Synthesis of vacancy-rich titania particles suitable for the additive manufacturing of ceramics

Abstract

In the last decades, titania (or TiO2) particles played a crucial role in the development of photo-catalysis and better environmentally-friendly energy-harvesting techniques. In this work, we engineer a new generation of TiO2 particles rich in oxygen vacancies using a modified sol–gel synthesis. By design, these vacancy-rich particles efficiently absorb visible light to allow carefully-controlled light-induced conversion to the anatase or rutile crystalline phases. FTIR and micro-Raman spectroscopy reveal the formation of oxygen vacancies during conversion and explain this unique laser-assisted crystallization mechanism. We achieve low-energy laser-assisted crystallization in ambient environment using a modified filament 3D printer equipped with a low-power laser printhead. Since the established high-temperature treatment necessary to convert to crystalline TiO2 is ill-suited to additive manufacturing platforms, this work removes a major fundamental hurdle and opens whole new vistas of possibilities towards the additive manufacturing of ceramics, including carefully-engineered crystalline TiO2 substrates with potential applications for new and better photo-catalysis, fuel cells and energy-harvesting technologies.

Photonic post-processing of a multi-material transparent conductive electrode architecture for optoelectronic device integration

“…49 This amorphous precursor is shown to crystallize using 405 or 532 nm laser sources, under environmental conditions. [36][37][38] It is also suitable for photonic postprocessing using a wide-spectrum light source such as a xenon ash lamp. This crystalline TiO 2 layer can be used in the fabrication of optoelectronic devices, whether as the active layer of a photodetector or as an electron transport layer.…”

“…31 There, the metaloxide layer is exposed to UV through shadow-masks in a roll-toroll conguration. Ongoing research on large-area lightinduced sintering & crystallization of metal-oxide materials such as titanium dioxide for optoelectronic devices can be divided into three main areas: UV source-induced, [32][33][34][35] visible and NIR light-induced [36][37][38][39][40] and broadband, pulsed light-induced crystallization. 1,3,12,41,42 Traditionally, most metal oxides are transparent in the visible part of the spectrum, and photonic post-processing requires higher energy than that required to process metallic nanostructures.…”

Deep-learning framework for fully-automated recognition of TiO2 polymorphs based on Raman spectroscopy

“…The presence of surface defects on the crystalline lattice of black anatase shifts the Raman spectrum 56 . This presents an interesting challenge for the model.…”

“…Furthermore, researchers have shown that it is possible to have an enhanced room temperature photo conversion by utilising a defect-rich synthesis of TiO 2 55 . Rapid characterization of TiO 2 polymorphs is crucial for several applications such as additive manufacturing 56 . To test our model using real data from our laboratory, we synthesized standard white anatase, defect rich anatase and rutile TiO 2 , by sol gel chemistry using a protocol described in the literature 57 .…”

“…. Rapid characterization of TiO 2 www.nature.com/scientificreports/ polymorphs is crucial for several applications such as additive manufacturing 56 . To test our model using real data from our laboratory, we synthesized standard white anatase, defect rich anatase and rutile TiO 2 , by sol gel chemistry using a protocol described in the literature 57 .…”