Weakened crystalline SnNb2O6 for enhanced performance in photocatalytic H2 production and CO2 reduction.

Abstract

Low crystalline photocatalysts with the unsaturated active site, such as oxygen vacancy (Ov), is reported to exhibit enhanced adsorption and activation of oxygen-containing small molecules, such as H2O 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 Ov. Herein, three SnNb2O6 with different crystallinity were prepared by hydrothermal approach with similar precursors. Compared with bulk SnNb2O6 and ultra-thin layered SnNb2O6, low-crystalline SnNb2O6 (SNA) exhibits optimal visible-light-driven evolution rates of H2 (86.04 μmolg-1h-1) and CO from CO2 (71.97 μmolg-1h-1), which is mainly ascribed to the fast separation of the photogenerated carriers and enhanced photoreduction power caused by the surface Ov. 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 Ov 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.