Single‐crystal SnO2 nanorods were grown on rutile TiO2 with a heteroepitaxial relation of SnO2{001}/TiO2{001} (SnO2‐NR#TiO2) by a hydrothermal reaction. Resulting compressive lattice strain in the SnO2‐NR near the interface induces a continuous increase in the a‐axis length extending over 60 nm to relax towards the [001] direction from the root to the tip. UV‐light irradiation of the robust SnO2‐NR#TiO2 stably progresses the selective oxidation of ethanol to acetaldehyde with an external quantum yield of 25.6 % at excitation wavelength (λex)=365 nm under ambient temperature and pressure. Spectroscopic analyses and density functional theory simulation results suggested that the extremely high photocatalytic activity stems from the smooth interfacial electron transfer from TiO2 to SnO2‐NR through the high‐quality junction and subsequent efficient charge separation due to the lattice strain‐induced unidirectional potential gradient of the conduction band minimum in the SnO2‐NR.

SnO2 nanorods were hydrothermally grown on rutile TiO2 seed crystals (SnO2–NR#TiO2), where symbol # denotes the heteroepitaxial junction between SnO2 and TiO2. Furthermore, Au nanoparticles (NPs) were loaded on the surfaces of TiO2 and SnO2 of SnO2–NR#TiO2 by the deposition precipitation method (Au/[SnO2–NR#TiO2]). Au/[SnO2–NR#TiO2] possesses broad and strong absorption due to the localized surface plasmon resonance (LSPR) of Au NPs around 550 nm, while both TiO2 and SnO2 are almost transparent to visible light. On excitation of the LSPR (λex > 430 nm), Au/[SnO2–NR#TiO2] exhibits much higher photocatalytic activity for two-electron oxygen reduction reaction than two-component systems of Au/TiO2 and Au/SnO2 and their physical mixture. The striking photocatalytic activity of the three-component system stems from the efficient charge separation due to the LSPR-driven vectorial interfacial electron transfer in the direction of Au (on TiO2) → TiO2 → SnO2 → Au (on SnO2). Consequently, Au NPs on TiO2 and SnO2 work as the oxidation and reduction sites, respectively, and thus, the excellent electrocatalytic activity of Au NP for two-electron oxygen reduction reaction and low catalytic activity of SnO2 for H2O2 decomposition would also contribute to the high photocatalytic activity.

Thin heteroepitaxial layers of RuO2 were formed on the TiO2 surface of Au nanoparticle-loaded rutile TiO2, and this three-component nanohybrid exhibits a high photocatalytic activity for hydrogen peroxide generation from water and oxygen.

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