Construction of Z-scheme heterojunction of PANI-Ag-CN sandwich structure with efficient photocatalytic hydrogen evolution

In this work, we report a sandwich structure of PANI-Ag-CN photocatalyst, which is stacked layer by layer with g-C3N4 and PANI ultra-thin two-dimensional nanosheets and Ag nanoparticles are embedded as interlayers. The Z-scheme heterojunction can be formed in this sandwich structure of PANI-Ag-CN photocatalyst, where Ag nanoparticles act as the charge transfer intermediate, leading to the annihilation of the holes of g-C3N4 and the electrons of PANI, and thus the strong reductive electrons and the strong oxidative holes can be left at the CB of g-C3N4 and VB of PANI, respectively. Meanwhile, the short charge transfer and the large number of active sites on the ultra-thin two-dimensional nanosheets are proved beneficial for to the photocatalytic hydrogen evolution from water. The PANI-Ag-CN photocatalyst exhibits an increased hydrogen evolution activity of 5048 mu mol.g(-1).h(-1), which is 43.52-fold higher than that of g-C3N4 and 58.02-fold higher than that of bulk g-C3N4. Moreover, the photocurrent of PANI-Ag-CN is 1.9 x 10(-6) A/cm(2), which is 5.94 times higher than that of g-C3N4.