Intrinsic Au-decoration on anodic TiO2 nanotubes grown from metastable Ti-Au sputtered alloy allows for high density co-catalyst decoration and enhanced photocatalytic H2 evolution

Recent work demonstrated that intrinsic Au nanoparticle decoration of TiO2 nanotube arrays (NTs) can be achieved by electrochemical anodization of Ti-Au alloy substrates. However, for a Ti-Au cast produced by melt-alloying, the Au concentration cannot exceed the solubility limit of Au in Ti of 0.2 at.% - this limits the intrinsic Au nanoparticle loading on anodic TiO2 NTs. Here we explore “metastable” Ti-Au metal substrates that are produced by Ti and Au cosputtering and we establish Au concentrations that far exceed the solubility limit in cast Ti-Au alloys. We show the use of these “metastable” Ti-Au sputtered layers for the anodic formation of TiO2 NTs with a much higher density of Au nanoparticle loading than using classic alloys. Using optimized conditions (Au nanoparticle density) for photocatalytic H2 production from such Au@TiO2 platforms provides a 15 times higher photocatalytic H2 evolution rate than the best rates achieved with conventional alloys.