Transition metal oxides are considered alternative electrocatalysts for ZAB owing to their multiple oxidation states. However, they have limitations such as low electrical conductivity and the deficiency of reactive sites. In this study, to overcome these shortcomings and improve electrocatalytic activity, oxygen vacancies and porous architectures were introduced through a partial reduction process and a porous carbon framework. Open porous carbon microspheres with uniformly loaded NiCo₂O₄ nanosheets and oxygen vacancies (V‐NCO/OPC) displayed enhanced electrocatalytic performance with a low Tafel slope (68 mV dec^-1) in the oxygen reduction reaction (ORR) and a low overpotential (402 mV) at 10 mA cm^–2 in the oxygen evolution reaction (OER). The combined effect of the oxygen vacancies and porous architecture can offer sufficient active sites, modify the electronic structure of the metal oxide surface, and facilitate mass transport, enhancing the electrocatalytic properties of V‐NCO/OPC. Furthermore, when applied for ZAB, V‐NCO/OPC demonstrated better electrochemical performance including discharge power density (154.9 mW cm^-2) at the current density of 175.9 mA cm^-2, low voltage gap (0.85 V) at the initial cycle, and long‐term (250 h) cycle stability at the current density of 10 mA cm⁻² than those of noble‐metal electrocatalysts.

This study compares the characteristics and low-temperature curing properties of pastes prepared from silver (Ag) powders synthesized by either wet powder (WP) or dry powder (DP) processing. The WP synthesis of electrode particles has the advantage of controlling the average particle size and particle size distribution but the disadvantage of producing low-purity, crystalline particles because they are synthesized through chemical reduction at less than 100 °C. Conversely, the DP synthesis of electrode particles has the advantage of producing pure, highly crystalline particles (due to synthesis at high temperatures) but the disadvantage of a high processing cost. WP and DP were used to manufacture pastes for low-temperature curing, and the physical properties of the pastes and the electrode characteristics after low-temperature curing were compared between powder types. Shear stress as a function of the shear rate shows that the WP paste is a plastic fluid, whereas the DP paste is a pseudoplastic fluid, closer to a Newtonian fluid. Screen printing the Ag pastes and curing for 30 min at 130 °C produces a nonconductive WP paste, whereas it produces a DP paste with a conductivity of 61 mΩ/sq, indicating that the highly crystalline DP paste is advantageous for low-temperature curing.

Lithium metal anodes (LMAs) have attracted significant attention owing to their high theoretical capacity and lowest redox potential. However, dendritic growth of lithium limits its practical application. Controlling lithium deposition through structuring host materials for LMAs has been widely studied. In this study, a unique structured CuO-Cu₂O-Cu composite microsphere is synthesized through facile one-step spray pyrolysis process as a new lithium host material for LMAs. During lithium deposition, lithium ions preferred to be adsorbed on composite microspheres due to the electric field generated from the metallic Cu-based conductive matrix. The adsorbed ions reacted with lithiophilic copper oxides to form copper and Li₂O, promoting the generation of a uniform electric field and ion transfer. Moreover, hollow structure can guide lithium to be encapsulated inside the structures, enabling effective suppression of dendritic lithium growth. As a result, this composite microsphere is capable to store lithium with high areal capacity of 5.0mAhcm^-2 without dendritic growth of lithium. Consequently, the composite microspheres exhibit a coulombic efficiency above 99 for more than 200 cycles at a current density of 1.0mAcm^-2 as an asymmetric cell and show low voltage hysteresis of 19mV for more than 1,000h as a symmetric cell. This study demonstrates that the designed microstructures with an appropriate ratio of conductive and lithiophilic matrices with sufficient pore structures provide promising cycle performance as host materials for lithium metal anode.

The efficient hydrogenation of 1-butene is an industrially significant reaction for producing fuels and value-added chemicals. However, achieving high catalytic efficiency and stability remains challenging, particularly for cost-effective materials, such as Ni. In this study, we developed a porous Ni-coated Ni foam catalyst by electrostatic spray deposition to address these challenges. The catalyst exhibited a turnover frequency approximately 10 times higher than that of either porous Ni or Ni foam alone. This enhancement was attributed to the formation of interfacial active sites, which facilitated improved reactant adsorption and activation during hydrogenation. The electrostatic spray deposition technique ensured a uniform and controlled coating, enabling precise engineering of the catalyst structure and interface. The post-deposition heat treatment was further optimized to enhance structural integrity and catalytic performance. This study highlights the importance of interface engineering and structural optimization in catalyst design and provides valuable insights into the development of efficient Ni-based catalysts for industrial hydrogenation applications. These findings emphasize the potential of electrostatic spray deposition as a versatile method for fabricating advanced catalytic systems.

The Bi–Te thermoelectric system shows an excellent figure of merit (ZT) near room temperature. Research on increasing the ZT value for n‑type Bi–Te is imperative because the thermoelectric properties of this compound are inferior to those of the p-type material. For this purpose, n-type Bi₂Te_3-ySe_y powders with various amounts of Se dopant (0.3 ≤ y ≤ 0.6) were synthesized by a vacuum melting-grinding process to improve the physical properties. The ZT value of the sintered bodies was investigated in the temperature range of 298–423 K with regard to the electrical and thermal characteristics. As the Se content increased, the electrical conductivity decreased owing to a reduction in the carrier concentration, which improved the overall value of ZT. The thermal conductivity clearly decreased as the Se content increased in the temperature range of 298–373 K due to increased alloy scattering, as well as a reduction in the lattice thermal conductivity caused by crystal grain boundary scattering. At room temperature, Bi₂Te_2.7Se_0.3 (y = 0.3) exhibited the highest ZT of 0.85. At increased temperatures, the ZT value was highest for Bi₂Te_2.55Se_0.45 (y = 0.45), indicating that the optimal effect of the Se dopants varies depending on the temperature range.