The growth demand for plastic products in our rapidly industrializing society has led to a surge in global plastic production. Plastic’s properties such as non-biodegradability, complicated structure, and limited water solubility makes it challenging to break down. This study proposes an innovative approach utilizing plasmonic nanostructures for the efficient degradation of plastics. Plasmonic nanostructures harness light energy for catalytic reactions, presenting a promising avenue for sustainable plastics recycling.
Through real-time, time-dependent density functional theory (RT-TD-DFT) simulations, we investigated the response of photosensitive and non-photosensitive monomers when subjected to oscillating electric fields to simulate visible light in the presence of gold nanoparticles and in the gas phase. For the gas-phase calculations, we achieve qualitative agreement between our methods and what is experimentally known: the gas-phase monomer significantly reacts to the field (i.e., light) only if the polymer is known to be photosensitive. Our calculations that include gold nanoparticles show that we can break both photodegradable and non-photodegradable monomers’ and oligomers’ bonds by subjecting them to visible light, with some significant bond activation, more than 10 Å from the gold nanoparticle. The dramatic increase in light-driven degradation when gold nanoparticles are included demonstrates the potential of plasmonic nanoparticles in plastic degradation. We also elucidate the mechanisms underlying plastic degradation on plasmonic nanoparticles, including the effects of charge transfer and local electric field enhancement.

Response of gas-phase monomers to an applied, oscillating electric field with a Gaussian envelope. For each, the photosensitivity of the corresponding polymer is noted in the Photodegradable column. The applied field had a frequency of 2.5 or 4 eV, (visible light and upper UV region of solar spectrum), and a maximum amplitude of 0.1 Ry bohr^–1 e^–1 in the x, y, and z directions.

Noshir Pesika

Tulane University

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