Weakened Crystalline SnNb₂ O₆ for Enhanced Performance in Photocatalytic H₂ Production and CO₂ Reduction

Low crystalline photocatalysts with unsaturated active sites, such as oxygen vacancy (O_v ), is reported to exhibit enhanced adsorption and activation of oxygen-containing small molecules, such as H₂ O and CO₂ , thus boosting the activity in photocatalytic H₂ evolution and CO₂ reduction. However, numerous low-crystalline photocatalysts show unsatisfactory stability due to the easily repaired surface O_v . Herein, three SnNb₂ O₆ with different crystallinity were prepared by hydrothermal approach with similar precursors. Compared with bulk SnNb₂ O₆ and ultra-thin layered SnNb₂ O₆ , low-crystalline SnNb₂ O₆ (SNA) exhibits optimal visible-light-driven evolution rates of H₂ (86.04 μmol g^-1  h^-1 ) and CO from CO₂ (71.97 μmol g^-1  h^-1 ), which is mainly ascribed to the fast separation of the photogenerated carriers and enhanced photoreduction power caused by the surface O_v . More importantly, the sharp decrease of photocatalytic activity of SNA after seven cycles is well restored by the hydrothermal treatment of recycled SNA, ascribed to the reactivated surface O_v with the recovered low-crystalline structure. These works thus offer a promising strategy for developing low-crystalline and amorphous photocatalysts with high activity and stability.