Hydrogen peroxide (H2O2) photosynthesis combined with biomass value-added maximizes energy use and enables the production of high value-added products. Based on this,Professor Lan Yaqian and Professor Chen Yifa of South China Normal University, Professor Yu Fei of Nanjing Normal University, etcA series of COFS (Cu3-BT-COF, Cu3-PT-COF and TFP-BT-COF) with regulated redox molecular junctions were reported, and the reaction of H2O2 with furfuryl alcohol (FFA) photooxidation was studied. Among them, the Fa generation efficiency of Cu3-BT-CoF can reach 575 mm G-1**, and the rate of ** is about 100%. selectivity of more than 99%), and the yield of H2O2 was as high as 187000 M g-1, which was much higher than that of Cu3-PT-COF, TFP-BT-COF and their monomers.
Using DFT calculations, the authors investigated the possible mechanism of the coupling of H2O2 photosynthesis with FFA photooxidation. The differential charge density was used to analyze the charge distribution of Cu3-BT-COF structure, and it was found that the electrostatic potential value around BT was positive, indicating that this region was more likely to obtain electrons than Cu3 and had stronger electrophilicity. At the same time, the authors also calculated the adsorption energies of FFA and O2 at the possible adsorption sites of Cu3 and BT units. The adsorption energies of FFA on Cu3 and Bt were -5., respectively92 EV and -566 EV, indicating that FFA adsorbs Cu3 more easily than BT, while O2 has an adsorption energy of -3 on Cu3 and BT, respectively59 EV and -52 EV, indicating that BT adsorbs O2 more easily than FFA.
In addition, the authors also calculated the free energies of the ORR and FOR pathways of Cu3-BT-COF. In general, the reaction of ORR to H2O2 consists of three basic reactions (O2 O2 Hooh HoH, * represents the catalytic site), of which the last step (*Hooh HoH) is the constant rate step (RDS) with an energy barrier of -12 ev。where the free energies corresponding to the formation of *O2 and *hooh are -0., respectively29 EV and -138 ev。*O2 generation of *HOOH corresponds to two hydrogenation steps, where H comes from FFA dehydrogenation. The results show that the FFA dehydrogenation step, as the RDS step of FFA photooxidation, is closely related to the stepwise hydrogenation of O2 in H2O2 photosynthesis.
regulation of redox molecular junctions in covalent organic frameworks for h2o2 photosynthesis coupled with biomass valorizations. angew. chem. int. ed.,