Photoredox Reaction

Abstract

A photoelectrochemical actuator based on poly(acrylic acid) gel loaded with TiO2 nanoparticles and copper(II) ions swells in a water-ethanol mixed solution under ultraviolet (UV) light due to photocatalytic reduction of copper(II) to copper (0) nanoparticles and oxidation of ethanol. After UV light irradiation, the hydrogel gradually shrinks again due to aerobic oxidation of copper nanoparticles to copper (II) ions. A photoelectrochemical actuator based on poly(acrylic acid) gel loaded with TiO2 nanoparticles and silver(I) ions also swells in water under UV light due to photocatalytic reduction of silver(I) to silver(0) nanoparticles and oxidation of water. The hydrogel shrinks again under visible light due to reoxidation of silver nanoparticles to silver(I) ions and reduction of oxygen molecules by the plasmoninduced charge separation. Partial swelling and shrinking of the hydrogel are also possible.