Electrochromic Niobium Oxide Nanorods

Abstract

Niobium oxide (Nb 2 O 5 ) is an interesting active material for technologies ranging from catalysis and sensors to energy storage and electrochromic devices owing to its unique optical, electronic, and electrochemical properties. These properties vary between different phases and morphologies in the Nb 2 O 5 system, but systematic studies that correlate properties to phase and morphology are limited by current synthetic methods, which require postsynthetic high temperature treatments and suffer from a lack of direct and precise control over morphology, crystal structure, and stoichiometry. Here, we report a heat-up colloidal synthesis method that produces orthorhombic Nb 2 O 5 nanorods 1 nm in width by 31 nm in length that preferentially grow along the [001] direction. The synthesis is based on aminolysis of niobium oleate in octadecene, and nanorods are formed through three distinct steps: aminolysis-driven formation of niobium oxo clusters, condensation into amorphous Nb 2 O 5 seeds below the reaction temperature (240 °C, under atmospheric pressure), and crystallization and growth of Nb 2 O 5 nanorods. We investigated the electrochromic behavior of nanorod thin films upon Li + intercalation and observed predominantly near-infrared coloration, fast switching kinetics, and durability for at least 500 charge−discharge cycles.

Synthesis and Dual-Mode Electrochromism of Anisotropic Monoclinic Nb12O29Colloidal Nanoplatelets

“…The preparation of the niobium precursor was varied to control the outcome of synthesis. Pure NPLs are produced using niobium oxo cluster as the precursor while a mixture of mostly orthorhombic Nb2O5 nanorods (NRs), similar to those reported previously, 26 and some NPLs resulted when using niobium chloro oleate. The precursor formation chemistry was investigated, revealing the formation of niobium chloro oleate upon mixing NbCl5 and oleic acid (OA), and that subsequent heating cleaves the Nb-Cl bonds to form niobium oxo cluster.…”

“…The electrochromic properties of the NPLs are distinct from other phases and morphologies of niobium oxide and may be advantageous compared to other metal oxides for particular applications. The CE of NPLs are compared to literature values of relevant metal oxides in Table S1 26,[68][69][70] . First, the NPLs are the only materials can selectively modulate visible and NIR transmission among niobium oxides.…”

Formation and growth mechanism for niobium oxide nanoparticles: atomistic insight from in situ X-ray total scattering

“…photodetection 11 and in recent years, the potential of amorphous and nanostructured Nb2O5 for electrochromic windows has been investigated. [12][13][14] The versatility of applications of niobium-based oxides arises from their rich structural chemistry. 9,15 The building block of niobium pentoxide Nb2O5 is the [NbO6] octahedra which occur in the oxide structures as corner-sharing or edge-sharing, i.e.…”

“… 25,26 Several studies have demonstrated the synthesis of niobium based oxide nanosheets, 1,27 nanorods 7,28 and nanospheres 8 through hydro- and solvothermal synthesis. Other approaches, such as colloidal synthesis methods 14 and electrospinning 4 have been reported. However, very little is known on the atomic-scale reaction mechanisms that take place during material synthesis, which hinders rational design of synthesis methods for a given niobium oxide structure.…”

Synthesis and Dual-Mode Electrochromism of Anisotropic Monoclinic Nb12O29 Colloidal Nanoplatelets

“…The preparation of the niobium precursor was varied to control the outcome of synthesis. Pure NPLs are produced using niobium oxo cluster as the precursor while a mixture of mostly orthorhombic Nb2O5 nanorods (NRs), similar to those reported previously, 26 and some NPLs resulted when using niobium chloro oleate. The precursor formation chemistry was investigated, revealing the formation of niobium chloro oleate upon mixing NbCl5 and oleic acid (OA), and that subsequent heating 2 cleaves the Nb-Cl bonds to form niobium oxo cluster.…”