Sulfone‐Modified Covalent Organic Frameworks Enabling Efficient Photocatalytic Hydrogen Peroxide Generation via One‐Step Two‐Electron O₂ Reduction

Abstract

Photocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2O2) 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 H2O2 generation via one‐step 2e− ORR from pure water and air. Under visible light irradiation, FS‐COFs exert a superb H2O2 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 O2 adsorption in the Yeager‐type, which jointly alters the reaction process from two‐step 2e− ORR to the one‐step one, thereby achieving efficient H2O2 generation with high selectivity.

Regulating Relative Nitrogen Locations of Diazine Functionalized Covalent Organic Frameworks for Overall H2O2 Photosynthesis

“…Notably, strong covalent linkages endow COFs with outstanding stability, benefiting practical applications. Recently, some research has been conducted to develop advanced COF‐based photocatalysts for H 2 O 2 generation [18–21] . However, the photocatalytic efficiencies are still unsatisfactory, and more active redox sites are yet to be explored.…”

An Unlocked Two‐Dimensional Conductive Zn‐MOF on Polymeric Carbon Nitride for Photocatalytic H2O2 Production

“…The photocatalytic performance of samples for H 2 O 2 production is assessed in a 20 vol % ethanol solution with O 2 under visible light irradiation. The generated amount of H 2 O 2 was measured using the colorimetric N,N‐diethyl‐p‐phenylenediamine (DPD) method (Figure S17, SI) [41–43] . The optimized nominal loading of Zn species and annealing temperature for CN/Zn‐MOF(lc) composites are determined to be 2 wt % and 400 °C, respectively (Figure 2a; Figure S18, SI).…”

“…This phenomenon is similar to the case when ethanol is used as the sacrificial agent. The tolerance of H 2 O 2 to the photocatalysts is another important parameter that needs to be considered [43,44] . CN/Co‐MOF/400, as a control sample, is prepared following the synthesis procedures of CN/Zn‐MOF(lc)/400, except that Co salts are used instead of Zn salts.…”

“…The generated amount of H 2 O 2 was measured using the colorimetric N,N-diethyl-pphenylenediamine (DPD) method (Figure S17, SI). [41][42][43] The optimized nominal loading of Zn species and annealing temperature for CN/Zn-MOF(lc) composites are determined to be 2 wt % and 400 °C, respectively (Figure 2a; Figure S18, SI). Bare CN and CN/Zn-MOF(lc) show a photocatalytic H 2 O 2 generation rate of 12.0 and 12.4 μmol h À 1 , respectively.…”

Regulating Relative Nitrogen Locations of Diazine Functionalized Covalent Organic Frameworks for Overall H2O2 Photosynthesis

“…Recently, some research has been conducted to develop advanced COF-based photocatalysts for H 2 O 2 generation. [18][19][20][21] However, the photocatalytic efficiencies are still unsatisfactory, and more active redox sites are yet to be explored.…”