Dual Use of Copper-Modified TiO2 Nanotube Arrays as Material for Photocatalytic NH3 Degradation and Relative Humidity Sensing

Abstract

In this paper, we emphasized the dual application of Cu-modified vertically aligned TiO2 nanotube arrays as photocatalyst and a relative humidity sensor. The TiO2 nanotube arrays were obtained by anodization of the titanium layer prepared using radio frequency magnetron sputtering (RFMS) and modified with different copper concentrations (0.5, 1, 1.5, and 2 M) by a wet-impregnation method. The sample modified with 2 M Cu(NO3)2 solution showed the highest efficiency for the NH3 photocatalytic degradation and the most pronounced humidity response in comparison to the other studied samples. In order to investigate the structure and impact of Cu modification, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used. The photocatalytic activity and the kinetic study of ammonia oxidation were studied in a mini-photocatalytic wind tunnel reactor (MWPT), while relative humidity sensing was examined by impedance spectroscopy (IS). Higher NH3 oxidation was a direct consequence of the increased generation of •OH radicals obtained by a more efficient photogenerated charge separation, which is correlated with the increase in the DC conductivity.

Al2O3-Based Hollow Fiber Membranes Functionalized by Nitrogen-Doped Titanium Dioxide for Photocatalytic Degradation of Ammonia Gas

“…Titanium dioxide (TiO 2 ) and nitrogen-doped titanium dioxide (N-TiO 2 ) materials have gained prominence as the most researched semiconductor materials for photocatalytic purposes, including their use in devices for photocatalytic degradation of gaseous ammonia under various light sources [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”

“…Recently, Čižmar et al studied the photocatalytic activity of nanostructured Cu-modified vertically aligned TiO 2 nanotube arrays in a mini-photocatalytic wind tunnel reactor (MWPT) [ 11 ].…”

“…However, despite various studies on heterogeneous photocatalytic NH 3 gas degradation through the use of different photocatalytic materials [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ] and relatively few tentative attempts to investigate alternative ways to obtain a compact photocatalytic membrane reactor for indoor pollution abatement [ 11 ], to the best of our knowledge, there has been no case applied to the heterogeneous photocatalytic degradation process using Al 2 O 3 -based hollow fiber membranes functionalized by N-TiO 2 in a novel photocatalytic membrane reactor to completely reduce the NH 3 pollutant concentration.…”

Titania Thin Film Coated Glass for Simultaneous Ammonia Degradation and UV Light Blocking Layer in Photovoltaics

“…The NH 3 degradation over TiO 2 -based photocatalysts has been thoroughly investigated [18][19][20][21][22]. Complimentary to the generally accepted oxidation pathway initialised by • OH radicals, Yuzawa et al [21] proposed a tentative reaction pathway for NH 3 degradation over TiO 2 loaded with metal co-catalysts.…”

“…Disregarding the dominant degradation pathway, the role of incident irradiation and photocatalyst optical properties play a crucial role in terms of NH 3 degradation efficiency. Therefore, any intervention into photocatalysts surface morphology that will change the absorption and scattering coefficients should be thoroughly studied [20].…”