Interfacial Engineering of β-Ketoenamine-Based COFs/Urea-Linked Perylene Diimide for Overall Photosynthesis of H2O2 in Seawater

Abstract

High-efficiently non-sacrificial H2O2 production is challenging due to the sluggish kinetics of ORR and WOR and severe electron-hole recombination. Via interfacial engineering, a series of non-metal photocatalysts are rationally designed and constructed, covalently bonded TpDT-COF (TP) and urea-PDI (UP), to achieve high non-sacrificially photocatalytic H2O2 production in seawater. Experimental and theoretical analysis has revealed that an interfacial electric field is formed between covalently bonded TP and UP, which provides an internal driving force to enhance the electron-hole separation. Further mechanistic studies reveal that the H2O2 production follows a simultaneous two-step 2e− ORR and 4e− OER route. Moreover, the activity toward OER of the active center at the UP is significantly promoted due to a net charge transfer from UP to TP after covalently bonding. As a result, a high non-sacrificial H2O2 production rate of 3846 µmol gh−1 in seawater is achieved. Furthermore, a 4.7 mM H2O2 is obtained after a 13 h-continuous photocatalytic reaction, which can be directly used to purify dye and phenol contaminated water. Notably, the strategy of creating interfacial electric field coupled with desired charge transfer provides a universal approach for non-sacrificial photosynthesis by enhancing the electron-hole separation and activity of catalytic centers simultaneously.