Efficient Photocatalytic Production of H2O2 over ZnO/D-A Conjugated Polymer S-Scheme Heterojunction and Charge Transfer Dynamics Investigation
Photocatalytic technology harnesses clean,non-polluting solar energy to synthesize hydrogen peroxide(H2O2).In this study,ZnO/PBD S-scheme heterojunction composites,featuring ZnO nanoparticles on a donor-acceptor conjugated polymer substrate(PBD),were synthesized via the Suzuki-Miyaura reaction and hydrothermal method.The optimal ZnO/PBD composite achieved an H2O2 production efficiency of 4.07 mmol·g-1·h-1,which is 5.4 times higher than that of pristine ZnO.This significant enhancement is attributed to the formation of S-scheme heterojunctions.The successful construction of S-scheme heterojunctions was confirmed through UV-visible absorption spectroscopy and in situ irradiated X-ray photoelectron spectroscopy.Steady-state photoluminescence and femtosecond transient absorption(fs-TA)spectroscopies identified and verified the presence of defect states in ZnO.These defect states trap photogenerated electrons,adversely affecting the photocatalytic reaction.However,the S-scheme heterojunction effectively promotes the separation and transfer of electrons,mitigating this issue.The measured lifetimes of photogenerated electrons in these defect states,as determined by fitted fs-TA decay kinetics,provided further evidence of the carrier transfer mechanism in S-scheme heterojunctions.This work introduces a novel approach for studying organic/inorganic S-scheme heterojunctions using fs-TA spectroscopy.
Photocatalytic production of H2O2S-scheme heterojunctionZnO defect statesfs-TA spectroscopy
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