Our research interest is focused on construction of high-performance inorganic materials for artificial photosynthesis and biomass conversion, which are very important techniques in sustainable society. For artificial photosynthesis, we are making an effort to construct semiconductor photocatalysts with response to longer wavelengths and higher quantum yields. To achieve it, we examine control of band gaps and reactivity of electrons/holes through band potential tuning, surface modification for introduction of active sites and control of carrier traps, and synthesis processes. We also study properties of complex oxides as solid acid-base catalysts for biomass conversion. In addition, we are exploring new inorganic compounds capable of application to photocatalysts and solid acid-base catalysts.