Visible-Light Induced Sustainable Water Treatment Using Plasmo-Semiconductor Nanogap Bridge Array, PNA

The development of sustainable methods for energy-intensive water treatment processes continues to be a challenging issue. Plasmonic-semiconductor nanoparticles, which absorb large amounts of sunlight in the visible range for conversion into chemical energy efficiently, can form the basis of a sustainable water treatment method. However, the potential uses of plasmonic semiconductor particles for water treatment have not been fully explored yet because of the limitations associated with the imbalance between light capture, charge transfer, and the required recycling steps for the particles themselves. Herein, a significantly improved visible-light-induced water treatment method that uses a plasmo-semiconductor nanogap bridge array (PNA) is reported. As an arrangement of antenna-reactors, the PNA enables the balancing of the largely enhanced electromagnetic field in the plasmonic nanogap coupling region and optimal separation of charge carriers in the semiconductor. The simultaneous effects of visible-light absorption and charge transfer lead to the generation of a highly enhanced visible-light-induced OH radical (•OH). Consequently, visible-light-induced 5-log N/N₀ water disinfection and 100% chemical decomposition for sustainable water treatment were demonstrated. Owing to the large light absorption, charge carrier utilization, and array-oriented scalability, the PNA will be valuable in various sustainable energy and environmental applications.