Plasmonic degradation of plastics on gold nanoparticles: electronic-scale insights from computation

The growth in demand for plastic products in our rapidly industrializing society has led to a surge in global plastic production. Plasmonic nanostructures can harness light energy for catalytic reactions, presenting a promising avenue for catalyzing plastic degradation. Through real-time, time-dependent density functional theory (RT-TDDFT) simulations, we find that plasmonic systems can significantly enhance photodegradation of polymers and we study the mechanism of plasmon-driven photodegradation. We first benchmark our methods by studying gas-phase monomers and achieve qualitative agreement between our methods and what is experimentally known: the gas-phase monomers react significantly to an applied field (i.e., light) only for photosensitive polymers. We next find that gold nanoparticles can significantly enhance the degradation of both photosensitive and non-photosensitive monomers and oligomers. Interestingly, if any part of the oligomer is near the nanoparticle, the entire oligomer degrades, indicating that the degradation may be relatively long-ranged on the molecular scale. We also find that charge separation between C and H atoms correlates strongly with photodegradation for polyethylene oligomers.