Single-Atom Photocatalyst as Floatable Artificial Leaf for Upcycling Oceanic Plastic Waste.

Area of Science:

• Materials Science and Engineering
• Environmental Chemistry
• Catalysis

Background:

• Global plastic production exceeds 8 billion tons, with 80% accumulating in landfills and oceans.
• Polypropylene (PP) has a recycling rate below 1%, necessitating innovative waste management strategies.
• Developing efficient methods for plastic upcycling is crucial for environmental sustainability.

Purpose of the Study:

• To prepare and characterize ruthenium single atoms (Ru SAs) loaded on ZnIn2S4 photocatalysts.
• To investigate the direct conversion of raw polypropylene (PP) plastic into valuable chemicals.
• To explore the potential of a floatable artificial leaf (AL) concept for plastic waste upcycling.

Main Methods:

• Synthesis of ZnIn2S4/Ru SAs photocatalysts in powder and floatable artificial leaf (AL) forms.
• Utilized in situ spectroscopic techniques (XPS, AFM-KPFM, EPR, PL, IR) to study reaction mechanisms.
• Employed transient photovoltage measurements and quenching experiments to elucidate catalytic processes.

Main Results:

• The optimized photocatalyst achieved a high production rate of 1022.5 µmol g⁻¹ for formic and acetic acid.
• Demonstrated efficient electron transfer from ZnIn2S4 to Ru SAs and subsequent O2 activation.
• Showcased electrolyte-assisted polarization in seawater significantly enhancing charge separation and transfer.

Conclusions:

• Ru SAs on ZnIn2S4 photocatalysts effectively upcycle PP plastic into valuable chemicals.
• Reactive oxygen species (·O2⁻ and ·OH) play a critical role in the plastic conversion process.
• The floatable AL concept offers a promising and sustainable approach to address plastic pollution.