Improving Photocatalytic H2O2 Production over iCOF/Bi2O3 S-Scheme Heterojunction in Pure Water via Dual Channel Pathways

Solar photocatalysis is a green, economical, and sustainable method for H 2 O 2 synthesis, which has been regarded as the most promising alternative to the traditional anthraquinone oxidation method. However, single-component photocatalyst exhibits moderate activity owing to the limited light-harvesting range, fast charge recombination and inadequate redox capacity. Moreover, the addition of sacrificial agents is required in the reaction system. Herein, we present the development of an S-scheme heterojunction, achieved through photodepositing Bi 2 O 3 nanoparticles (BO) on ionic covalent organic framework nanofiber (iCOF). The optimized photocatalyst iCOF/BO10 shows the highest H 2 O 2 production performance in pure water, achieving an H 2 O 2 yield of 9.76 mmolꞏg −1 ꞏh −1 with an apparent quantum yield (AQY) of 5.5% at 420 nm. This photocatalytic performance is approximately 2.2 and 5.6 times as high as that of pristine iCOF and BO, respectively. In-depth characterizations including in situ irradiated XPS, DFT-calculations, active species trapping experiments and in situ DRIFTS , reveal that the obtained sample not only facilitates charge carrier separation and enhances light absorption capability, but also maximizes the redox ability to concurrently achieve indirect 2e − ORR and 4e − WOR for H 2 O 2 production. Additionally, the generated O 2 from the 4e − WOR is capable of accelerating the reaction kinetics for H 2 O 2 formation via the indirect 2e − ORR pathway, enabling overall photocatalytic H 2 O 2 synthesis. This work provides a new insight into creating innovative catalysts for achieving high-efficiency photosynthesis of H 2 O 2 . Download: Download high-res image (84KB) Download: Download full-size image