A novel Ag@TiON/CoAl-layered double hydroxide photocatalyst with enhanced catalytic memory activity for removal of organic pollutants and Cr (VI)

Recently, photocatalysts with catalytic memory effect have attracted significant attention, for their ability to maintain excellent catalytic performance in the dark. However, the activities of current catalytic memory materials are still low because of their limited electron storage capacity. Here a novel Ag@TiON/Co-Al-layered double hydroxide (LDH) photocatalyst with enhanced catalytic memory activity is successfully synthesized by a dark deposition method. The introduction of nitrogen and hybridization with LDH shift the absorption edge of TiO2 into the visible light range (around 460 nm), which effectively promotes light absorption and charge separation. The dark deposition method inhibits the growth of Ag nanoparticles and the formation of Ag2O, which greatly improves the electron storage capacity of the hybrid. The enhanced photoactivity and catalytic memory activity of Ag@TiON/CoAl-LDH are confirmed through various experiments, including the photocatalytic degradation of methyl orange (MO) (94%) and dark reduction of Cr(VI) (61%). This work provides a new concept for improving the catalytic memory activity and reveals that coupling photoactivity and the catalytic memory effect may open a new avenue for the design of a round-the-clock catalyst. Such catalysts are also be expected to find applications in other fields, such as continuous disinfection and energy storage.