First-principles calculations on the structures and electronic properties of the TMW₂O_n (TM = Mn–Ni, n = 1–6) clusters

Transition metals can enhance the electronic attributes of tungsten oxides. In this study, we focused on W₂O_n (n = 1–6) clusters as a representative examples of tungsten oxide clusters with varying oxygen concentrations. The structures and electronic properties of the TMWO_n (TM = Mn–Ni) clusters have been calculated using first-principles. The ground-state TMWO_n clusters share some structural similarities with the ground-state W₂O_n (n = 1–6) clusters. The W–O bonds of the TMWO₂ (TM = Fe–Ni) clusters are significantly distorted into a triangular structure. The NiWO_n (n = 1–2) and CoWO_n (n = 3–5) clusters display greater thermodynamic stability than other TMWO_n clusters. Among the TMWO_n clusters, the W₂O₄, W₂O₆, MnWO, MnWO₃, MnWO₆, FeWO, FeWO₄, FeWO₆, CoWO, CoWO₆, NiWO₂, NiWO₅ clusters are more kinetically stable. Furthermore, the amount of charge transfer between the TM atoms and W₂O_n clusters increases from 0.050 |e| to 1.066 |e| as the number of oxygen atoms increases. The 4s orbital electrons of the TM atoms for the TMWO_n clusters are partially transferred to the neighboring O atoms.