damage to skin by ultraviolet B (UVB) light irradiation. Here, we stimulate melanogenesis in B16F10 melanoma cells by using specific frequencies of ELF-EMFs. In this study, we focus on the melanogenesis of EMF-ELFs and find that 60-75Hz ELF-EMFs upregulate melanin synthesis by stimulated expression of tyrosinase and TRP-1 through inhibition of phosphorylation ERK, activation of CREB, and MITF up-regulation in B16F10 melanoma cells.

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We investigate the resistive switching power from unipolar resistive switching current-voltage characteristics in various binary metal oxide films sandwiched by different metal electrodes, and find a universal feature (the so-called universality) in the switching power among these devices. To experimentally derive the switching power universality, systematic measurements of the switching voltage and current are performed, and neither of these correlate with one another. As the switching resistance (R) increases, the switching power (P) decreases following a power law P ∝ R(-β), regardless of the device configurations.

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This study investigates the transport and switching time of nonvolatile tungsten oxide based resistive-switching (RS) memory devices. These devices consist of a highly resistive tungsten oxide film sandwiched between metal electrodes, and their RS characteristics are bipolar in the counterclockwise direction. The switching voltage, retention, endurance, and switching time are strongly dependent on the type of electrodes used, and we also find quantitative and qualitative evidence that the electronegativity (χ) of the electrodes plays a key role in determining the RS properties and switching time.

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This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate.

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