Leveraging cooperative photocatalysis for the concurrent production of solar fuels and value-added chemicals: mediated by a metal-free porphyrin-based polymeric framework

Abstract

Limitations in the conventional energy-intensive anthraquinone oxidation process for H₂O₂ production have led researchers to develop an environmentally sustainable, energy-efficient, and cost-effective approach. The photocatalytic H₂O₂ generation from molecular oxygen has emerged as a leading edge in sustainable technology development, yet efficiency remains a key challenge. Various sacrificial agents are added to the reaction medium to improve efficiency, but their underutilization is the primary concern. To address this issue, we design a reaction system that considers the selective oxidation of the sacrificial agent along with the reduction of oxygen. Notably, we constructed a metal-free organic polymer Porp-Tz exhibiting broad visible light absorption and suitable band positions that consider the efficient reduction of O₂ for the co-production of H₂O₂ with a remarkable generation rate of 25.13 mmol g⁻¹ h⁻¹ along with the synthesis of industrially important chemical N-benzylidenebenzylamine (AQY = 7.9% at 420 nm). In addition, the concurrent production of regioselective 3,4-dihydroisoquinolines (DHIQs) from tetrahydroisoquinolines (THIQs) alongside the H₂O₂ generation rate of 13.34 mmol g⁻¹ h⁻¹ was explored. Moreover, the photocatalytic reaction mechanism highlights the synergistic role of the reactive oxygen species (O₂˙⁻ and ¹O₂), h⁺, and proton donors, providing a comprehensive understanding of the photocatalytic process. This study emphasizes new insights into deploying the next-generation multifunctional polymeric framework for the photocatalytic co-production of solar fuel and the selective synthesis of fine value-added chemicals, broadening the scope of porous organic polymers for potential industrial interest.