Abstract
Photocatalytic CO2 reduction provides a promising strategy for the alleviation of greenhouse effect and energy shortage problem.Metal single atom modification is an effective method to improve the CO2 re-duction performance of covalent organic framework(COF)photocatalysts,while the intrinsic mechanism is not revealed in depth.Herein,a Pt-COF photocatalytic system was constructed by embedding Pt sin-gle atom in TFPT-TMT-COF(TFPT:1,3,5-tris(4-formylphenyl)-triazine,TMT:2,4,6-trimethyl-1,3,5-triazine).Based on density functional theory(DFT)calculation,the geometric structure and electronic property of Pt-COF were investigated,and the CO2 adsorption and reduction reaction process on Pt-COF were simu-lated.The results show that the Pt atom can be steadily anchored in COF via the formation of Pt-N and Pt-C bonds.Moreover,there is strong electronic interaction between Pt and COF.The incorporation of Pt atom benefits the CO2 reduction activity of COF from multiple aspects:(ⅰ)reducing the band gap and improving light absorption;(ⅱ)enhancing CO2 adsorption and activating the CO2 molecule;(ⅲ)decreas-ing the energy barrier in the hydrogenation step of CO2→COOH,thus facilitating CO2 conversion to CO;(ⅳ)inhibiting the hydrogenation of CO,thereby increasing the selectivity of CO.This work brings a novel insight into the excellent CO2 reduction performance of Pt modified COF,and provides useful references for the design of single atom photocatalysts.
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