Construction of S-scheme heterojunction from protonated D-A typed polymer and MoS2 for efficient photocatalytic H2 production
This study involves a heterojunction(denoted as PPMS)with an intimate heterointerface and S-scheme architecture,which consisted of a conjugated polymer of protonated PyDTDO-3 featuring a donor-acceptor(D-A)configuration and a 2D-layered MoS2.The optimal PPMS-0.5％heterojunc-tion exhibits a remarkable efficiency of 75.4 mmol g-1 h-1 in generating H2 when subjected to visible light illumination,representing an approximately 4.6 times enhancement compared to pure PyDTDO-3.To elucidate the photocatalytic mechanism,a range of characterization methods were utilized and calculations using density functional theory were carried out.The disparity in the work function between PyDTDO-3 and MoS2 results in the creation of a Fermi-level gap.Consequently,the establishment of a built-in electric field facilitates the occurrence of the electrons in MoS2 spon-taneously transferring to PyDTDO-3 at the interface.The consumption of hole on the valence band of MoS2 is accelerated by the electron transfer from the lowest unoccupied molecular orbital(LUMO)of PyDTDO-3,according to a kinetic study using femtosecond transient absorption spectra(fs-TAS).Moreover,the S-scheme PPMS exhibits a lower Gibbs free energy(ΔGH*,0.77 eV)in com-parison to the individual component,indicating it facilitates the formation of the transitional state(H*)and the effective desorption of molecular hydrogen on PPMS.Both the promoting directed charge migration and the increasing active sites contribute to the boosted photocatalytic H2 evolu-tion.
S-Scheme heterojunctionProtonated D-A typed polymerMoS2Photocatalytic hydrogen evolutionDensity functional theory calculation
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