TiO2 Nanostructured Films for Electrochromic Paper Based-Devices

Abstract

Electrochromic titanium dioxide (TiO2) nanostructured films were grown on gold coated papers using a microwave-assisted hydrothermal method at low temperature (80 °C). Uniform nanostructured films fully covered the paper substrate, while maintaining its flexibility. Three acids, i.e., acetic, hydrochloric and nitric acids, were tested during syntheses, which determined the final structure of the produced films, and consequently their electrochromic behavior. The structural characteristics of nanostructured films were correlated with electrochemical response and reflectance modulation when immersed in 1 M LiClO4-PC (lithium perchlorate with propylene carbonate) electrolyte, nevertheless the material synthesized with nitric acid resulted in highly porous anatase films with enhanced electrochromic performance. The TiO2 films revealed a notable contrast behavior, reaching for the nitric-based film optical modulations of 57%, 9% and 22% between colored and bleached states, at 250, 550 and 850 nm, respectively in reflectance mode. High cycling stability was also obtained performing up to 1500 cycles without significant loss of the electrochromic behavior for the nitric acid material. The approach developed in this work proves the high stability and durability of such devices, together with the use of paper as substrate that aggregates the environmentally friendly, lightweight, flexibility and recyclability characters of the substrate to the microwave synthesis features, i.e., simplicity, celerity and enhanced efficiency/cost balance.

Titanium Dioxide in Chromogenic Devices: Synthesis, Toxicological Issues, and Fabrication Methods

“…This has disclosed unexpected, emerging properties of the materials due to shape and size, affecting interfacial behavior as well as phonon and photon transport, and inverting the surface-to-volume ratio, as reported previously in this work [88,157,158]. Different crystal structures have been reported for TiO 2 , such as anatase [159], brookite [160,161], and rutile [162,163]. In each of them, a TiO 6 octahedron contains Ti 4+ ions, surrounded by six O 2− atoms.…”

Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation

“…Cellulose-based materials have been employed in distinct applications, including optoelectronic devices, such as solar cells and transistors [7,9,10], sensors [11][12][13][14], electrochromic devices [15,16], but also in diagnostic platforms [17,18] and photocatalysis [12,19,20]. In terms of photocatalysis, despite all the envisioned applications of paper-based materials, its implementation is not straightforward.…”

“…TiO2 thin films have been also largely investigated [157][158][159]. Various techniques have been reported for producing TiO2 nanostructures or thin films including wet-chemical techniques [160,161], the sol-gel method [84,158], thermal evaporation [162], magnetron sputtering [163,164], anodization [165,166], electrodeposition [167,168], the gas jet fiber spinning process [103], electrospinning [104,169], hydrothermal and solvothermal synthesis [170][171][172][173], and microwave irradiation [15,36,38], among several other methods. [38], (c) TiO2 nanobelts [174], (d) TiO2 nanorods aggregated to form micro-sized spheres [37], (e) TiO2 nanotubes formed by anodization [175], (f) TiO2 nanowires [176], (g-i) different types of TiO2 nanoflowers [155], and (j) TiO2 nanospheres [156].…”

“…The integration of TiO 2 in cellulose-based materials to form composites or membranes has been reported, but the growth or deposition of thin films or nanostructures on a paper substrate has also shown promise [12,15,19,177,178]. Hu et al [179] produced a flexible and binder-free graphene-TiO 2 paper to be applied as lithium-ion battery anode materials, consisting of 3-D nano-structures with nano-sized TiO 2 intercalated between graphene layers as pillars to increase the Li-ion insertion/extraction rate.…”

Transduction Mechanisms, Micro-Structuring Techniques, and Applications of Electronic Skin Pressure Sensors: A Review of Recent Advances

“…Therefore, this review summarizes in one place comprehensive and vital aspects of pressure sensors, namely transduction mechanisms, micro-structuring techniques, most employed materials, and applications, that are typically not found together in other reviews. Regarding other types of interesting sensors and devices, such as strain sensors, humidity sensors, temperature sensors, biosensors, chemical sensors, gas sensors, antennas, energy harvesters, amongst others, many reviews are available for consulting [ 3 , 4 , 5 , 34 , 48 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ].…”