Reversible Photodoping of TiO₂ Nanoparticles for Photochromic Applications

Abstract

Observations on the strong photochromic effect of crystalline TiO 2 quantum dots (mean size ≈ 4 nm) are presented. The synthesized quantum dots consist of irregularly shaped anatase TiO 2 nanoparticles (NPs) and are dispersed in butanol (8% by mass). Obtained NPs exhibit a dramatic photoresponse to UV light, enabling effective transmittance modulation in a broad wavelength range extending from the visible to near-infrared region, and even the thermal black body radiation regime beyond 10 μm. The exceptional photoresponse is attributed to hole-scavenging by butanol, TiO 2 self-reduction, injection of electrons to the conduction band, and consequent localized surface plasmon resonances in NPs. The observed optical effect is reversible, and the initial high transmittance state can be restored simply by exposing the NPs to air. The applied NP synthesis route is economic and can be easily scaled for applications such as smart window technologies.

Natural Polyphenol–Vanadium Oxide Nanozymes for Synergistic Chemodynamic/Photothermal Therapy

“…The other reason is the reduction of V 5+ to V 4+ by TA. The reduction of TA leads to the conversion of V 5+ to V 4+ and a decrease in light transmission, resulting in a visible color change from yellow to black [39] …”

“…[38] The other reasoni st he reduction of V 5 + to V 4 + by TA.T he reduction of TA leads to the conversion of V 5 + to V 4 + and adecrease in light transmission,r esulting in av isible color change from yellow to black. [39] To confirm this hypothesis, control experiments were performed. It is knownt hat the coordination between metal ion and TA is pH-dependent.…”

Facile development of photochromic cellulose acetate transparent nanocomposite film immobilized with lanthanide‐doped pigment: ultraviolet blocking, superhydrophobic, and antimicrobial activity

“…Moreover, photochromism can be employed for military purposes to offer camouflage that is responsive to an external light stimulus. [ 17–19 ]…”

Stronger Reductive Environment in Solvothermal Synthesis Leads to Improved Ga Doping Efficiency in ZnO Nanocrystals and Enhanced Plasmonic Absorption

“…DOSNCs contain relatively large concentration of itinerant electrons (over 10 20 –10 21 cm −3 ) populated in the conduction band, which has been achieved by aliovalent donor doping, electrochemical doping, and photodoping . The donor doping is the most straightforward way and can be achieved by replacing host cations with dopant cations that have a higher oxidation state or host oxygen with nonmetal anions that have a lower oxidation state .…”

“…From these, TiO 2 and ZnO seem to be the most attractive due to their abundance and low toxicity. However, being a transition metal oxide, some electrons are compensated in TiO 2 by changing the oxidation state from Ti 4+ (corresponding to 3d 0 electron configuration) to Ti 3+ (3d 1 ) . This results in a decreased plasmonic absorption in the infrared range, while the impurity levels introduced into the band gap are causing visible light absorption .…”