Effect of ammonia-derived species on visible-light photocatalytic activity of Au supported on amorphous TiO2 activated by plasma

Amorphous TiO2 supported Au photocatalyst (Au/AmT) is prepared via modified impregnation method with ammonia washing, followed by cold plasma treatment to activate the photocatalysts. Residual ammonia ([NH3](s)) is formed due to the hydrogen bond between surface OH groups on AmT and ammonia. The [NH3](s) suppressed the reduction of Au delta+ and occupied active sites, leading to a poor activity of as-prepared Au/AmT. The performance of cold plasmas in activation strongly depends on discharge gases. N-2 and O-2 plasmas not only cannot reduce Au delta+ into Au-0 but also convert [NH3](s) into poisoning species [NOy](s) during activation. H-2 plasma with a strong reducibility can simultaneously reduce Au delta+ and remove [NH3](s), thus enabling Au/AmT to achieve the highest visible-light photocatalytic activity in CO oxidation.