Spinel metal-doped magnesium ferrite (MgFe ₂ O ₄ ) was synthesized using an atmospheric hydrochloric acid leaching process and hydrothermal synthesis process from saprolite laterite.

The orientation controlled synthesis of h-WO₃ nanostructures on ITO substrates has been successfully realized in large scale via a simple hydrothermal method. The influences of pH value and growth time on the orientation and morphology of WO₃ nanostructures were investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The nanorod bundles parallel to ITO substrate and nanorod arrays vertical to ITO substrate can be selectively prepared by adjusting the final pH value just to 2.0 and 2.4, respectively. The morphology evolution and the growth mechanism of well aligned WO₃ nanorod arrays were intensively studied. Moreover, the optical properties of the WO₃ with different oriented alignment were also examined.

Tungsten oxide possesses electrochromic and pseudocapacitive properties; integrating these two functions into a single device with improved comprehensive performance has become a hot research topic. In this paper, bifunctional aligned hexagonal/amorphous tungsten oxide core/shell nanorod arrays (denoted as h@a-WNRAs) were fabricated on fluorine-doped tin oxide substrates by a two-step process involving hydrothermal treatment and spin coating to provide enhanced electrochromic and capacitive properties. The first step involved synthesis of single-crystalline hexagonal tungsten trioxide (h-WO₃) nanorod cores. The second step coated amorphous WO_x (a-WO_x) shells with thicknesses of 2–8 nm on the surface of the h-WO₃ cores. The results indicated that the a-WO_x shells strongly affected the electrochromic and pseudocapacitive properties of the heterostructure because of their high specific surface area and porous internal structure. Compared with that of pure WO₃ nanorod arrays, the optimized nanostructured h@a-WNRAs showed marked improvement of electrochromic and pseudocapacitive performance. In terms of electrochromic properties, the optimized h@a-WNRAs realized a substantial optical modulation (67.7%), short response times (15 and 21 s), high coloration efficiency (101 cm² C⁻¹ at 800 nm), and good cycling stability. Meanwhile, the optimized h@a-WNRAs also displayed promising pseudocapacitive properties, including a high specific capacitance (885.8 F g⁻¹ at 1 A g⁻¹), enhanced rate capability, good cycling efficiency (91.8%), and good specific capacitance retention (57.8% after 2000 cycles). The h@a-WNRA heterostructure obtained by this facile approach represents a new idea for the preparation of bifunctional materials with excellent electrochromic and pseudocapacitive properties.