Layer‐by‐Layer Deposited Titanate‐Based Nanotubes for Solar Photocatalytic Removal of Chemical Warfare Agents from Textiles

Abstract

Since the discovery of carbon nanotubes by Iijima, [1] extensive research on the synthesis of nanotubes made of materials other than carbon, and especially of oxides such as MoO 3 , WO 3 , VO x , and TiO 2 has been reported. [2] In recent years, TiO 2 and materials derived from TiO 2 have been the focus of numerous investigations for applications in photovoltaic cells, [3] gas sensors, ultraviolet blockers, and for promising applications in photocatalysis. Moreover, nanoscale onedimensional TiO 2 materials have recently attracted much attention, [4] as they offer a larger surface area available in comparison to nanoparticles and also provide channels for enhanced electron transfer.[4] The nanotubes have high adsorption capacity, and efficient charge separation can be achieved on their surfaces, which reduces the recombination of photogenerated electrons and holes [5] that play determing roles in photocatalytic reactions.The threat from chemical warfare agents (CWAs) has evolved over the past century. Attacks both on the battlefield and in civilian areas have demonstrated the high occurrence of casualties and thus the need for efficient protection. Therefore, post-use decontamination procedures on exposed and contaminated materials are much required. The current methods investigated are incineration, destruction, and neutralization using various chemicals, adsorption of the contaminants by an adsorbant, and the use of impermeable membranes. All of these methods present significant drawbacks as they cannot be directly applied on the battlefield, or these methods do not lead to the destruction of the toxic agents, but rather the adsorption of or a skin barrier to the contaminants.The photocatalytic activity of TiO 2 has been widely studied ever since its photoactivity was discovered in 1972 by Fujishima and Honda.[6] The development of high aspect ratio TiO 2 nanostructures with high efficiency for solar photocatalytic applications is one of the biggest challenges concerning this material. Herein, we report the first use of coupled WO 3 /titanate nanotubes for efficient degradation of simulants and real chemical warfare agents (blistering and nerve agents) under solar illumination. Efficient performance of the titanate nanotubes (TiNTs) for direct degradation of gas-phase agents has been observed. Furthermore, a layer-bylayer (LbL) deposition of TiNTs on textiles can provide additional protection against percutaneous exposure to toxic liquids, vapors, and aerosols. Figure 1 and Figure 2 show transmission electron microscope (TEM) images of the one-dimensional WO 3 /TiNTs at different steps of its synthesis. The titanate (Figure 1 a) was first obtained as an aligned nanosheet, which upon washing with HCl until neutralization and drying at 110 8C led to openended TiNT tubes (Figure 1 b)with lengths of several tens or hundreds of nm and diameters around 15 nm and with a multilayered wall thickness of less than 2 nm. This is in agreement with the results reported in the literature. [7] As the temperature was increased...

Photocatalytically Active Polyelectrolyte/Nanoparticle Films for the Elimination of a Model Odorous Gas

“…The past years have brought an increasing number of applications of layer-by-layer (LbL) assembly (e.g., [1,2] ) in a large variety of different fields (e.g., [3][4][5][6][7][8][9][10][11][12][13] ) including catalysis (e.g., [14][15][16][17][18][19][20][21][22][23][24] ), but materials and devices based on large-area LbL-coatings are still scarce. Photocatalytic applications are an especially promising area for LbLassembly because multilayer films are often transparent, because of the large choice of catalytical components that can be used for their construction and because of the ease by which even porous materials and surfaces such as membranes, textiles, and paper can be coated fairly well from aqueous solutions or dispersions.…”

Preparation and Microstructure of Titanate Nanotube Thin Films by Spray Layer-by-Layer Assembly Method

“…Note that this spray LbL conditions were suitable for the thin-film processing of TiO 2 anatase nanoparticles and titanate nanowires [11]. It is also worthy of note that the conventional LbL (by alternate immersion for 20 min) was already efficiently used for covering titanate nanotubes over textiles [14].…”

Spray‐Assisted Polyelectrolyte Multilayer Buildup: from Step‐by‐Step to Single‐Step Polyelectrolyte Film Constructions

“…To improve the photocatalytic activity of the nanoparticles, Grandcolas et al developed titanate nanotubes (TiNT) impregnated with WO 3 . [79] The absorbance of these WO 3 /TiNT nanotubes extended far in the visible range compared to bare TiNT nanotubes. These nanotubes were incorporated into poly(ethyleneimine)/TiNT multilayers obtained by alternate spraying of TiNT and PEI solutions onto textiles.…”