Functionalized amorphous TiO2 (AmT) with high surface area and abundant surface hydroxyl groups could be a promising support for plasmonic Au/TiO2 nanocatalysts. To overcome the limitations of conventional heat treatment on plasmonic Au/AmT nanocatalysts, cold hydrogen (H-2) plasma activation is employed and makes it possible to achieve superior visible-light (VL) photocatalytic activity and durability. Catalyst characterization results suggest that H-2 plasma can activate Au/AmT nanocatalysts to form high levels of metallic Au with strong surface plasmon resonance, low charge transfer resistance, and a unique interface between Au nanoparticles and AmT support. Comparative study of Au/AmT and Au/P25 (Degussa TiO2) activated by different plasmas (H-2 or O-2) reveals that the excellent performance of H-2 plasma in Au/AmT activation originates from strong interaction between surface hydroxyl groups and Au precursors. This work offers the potential for preparing VL photocatalytic Au/AmT films on flexible substrates for extensive applications in photocatalysis and solar cells. (C) 2019 Elsevier Inc. All rights reserved.