Photosynthesis of hydrogen peroxide from dioxygen and water using aluminium-based metal–organic framework assembled with porphyrin- and pyrene-based linkers

Abstract

Photocatalytic production of hydrogen peroxide (H₂O₂) from dioxygen (O₂) and water (H₂O) has shown promise for the artificial photosynthesis of liquid fuel. We previously demonstrated that an Al-based metal–organic framework (MOF) functions as a suitable platform for photocatalytic H₂O₂ production owing to the efficient suppression of H₂O₂ decomposition caused by the photocatalysts themselves, which increases the yield of H₂O₂. However, the photocatalytic efficiency of Al-based MOFs is often limited by their short-lived charge separation. The energy transfer process is a beneficial approach to promoting charge separation and thereby improving the photocatalytic activity; MOFs enable highly efficient energy transfer between organic linkers because they allow precise control of the arrangement of the building blocks. Herein, we demonstrate that an Al-based MOF composed of both porphyrin- and pyrene-based organic linkers (Al-TCPP(10-X)-TBAPyX) is a promising photocatalyst for producing H₂O₂ from O₂ and H₂O without additives under visible-light irradiation while simultaneously enabling efficient suppression of undesired H₂O₂ decomposition. Efficient energy transfer from 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy) to tetrakis(4-carboxyphenyl)porphyrin (TCPP) was driven within Al-TCPP(10-X)-TBAPyX, resulting in dramatically enhanced photocatalytic H₂O₂ production through optimization of the linker mixture ratio in the MOF structure. The present work not only proposes a new reaction pathway for H₂O₂ generation via¹O₂ intermediates, which is quite different from well-accepted mechanisms involving O₂˙⁻, but also provides a promising strategy for designing catalysts to realize efficient photosynthetic H₂O₂ production.