Charge transfer in triphenylamine-tetrazine covalent organic frameworks for solar-driven hydrogen peroxide production

Hydrogen peroxide is a clean and valuable oxidant that can be produced by photocatalysis under visible light. Developing efficient metal-free photocatalysts for this reaction is a key challenge. To address this challenge, we make two crystalline vinyl-linked covalent organic frameworks, ATP-COF-1 and ATP-COF-2, which contain triphenylamine and tetrazine units. ATP-COF-1 has a hydrogen peroxide production rate of 14,000 μmol g^-1h^-1 with an apparent quantum yield of 23.05%, while ATP-COF-2 reaches 12,700 μmol g^-1h^-1 and 20.38%. The higher activity originates from efficient photoinduced charge separation, driven by electron transfer between the electron-donating triphenylamine and electron-accepting tetrazine components. Ultrafast spectroscopy confirms prolonged excited-state lifetimes of 351.9 and 277.3 picoseconds, consistent with enhanced charge mobility. In this work, we show that integrating donor-acceptor building blocks within covalent organic frameworks enables efficient and stable visible-light-driven hydrogen peroxide production.