Photoluminescence of zirconium hydroxide: Origin of a chemisorption-induced ‘red-stretch’

Zirconium hydroxide particles are reactive and photoluminescent, emitting blue light under ultraviolet (UV) irradiation. Adsorption-induced changes in the photoluminescence (PL) offer opportunities for gas sensor/filtration applications. The PL of Zr(OH)4 is quenched in the presence of molecular oxygen, likely through trapping of surface electrons via the formation of O 2 - . Heating the powder high enough to desorb hydroxyl groups broadens the PL spectrum toward longer wavelengths. This ‘red-stretch’ also occurs upon reaction with sulfur dioxide, which replaces terminal hydroxyl groups with sulfite ones. Excessive UV irradiation correspondingly induces this effect. A mechanism is proposed to account for the red-stretch.