Preparation of Pt‐Intercalated KCa₂Nb₃O₁₀ Nanosheets and Their Photocatalytic Activity for Overall Water Splitting

Abstract Pt‐deposited KCa₂Nb₃O₁₀ restacked nanosheets were studied as water splitting photocatalysts under UV and visible irradiation (λ≥300 nm). Nanoparticulate Pt species were intercalated into the gallery space of KCa₂Nb₃O₁₀ restacked nanosheets by using the electrostatic interaction between the anionic nanosheets and a cationic Pt precursor, followed by H₂ reduction at 373–973 K. Although differences in the Pt size distribution were observed, Pt nanoparticles <2 nm in size were mainly deposited at temperatures below 673 K, owing to the suppression of Pt aggregation that originated from steric hindrance of the interlayer nanospace. On the other hand, the valence state of Pt varied from oxide to metal, accompanied with a change in the location from the interlayer space to the external surface, as the reduction temperature was increased. The highest water splitting activity was obtained at 473 K, where the Pt species were mainly loaded as nanoparticles that had <1 nm size and electron‐deficient states.