Engineering a Z-Scheme Heterostructure on ZnIn₂S₄@NH₂-MIL-125 Composites for Boosting the Photocatalytic Performance

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) show promise in photocatalysis but require strategies to improve efficiency.
• Z-scheme heterostructures are effective for enhancing photocatalytic performance by facilitating charge separation.

Purpose of the Study:

• To design and fabricate an internal electric field (IEF)-induced Z-scheme heterostructure on a MOF composite (ZnIn2S4@NH2-MIL-125).
• To investigate the charge transfer mechanism and its impact on photocatalytic activity.

Main Methods:

• Facile electrostatic self-assembly for fabricating the composite.
• In situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and photoirradiated Kelvin probe force microscopy (KPFM) to study charge transfer.
• Electron paramagnetic resonance (EPR) radical trapping and density functional theory (DFT) calculations to confirm the mechanism.

Main Results:

• The close interfacial contact and work function difference between ZnIn2S4 and NH2-MIL-125 create an IEF.
• The IEF effectively drives Z-scheme charge transfer, confirmed by experimental and theoretical analyses.
• The optimized ZnIn2S4@NH2-MIL-125 composite demonstrated significantly enhanced photocatalytic activity for 4-nitroaniline reduction.

Conclusions:

• The IEF-induced Z-scheme heterostructure is a viable strategy for boosting MOF photocatalytic performance.
• This work provides fundamental insights into charge transfer mechanisms in Z-scheme systems.
• The findings offer valuable guidance for designing advanced MOF-based photocatalysts.