Abstract
The intercalation of uncommon cations into WO3 lattice channels, including large monovalent cations (K+, Et4N+, CtMe3N+), transition metal dications (Ni2+) and heavy metal ions (Cd2+) in competition with H+ ions, have been investigated using pulse-nanogravimetric technique. For all metal ions, a large increase in the apparent mass uptake (up to 8-fold) in comparison to pure H+ ion ingress was observed upon film coloration, induced by a cathodic pulse. The experiments indicate that the apparent mass gains are insufficient for a predominant metal ion transport along the channels in WO3 lattice. The low de-coloration rate for Ni2+ ions has been attributed to slow dis-association of Ni2+ ions from lattice bound oxygen atoms. For the tetraethylammonium cation, a dissociative reduction of the WO3 and a severe lattice damage was observed. Among the metal ions, only K+ have been found to cause a dissociative reduction of WO3 and near-surface lattice damage.