A black-colored nitrogen-doped calcium niobium oxide nanosheet with a thickness of around 1 nm was prepared by exfoliating nitrogen-doped layered oxide (KCa₂Nb₃O_10−xN_y), which exhibited photocatalytic activities superior to those of the parent material under visible light irradiation. It is suspected that the ultrathin thickness is suppressing the recombination.

There is a strong demand for the development of a large capacity rechargeable battery in various fields. Recently, we proposed the combination of solid oxide fuel cell technology with Fe–air battery concepts using H₂/H₂O as a redox mediator and a LaGaO₃-based oxide as an electrolyte. Because large internal resistance and large degradation during charge and discharge cycles were observed on the anode, there is a strong demand for improvements in discharge potential and cycle stability. This study investigates the use of a cermet anode consisting of a Ni–Fe alloy combined with an oxide ion conductor. It was observed that by using a cermet anode of Ni–Fe combined with Ce_0.6Mn_0.3Fe_0.1O₂ (CMF), the observed capacity of the cell was improved to 1163 mAh g⁻¹ Fe⁻¹ at 10 mA cm⁻² and 873 K. This is about 97% of the theoretical capacity by assuming the formation of Fe₃O₄ (1200 mAh g⁻¹ Fe⁻¹). Cycle stability of the cell was also considerably improved with the use of a Ni–Fe–CMF anode compared to a Ni–Fe anode because of the suppressed aggregation provided by the mixing of Ni with CMF.