Surface plasmon resonance effect cooperated with Z-scheme heterostructure for enhancing photocatalytic nitrogen...

The photocatalytic efficiency can be improved by constructing a Z-scheme heterojunction, but hindered by the only half utilization efficiency of photogenerated carriers. Thus, a novel material, UiO-66-NH₂@TAPB-BTCA-COP-Ag (U6N@COP-Ag), with surface plasmon resonance (SPR) effect synergistic Z-scheme heterostructure has been prepared by depositing Ag nanoparticles (Ag NPs) on TAPB-BTCA-COP (COP)-coated UiO-66-NH₂. The deposited Ag NPs expand the range of light absorption and introduce more photogenerated electrons in the composite. The SPR effect of noble metal compensates for the limited utilization of the Z-scheme heterojunction photogenerated carriers and the increased density of semiconductor carriers at the reducing end, which is more conducive to the redox reaction of the catalyst. Without sacrificial agents, U6N@COP-Ag shows great photocatalytic nitrogen reduction conversion efficiency with the rate of NH₄⁺ in ammonia water at 167.63μmol g^-1h^-1, which is 6.6 and 2.8 times that of the original UiO-66-NH₂ and COP, respectively. In-situ XPS and Kelvin probe technology verify that UiO-66-NH₂ and Ag nanoparticles provide more photogenerated electrons to COP. The cleavage and conversion of N₂ to NH₄⁺ on U6N@COP-Ag was confirmed by the enhancement of NH bonds and NH₄⁺ characteristic absorption peaks in the in-situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS). This work presents a great method to improve the Z-scheme heterojunction photogenerated carrier utilization and the density of semiconductor carriers at the reducing end by the noble metal SPR effect, which is more conducive to enhance the redox reaction of the catalyst.