Confining Bismuth‐Halide Perovskite in Mesochannels of Silica Nanomembranes for Exceptional Photocatalytic Abatement of Air Pollutants

Abstract Spatially confined photocatalysis has emerged as a viable strategy for the intensification of various redox reactions, but the influence of confined structure on reaction behavior is always overlooked in gas‐solid reactions. Herein, we report a nanomembrane with confining Cs 3 Bi 2 Br 9 nanocrystals inside vertical channels of porous insulated silica thin sheets (CBB@SBA(⊥)) for photocatalytic nitric oxide (NO) abatement. The ordered one‐dimensional (1D) pore channels with mere 70 nm channel length provide a highly accessible confined space for catalytic reactions. A record‐breaking NO conversion efficiency of 98.2 % under a weight hourly space velocity (WHSV) of 3.0×10 6 mL g −1 h −1 , as well as exceptionally high stability over 14 h and durability over a wide humidity range (RH=15–90 %) was realized over SBA(⊥) confined Cs 3 Bi 2 Br 9 , well beyond its nonconfined analogue and the Cs 3 Bi 2 Br 9 confine in Santa Barbara Amorphous (SBA‐15). Mechanism studies suggested that the insulated pore channels of SBA(⊥) in CBB@SBA(⊥) endow concentrated electron field and enhanced mass transfer that render high exposure of reactive species and lower reaction barrier needs for ⋅O 2 − formation and NO oxidation, as well as prevents structural degradation of Cs 3 Bi 2 Br 9 . This work expands an innovative strategy for designing efficient photocatalysts for air pollution remediation.