(321j) Titanium Dioxide Nanowires With Controllable Overpotential for Oxygen Evolution Reaction

Titanium dioxide (TiO₂) is one of the most widely studied semiconductors in photocatalysis because it is nontoxic, abundant, stable and photoactive. However, the wide bandgap, low electron mobility and short minority carrier diffusion length of TiO₂ limit its quantum efficiency in these applications. In this work, we present a large scale flux method for growing transition-metal doped TiO₂ nanowires. In this method, commercially available TiO₂ nanoparticles act as both nucleation seeds and reactant supply for nanowire growth within a matrix of common salt mixtures. Furthermore, in situ dopant incorporation of various transition metals allows for the tuning of optical, electrical, and catalytic properties. With this combination of control, robustness, and scalability, the molten-salt flux scheme can provide high quality TiO₂ nanowires to satisfy a broad range of application needs ranging from photovoltaics to photocatalysis. The transition-metal doped TiO₂ nanowires show improved visible light absorption, better transport properties and enhanced catalytic activity for oxygen evolution reaction (OER).