한형수

Barium titanate (BT) ceramics with Ba/Ti ratios of 0.95 and 1.00 were synthesized using spark plasma sintering (SPS) technique. Dielectric spectroscopy (frequency range from 40 Hz to 1 MHz and temperature range from 300 K to 30 K) was performed on those ceramics (SPS BT). SPS BT showed extremely high permittivity up to ∼105, which can be referred to as colossal permittivity, with relatively low dielectric loss of ∼0.05. Data analyses following Debye relaxation and universal dielectric response m

Abstract Generation of hydrogen fuel via electrochemical water splitting powered by sustainable energy, such as wind or solar energy, is an attractive path toward the future renewable energy landscape. However, current water electrolysis requires desalinated water resources, eventually leading to energy costs and water scarcity. The development of cost‐effective electrocatalysts capable of splitting saline water feeds directly can be an evident solution. Herein, a surface reconstructed nickel‐ir

Fast-fired barium titanate ceramics have been shown to exhibit room temperature colossal permittivity (εr′ ≈ 105, tan δ ≈ 0.05 at 1 kHz) when synthesized via the spark plasma sintering technique. Broadband dielectric spectroscopy analysis is here utilized to identify the active conduction mechanisms in the compound. Analysis of the temperature-dependent bulk dc conductivity reveals that the bulk conduction in fast-fired barium titanate is the result of variable-range hopping with relatively shor

Undoped and Sb-doped BiI3 (SBI) single crystals are grown via the vertical Bridgman growth technique. Electrical properties, such as resistivity and leakage current, in addition to radiation response measurements are performed on both BiI3 and SBI single crystal detectors. The resistivity of SBI (2.63109 Ω·cm) increases by an order of magnitude compared to that of BiI3 (1.45 × 108 Ω·cm). Furthermore, leakage currents of SBI (10–2 μA/cm2) decrease by four orders magnitude relative to BiI3. The ra

The proton exchange membrane water electrolysis (PEMWE) powered by renewable electricity offers a facile route for clean hydrogen production. The oxygen evolution reaction (OER) at the anode plays a major role in affecting the overall device efficiency due to its sluggish OER kinetics. Thus, it remains a challenge to develop robust and active catalysts for OER in acid media for efficient PEMWE. Currently, iridium (Ir)-based materials, such as mono- and multimetallic Ir, Ir-based oxides, pyrochlo

Abstract The development of earth‐abundant and efficient oxygen evolution reaction (OER) electrocatalysts is necessary for green hydrogen production. The preparation of efficient OER electrocatalysts requires both the adsorption sites and charge transfer on the catalyst surface to be suitably engineered. Herein, the design of an electrocatalyst is reported with significantly enhanced water oxidation performance via dual‐phase engineering, which displays a high number of adsorption sites and faci

Transition metal (TM)-based carbon hybrids have numerous applications in the field of regenerative electrochemical energy. The synergetic effects of high conductivity of carbon supports and abundant catalytic active sites in TMs make these hybrids promising oxygen evolution reaction (OER) electrocatalysts. However, strategies for modulating the catalytic active species in the above hybrids are limited despite being highly sought after. Furthermore, the exact roles of chemical species in the hybr

Nb and In co-doped rutile TiO2 nanoceramics (n-NITO) were successfully synthesized through a chemical-solution route combined with a low temperature spark plasma sintering (SPS) technique. The particle morphology and the microstructure of n-NITO compounds were nanometric in size. Various techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG)/differential thermal analysis (DTA), Fourier transform infrared (FTIR), and Raman spectroscopy were used

Quaternary multimetallic LDHs have been developed through a facile metal–organic-framework derived electrochemical activation process. Ni–Fe–Al–Co quaternary LDHs show one of the best OER performances in alkaline and seawater electrolytes.

Colossal permittivity (ε′ = 301,484 at room temperature and 1 kHz) of barium titanate was induced in ceramics synthesized using the microwave sintering method. Three different sintering processes (conventional, spark plasma, and microwave) were performed to better understand colossal permittivity in sintered barium titanate. The dielectric permittivity measurements revealed that the appearance of colossal permittivity has strong dependence on the sintering temperature and atmosphere, and less on