Photoionization of methylphenothiazine in palladium ion-exchanged SAPO-5 and SAPO-11 silicoaluminophosphate microporous materials

Abstract

Palladium ion-exchanged SAPO-5 and SAPO-11 silicoaluminophosphate microporous materials were examined for the photoionization of N-methylphenothiazine (PC1) with 320 nm irradiation at room temperature. Photoionization of Pd-containing SAPO-5 and SAPO-11 materials results in the formation of N-methylphenothiazine radical cations (PC1+). The radicals were identified by electron spin resonance (ESR). The PC1+ yield was found to increase with increasing Pd content suggesting that the Pd ion serves as the electron acceptor site. The photoefficiency depends on the nature of the Pd species, the Pd content, and the channel size of the SAPO material. It is noteworthy that the photoyield of methylphenothiazine cation radical is higher in solid-state ion-exchanged Pd-SAPO materials compared to other hosts including alpha-ZrP, NiVPI-5, M-ETS-10, Ti-MCM-41, VAPO-5, CrH-SAPO-8, Cu-X and CuH-UHM-3.