Controllable growth of high-quality metal oxide/conducting polymer hierarchical nanoarrays with outstanding electrochromic properties and solar-heat shielding ability

Abstract

The high performance of organic/inorganic hybrid materials relies largely on a scrupulous design of nanoarchitectures so that the organic and inorganic phases can work synergistically. We present a powerful two-step solution-based method for the fabrication of hierarchical metal oxide/conducting polymer heterostructured nanoarrays. Demonstrated examples include different nanostructures (nanorod arrays, nanorod-based networks and nanoplate arrays) of metal oxides (WO₃ and NiO) and PANI (nanostubs, nanoparticles and nano-wrinkles). Given the unique composition and architecture, the hierarchical NiO/PANI nanoplate arrays show reversible multicolor changes, fast switching speeds of 90 and 120 ms for coloration and bleaching states, respectively, and a superior coloration efficiency of 121.6 cm² C⁻¹ under a low voltage of 1.2 V. Additionally, the application of the NiO/PANI nanoplate array coated FTO glass causes a temperature difference of 7–7.6 °C under different ambient temperatures, making it very attractive for potential applications in energy-saving smart windows. Our strategy paves the way for the design and synthesis of hierarchical metal oxide/conducting polymer nanoarrays with enhanced properties for new applications.