Top-down surfactant-free electrosynthesis of magnéli phase Ti9O17 nanowires

Abstract

TiO₂ nanowires have proven their importance as a versatile material in numerous fields of technology due to their unique properties attributable to their high aspect ratio and large surface area. However, synthesis is an enormous challenge since state-of-the-art techniques rely on complex, multi-stage procedures with expensive, specialized equipment, employing high-temperature steps and potentially toxic precursor materials and surfactants. Hence, we elucidate a simple and facile top-down methodology for the synthesis of nanowires with non-stoichiometric Magnéli phase Ti₉O₁₇. This methodology relies on the electrochemical erosion of bulk Ti wires immersed in an aqueous electrolyte, circumventing the use of environmentally harmful precursors or surfactants, eliminating the need for high temperatures, and reducing synthesis complexity and time. Using multiple techniques, including transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, we provide evidence of the successful synthesis of ultrathin nanowires with the crystal structure of non-stoichiometric Ti₉O₁₇ Magnéli phase. The nanowire width of ∼5 nm and the Brunauer–Emmett–Teller surface area of ∼215 m² g⁻¹ make the nanowires presented in this work comparable to those synthesized by state-of-the-art bottom-up techniques.