Construction of WO3/Ti-doped WO3 bi-layer nanopore arrays with superior electrochromic and capacitive performances

Crystalline WO3/Ti-doped WO3 bi-layer nanopore arrays were constructed by the template synthesis of a WO3 nanopore layer modified by a magnetron sputtering of an amorphous Ti-doped/WO3 layer. The obtained bi-layer nanopore array shows a remarkable electrochromic performance with large dual-band optical modulation in both visible (VIS) and near infrared (NIR) regions (optical modulation of over 70% in the wavelength range from 600 to 1600 nm) and the fast response speed (coloring for 3.4 s and bleaching for 6.6 s). In addition, the bi-layer WO3/Ti-doped WO3 nanopore array also present superior energy-storage properties (areal capacitance of 44.0 mF cm(-2) and good rate capability), better than that of titanium-free thin films. The special bifunctional characteristics of electrochromism and pseudocapacitance can be ascribed to the large specific surface area provided by the architectural design, rich ion channels in the amorphous layer as well as proper titanium doping, which bestows the bi-layer nanopore array a great potential in clean energy applications.