Red-light emission in MCM-41 meso-porous nanotubes

Photoluminescence has been used to study the red-light emission from siliceous MCM-41 with rapid thermal annealing (RTA). A broad emission ranging from 580 to 670 nm was observed and interpreted as non-bridging oxygen hole center (NBOHC). Based on the evolution of NBOHC after RTA, the hydroxyl group and peroxy linkage were demonstrated to be the possible precursors of NBOHC in siliceous MCM-41. We also found the photoluminescence intensity of NBOHC in MCM-41 degrade with time during photoexcitation. The degradation rate of NBOHC increases with increasing RTA temperature and excitation power. The degradation mechanism of photoluminescence may be associated with the recombination of the optically induced hydrogen species and NBOHC.