Photocatalytic strategies for mitigating microplastic pollution and greenhouse gas emissions

Microplastics contaminate water, soil, and air, and their persistence is linked to greenhouse gas emissions. Photocatalysis can break down these polymers via reactive oxygen species but particle shrinkage alone does not prove complete mineralization. Recent photocatalytic systems are examined, including TiO 2 -based materials, S-scheme and Z-scheme heterojunctions, laddered architectures, metal-organic frameworks, and g-C 3 N 4 composites. These systems improve charge separation and visible-light harvesting, with some achieving high mineralization under optimized conditions. Verifying true breakdown requires TOC, LC-MS, and GC-MS because incomplete oxidation can produce toxic intermediates. Photocatalysis may also shorten plastic residence times and reduce methane and nitrous oxide emissions, though this depends on carbon fate, catalyst stability, energy inputs, and water chemistry. Combining photocatalysis with renewable energy and water treatment could offer a practical route to microplastic management, provided catalyst recovery, toxicity, and scale-up challenges are addressed.