Effect of Thermal Treatment of Symmetric TiO2 Nanotube Arrays in Argon on Photocatalytic CO2 Conversion

Abstract

Symmetric titania nanotube arrays (TiO2 NTs) are a well-known photocatalyst with a large surface area and band edge potentials suitable for redox reactions. Thermal treatment of symmetrical arrays of TiO2 nanotubes in argon was used to change the carbon content of the samples. The influence of the carbon content in the structure of symmetrical TiO2 NTs on their photoelectrochemical properties and photocatalytic activity in the conversion of CO2 into organic fuel precursors has been studied. The structure, chemical, and phase composition of obtained samples were studied by X-ray analysis, Raman spectroscopy, and SEM with energy dispersive analysis. It is established that carbon-related defects in the samples accumulate electrons on the surface required for the CO2 conversion reaction. It has been shown for the first time that varying the carbon content in symmetric TiO2 NTs arrays by annealing at different temperatures in argon makes it possible to control the yield of methane and methanol in CO2 conversion. It is revealed that too high a concentration of carbon dangling bonds promotes the growth of CO2 conversion efficiency but causes instability in this process. The obtained results show a high promise of symmetric carbon-doped TiO2 NTs arrays for the photocatalytic conversion of CO2.

Asymmetry of Structural and Electrophysical Properties of Symmetrical Titania Nanotubes as a Result of Modification with Barium Titanate

“…For a long time, titania (TiO 2 ) has remained the object of intensive scientific research devoted to the development of new methods for the synthesis of the material in various structural forms, including monophasic structures and nanostructures, as well as nanocomposites [8][9][10][11][12]. The attractiveness of nanostructured TiO 2 for researchers in recent decades is due to its significant specific surface area [8][9][10][11][12].…”

“…For a long time, titania (TiO 2 ) has remained the object of intensive scientific research devoted to the development of new methods for the synthesis of the material in various structural forms, including monophasic structures and nanostructures, as well as nanocomposites [8][9][10][11][12]. The attractiveness of nanostructured TiO 2 for researchers in recent decades is due to its significant specific surface area [8][9][10][11][12]. The wide and varied range of applications of nanocrystalline TiO 2 includes use in solar cells, in gas sensors, as a photoanode for photoinduced water decomposition, in the food and pharmaceutical industries, in optoelectronics and memristors due to its chemical resistance, suitable band edge potentials and propensity to form oxygen vacancies in its structure [8][9][10][11][12].…”

“…The attractiveness of nanostructured TiO 2 for researchers in recent decades is due to its significant specific surface area [8][9][10][11][12]. The wide and varied range of applications of nanocrystalline TiO 2 includes use in solar cells, in gas sensors, as a photoanode for photoinduced water decomposition, in the food and pharmaceutical industries, in optoelectronics and memristors due to its chemical resistance, suitable band edge potentials and propensity to form oxygen vacancies in its structure [8][9][10][11][12]. It is used for the photocatalytic purification of air and water, as well as for the photocatalytic conversion of carbon dioxide into more complex carbon compounds and other energy-intensive processes [9,[12][13][14].…”

“…The wide and varied range of applications of nanocrystalline TiO 2 includes use in solar cells, in gas sensors, as a photoanode for photoinduced water decomposition, in the food and pharmaceutical industries, in optoelectronics and memristors due to its chemical resistance, suitable band edge potentials and propensity to form oxygen vacancies in its structure [8][9][10][11][12]. It is used for the photocatalytic purification of air and water, as well as for the photocatalytic conversion of carbon dioxide into more complex carbon compounds and other energy-intensive processes [9,[12][13][14]. Researchers were able to compensate for the major drawback of TiO 2 's wide bandgap and ultraviolet light requirement by introducing impurities and/or defects into its structure [12][13][14][15][16][17].…”

“…It is used for the photocatalytic purification of air and water, as well as for the photocatalytic conversion of carbon dioxide into more complex carbon compounds and other energy-intensive processes [9,[12][13][14]. Researchers were able to compensate for the major drawback of TiO 2 's wide bandgap and ultraviolet light requirement by introducing impurities and/or defects into its structure [12][13][14][15][16][17]. Impurity centers successfully "reduce" the band gap of TiO 2 by locating energy levels inside it and providing photon absorption using these energy levels [12,[14][15][16][17][18].…”