Sulfone-Modified Covalent Organic Frameworks Enabling Efficient Photocatalytic Hydrogen Peroxide Generation via One-Step Two-Electron O 2 Reduction.

Photocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H 2 O 2 ) synthetic strategy, especially the one-step two-electron (2e - ) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one-step 2e - ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS-COFs), we present an efficient photocatalyst for H 2 O 2 generation via one-step 2e - ORR from pure water and air. Under visible light irradiation, FS-COFs exert a superb H 2 O 2 yield of 3904.2 μmol h -1  g -1 , outperforming most reported metal-free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron-hole (e - -h + ) pairs, enhance the protonation of COFs, and promote O 2 adsorption in the Yeager-type, which jointly alters the reaction process from two-step 2e - ORR to the one-step one, thereby achieving efficient H 2 O 2 generation with high selectivity.