TiO(x)/Pt(3)Ti(111) surface-directed formation of electronically responsive supramolecular assemblies of tungsten oxide clusters

Highly ordered titanium oxide films grown on a Pt(3)Ti(111) alloy surface were utilized for the controlled immobilization and tip-induced electric field-triggered electronic manipulation of nanoscopic W(3)O(9) clusters. Depending on the operating conditions, two different stable oxide phases, z’-TiO(x) and w’-TiO(x), were produced. These phases show a strong effect on the adsorption characteristics and reactivity of W(3)O(9) clusters, which are formed as a result of thermal evaporation of WO(3) powder on the complex TiO(x)/Pt(3)Ti(111) surfaces under ultra-high vacuum conditions. The physisorbed tritungsten nano-oxides were found as isolated single units located on the metallic attraction points or as supramolecular self-assemblies with a W(3)O(9)-capped hexagonal scaffold of W(3)O(9) units. By applying scanning tunneling microscopy to the W(3)O(9)–(W(3)O(9))(6) structures, individual units underwent a tip-induced reduction to W(3)O(8). At elevated temperatures, agglomeration and growth of large WO(3) islands, which thickness is strongly limited to a maximum of two unit cells, were observed. The findings boost progress toward template-directed nucleation, growth, networking, and charge state manipulation of functional molecular nanostructures on surfaces using operando techniques.