Rationally Designed Cyclooctatetrathiophene-Based Porous Aromatic Frameworks (COTh-PAFs) for Efficient Photocatalytic Hydrogen Peroxide Production.

Abstract

Constructing stable and efficient photocatalysts for H2 O2 production is of great importance and is challenging. In this study, the synthesis of three photoactive cyclooctatetrathiophene (COTh)-based porous aromatic frameworks (COTh-PAFs) in an alternating donor-acceptor (D-A) fashion is presented. In combination with a triazine-derived electron acceptor, PAF-363 exhibits high efficiency for the photosynthesis of H2 O2 with production rates of 11733 μmol g-1  h-1 (with sacrificial agent) and 3930 μmol g-1  h-1 (without sacrificial agent) from water and oxygen under visible light irradiation. Experimental results and theoretical calculations reveal that the charge transfer positions and the O2 adsorption sites in PAF-363 are both concentrated on COTh fragments, which facilitate the H2 O2 production through the oxygen reduction reaction (ORR) pathway. This work highlights that the rational design of COTh-PAFs with consideration of D-A direction, charge transfer positions, and O2 adsorption sites provides a feasible access to efficient H2 O2 production photocatalysts.