The nature of the photochromism arising in the nanosized MoO3 films

An ultraselective and ultrasensitive TEA sensor based on α-MoO3 hierarchical nanostructures and the sensing mechanism

“…And from the high-magnification SEM image ( Fig. 1b and c), it is 15 clearly observed that numerous nanobelts with sharp tips and rough rims linked to one center are 20-30 nm in thickness. These high-density nanobelts are radially assembled into flower-like shape, which is named as the flower-like hierarchical nanostructures.…”

“…Obviously, the responses of these three morphologies of α-MoO 3 to 10 ppm TEA at 170-290 °C present the same variation trend with the working temperature increasing, that is, the responses of 10 these sensors to TEA decrease with working temperature increasing from 170 to 290 °C, which might be attributed to the characteristics of the sensing materials and adsorption/desorption quantities of TEA molecules on the surface of α-MoO 3 . When the α-MoO 3 sensor is exposed to 10 ppm TEA gas at 170 °C, more 15 TEA gas molecules are adsorbed on the α-MoO 3 surface and oxidized, indicating high activity of the reaction at the relatively low working temperature of 170 °C. However, with the temperature increasing, more and more TEA molecules are much easier to be desorbed from MoO 3 surface, leading to the effective 20 adsorption quantities of TEA decrease.…”

“…[2][3][4][5][6] But the defect of poor selectivity limits their practical application under complex surrounding conditions. As one of the most significant functional materials, MoO 3 is an environmentally friendly n-type semiconductor material (E g = 3.1 35 eV), which has attracted considerable attention in the field of photocatalysts, 7,8 gas sensors, 9,10 electrochemistry, 11,12 field emission, 13 gaschromic 14 and photochromic devices 15 due to its special quantum size effect, surface effect and high reactivity characteristics. Among three basic polymorphs of MoO 3 ,40 orthorhombic MoO 3 (α-MoO 3 ) has good thermal stability, and the unique layered crystal structure is favorable for gases to diffuse, thus, α-MoO 3 is a kind of promising candidate for gas sensor.…”

“…[36][37][38][39][40][41] Most of the above processes are usually complicated or need surfactants and templates, which 10 have to undergo complex removal procedures. Moreover, the present works so far mainly focus on the fundamental research of synthesis methods and formation process, while the properties, especially the gas sensing performance and related sensing mechanism of the hierarchical α-MoO 3 nanostructures have rarely 15 been reported. A solvothermal route combined with subsequent calcination in air was realized as an effective approach to prepare hierarchical MoO 3 flowers just recently, 42 the building-blocks of which were polycrystalline microrods.…”

Smart Window Technologies: Electrochromics and Nanocellulose thin film Membranes and Devices

“…Resulting in deeper coloration due to increased charge transfer; while also, the device may degrade especially due to formation of excess polymeric components for consistent resonant tunneling effects [14][15][16][17][18][19][20]. The EC devices have open circuit memory, and can function without energy for long periods; optical absorption can be tuned between states, but the optical change is slow depending on device size varying from seconds to tens of minutes [3].…”