Construction of 3D V₂O₅/hydrogenated-WO₃ nanotrees on tungsten foil for high-performance pseudocapacitors

3D semiconductor nanostructures have proved to be a rich system for the exploring of high-performance pseudocapacitors. Herein, a novel 3D WO ₃ nanotree on W foil is developed via a facile and green method. Both capacitance and conductivity of the WO₃ nanotree electrode are greatly improved after hydrogenation treatment (denoted as H-WO₃). First-principles calculation based on the experiments reveals the mechanism of the hydrogenation treatment effect on the 3D WO₃ nanotrees. The surface O of 3D WO₃ nanotrees gains electrons from the adsorbed H, and consequently certain electrons are back-donated to the neighboring W, thus providing the conducting channel on the surface. Ultrathin V₂O ₅ films were coated on the H-WO₃ nanotrees via a simple, low-cost, environmentally friendly electrochemical technique. This V ₂O₅/H-WO₃ electrode exhibited a remarkable specific capacitance of 1101 F g^-1 and an energy density of 98 W h kg^-1. The solid-state device based on the V₂O ₅/H-WO₃ electrodes shows excellent stability and practical application. Our work opens up the potential broad application of hydrogenation treatment of semiconductor nanostructures in pseudocapacitors and other energy storage devices.