Fabrication of metal oxide nanobranches on atomic-layer-deposited TiO₂ nanotube arrays and their application in energy storage

Due to the chemical stability and easy fabrication by atomic layer deposition (ALD), TiO₂ nanotubes are regarded highly useful in constructing branched nanostructured electrodes for solar conversion and electrochemical energy storage devices. Here we present a facile and scalable fabrication of metal oxide nanobranches on ALD pre-formed TiO₂ nanotubes. The metal oxide branches can be a wide range (nearly any) of desirable materials, including NiO and Co₃O₄ demonstrated herein. As an example, the TiO₂/NiO nanoarray battery cathode exhibits a relatively high gravimetric capacity value of ∼153 mA h g^-1 and a fairly good stability up to 12,000 cycles with a capacitance of 132 mA h g^-1 at 2 A g^-1.