Ōtani University (大谷大学, Ōtani Daigaku) is a private Buddhist university in Kita-ku, Kyoto, Japan. Ōtani University is a coeducation institution with an emphasis on Buddhist studies. A two-year private junior college is associated with the university. The university is associated with the Ōtani School of Jōdo Shinshū, or Shin, school of Buddhism.
Achieving carbon neutrality requires not only cutting CO₂ emissions but also converting captured CO₂ into useful functions. This work tests whether carbonate ions produced by chemical-absorption direct air capture in alkaline media can act as charge carriers for electrochemical energy storage. Layered double hydroxides (LDHs) served as hosts for CO₃²⁻, and the influence of the metal-cation combination on carbonate intercalation and deintercalation was examined systematically. In a model electrolyte of 1 mol kg⁻¹ K₂CO₃, cyclic voltammetry showed no faradaic response for MgAl-LDH, while MnAl- and NiAl-LDH exhibited anion-coupled redox features. For NiAl-LDH the relevant couples lie outside the stability window of this electrolyte and therefore were not accessed. Comparisons with HCO₃⁻ and OH⁻ indicate that CO₃²⁻ is the predominant intercalating species. Galvanostatic charge and discharge measurements on a structurally optimized MnAl-LDH with abundant anion storage sites delivered initial capacities of 288 and 248 mAh g⁻¹, respectively. X-ray diffraction and X-ray photoelectron spectroscopy verified reversible expansion and contraction of the interlayer spacing together with a Mn³⁺ / ²⁺ redox process during carbonate intercalation and deintercalation. Although the capacity declined to 90 mAh g⁻¹ by cycle 20, composition tuning and morphology control are plausible routes to mitigate this loss. Electrochemical impedance spectroscopy indicated similar activation energies for insertion of CO₃²⁻ and OH⁻. The ability to trigger CO₃²⁻ release electrochemically, despite the strong stabilization of carbonate within LDH interlayers and its limited exchange under open-circuit conditions, points to electrochemically driven ion-exchange applications, including removal of hazardous anions.
We previously considered the effect of the energy dissipation term in time-dependent current-density-functional theory (ed-tdCDFT). Here, we expand the ed-tdCDFT by using energy bands composed of magnetic Bloch states. To derive the electric conductance tensor representing the conductivity parallel and perpendicular to the applied electric field, we apply perturbation theory up to the second order to the Kohn-Sham equation of the present ed-tdCDFT. The nondiagonal part of the electric conductance tensor consists of two terms, with the first term providing the integer quantum Hall effect (IQHE). The second term of the nondiagonal part corresponds to the Hall effect (HE). The diagonal part provides a quantum-mechanical expression of Ohm's conductivity. It is shown that the second term of the nondiagonal part is reduced to the HE in the classical limit, and that the diagonal part is reduced to Ohm's conductivity in the Drude model. This result indicates that the energy dissipation term is appropriately incorporated into the present ed-tdCDFT. A key contribution is the unified explanation of Ohm's law, the HE, and the IQHE, using a single theoretical framework.
