Fabrication of WO3/TiO2 core-shell nanowire arrays: Structure design and high electrochromic performance

Unique WO3/TiO2 core-shell nanowire heterostructures are rationally constructed based on a solvothermal method combining magnetron sputtering. High resolution transmission electron microscopy (HRTEM) analysis evidences the existence of a semi-coherent interface between a hexagonal phase WO3 core and anatase TiO2 shell. X-ray photoelectron spectroscopy and optical absorption spectra suggest an interfacial interaction between the WO3 core and TiO2 shell. The WO3/TiO2 core-shell nanowires exhibit superior electrochromic performance in both visible and near infrared regions with large optical modulation (87.0% at 1500 nm and 85.3% at 633 nm), short bleaching–coloration times (1.1 s and 3.0 s), decent coloring efficiency (102.1 cm2 C−1) and excellent cycling stability (95.6% after 3000 cycles). The obtained WO3/TiO2 core-shell nanowire heterostructures may find great potential in producing electrochromic nanodevices and other energy-efficient applications.