Reactive Magnetron Sputter Deposition of Copper on TiO<inf>2</inf> Support for Photoreduction of CO<inf>2</inf> to CH<inf>4</inf>

© Published under licence by IOP Publishing Ltd. In this work, nanocrystalline Cu/TiO2 catalysts have been synthesized by using pulsed direct current (DC) reactive magnetron sputtering of Cu targets in an Ar atmosphere onto P25-TiO2 support. The oscillating bowl was used to make the uniform coating on the substrate. The Cu doping content was varied by adjusting the coating time. The thus-obtained catalysts were characterized by using the X-ray diffraction (XRD), UV-Vis spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The photocatalytic activities of all catalysts were studied via the photocatalytic reduction of CO2 and H2O to CH4 under UV irradiation, and compared with the pure TiO2 support and conventional-impregnation-made Cu/TiO2. The results showed that the photocatalytic performance of sputtering-made Cu/TiO2 catalyst was much better than the pure TiO2 support. Therefore, reactive magnetron sputtering was a promising technique for deposition of metal onto the support and use as the catalytic process

Visible light active photocatalytic C-doped titanium dioxide films deposited via reactive pulsed DC magnetron co-sputtering: Properties and photocatalytic activity

Doping of TiO2 with carbon is known to be an efficient method of enhancing visible light photocatalytic activity. The present work describes the deposition of carbon-doped titania coatings deposited by reactive magnetron co-sputtering of Ti and C targets. Undoped titania coatings were produced under similar deposition conditions for comparison purposes. Following deposition, all coatings were annealed in air at 873 K for 30 min to develop the required crystalline structure; and then analysed with EDS, XRD, AFM, XPS and UVevisible spectrophotometry. A number of tests, including methylene blue and stearic acid decomposition tests, and photo-induced hydrophilicity measurements, were employed for the assessment of the photocatalytic properties of the C-doped and un-doped titanium dioxide coatings under UV and visible light irradiation. It was found that carbon-doped titania coatings significantly outperformed undoped titania when using both visible and UV irradiation. Similar trends were observed for other properties. While excessive carbon doping has been shown to have a negative effect on the photocatalytic properties of the titanium dioxide, overall, carbon doping via reactive co-sputtering has been confirmed as an efficient method of photocatalytic property enhancement. This is due to a narrowing of the bandgap and to extended lifetimes of the photo-generated charge carriers

Deposition of Visible Light-Active C-Doped Titania Films via Magnetron Sputtering Using CO2 as a Source of Carbon

Doping of titanium dioxide with p-block elements is typically described as an efficient pathway for the enhancement of photocatalytic activity. However, the properties of the doped titania films depend greatly on the production method, source of doping, type of substrate, etc. The present work describes the use of pulsed direct current (pDC) magnetron sputtering for the deposition of carbon-doped titania coatings, using CO2 as the source of carbon; ratios of O2/CO2 were varied through variations of CO2 flow rates and oxygen flow control setpoints. Additionally, undoped Titanium dioxide (TiO2) coatings were prepared under identical deposition conditions for comparison purposes. Coatings were post-deposition annealed at 873 K and analysed with scanning electron microscopy (SEM), X-ray diffreaction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic properties of the thin films were evaluated under ultraviolet (UV) and visible light irradiation using methylene blue and stearic acid decomposition tests. Photoinduced hydrophilicity was assessed through measurements of the water contact angle under UV and visible light irradiation. It was found that, though C-doping resulted in improved dye degradation compared to undoped TiO2, the UV-induced photoactivity of Carbon-doped (C-doped) photocatalysts was lower for both model pollutants used

Formation and growth characteristics of nanostructured carbon films on nascent Ag clusters during room-temperature electrochemical CO2 reduction

Synthesis of carbon nanostructures at room temperature and under atmospheric pressure is challenging but it can provide significant impact on the development of many future advanced technologies. Here, the formation and growth characteristics of nanostructured carbon films on nascent Ag clusters during room-temperature electrochemical CO(2) reduction reactions (CO(2)RR) are demonstrated. Under a ternary electrolyte system containing [BMIm](+)[BF(4)](−), propylene carbonate, and water, a mixture of sp(2)/sp(3) carbon allotropes were grown on the facets of Ag nanocrystals as building blocks. We show that (i) upon sufficient energy supplied by an electric field, (ii) the presence of negatively charged nascent Ag clusters, and (iii) as a function of how far the C–C coupling reaction of CO(2)RR (10–390 min) has advanced, the growth of nanostructured carbon can be divided into three stages: Stage 1: sp(3)-rich carbon and diamond seed formation; stage 2: diamond growth and diamond–graphite transformation; and stage 3: amorphous carbon formation. The conversion of CO(2) and high selectivity for the solid carbon products (>95%) were maintained during the full CO(2)RR reaction length of 390 min. The results enable further design of the room-temperature production of nanostructured carbon allotropes and/or the corresponding metal-composites by a viable negative CO(2) emission technology

Synthesis of Cu/TiO2 catalysts by reactive magnetron sputtering deposition and its application for photocatalytic reduction of CO2 and H2O to CH4

© 2019 In the present work, a series of Cu/TiO2 catalysts were successfully synthesized by using pulsed direct current (DC) reactive magnetron sputtering of Cu targets under Ar atmosphere onto various TiO2 supports. The physiochemical properties of the catalysts were characterized by using inductive coupled plasma spectroscopy (ICP), X-ray diffraction (XRD), UV–Vis spectroscopy, N2 physisorption, transmission electron microscopy (TEM), PL spectroscopy, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of all the catalysts were studied via the photocatalytic reduction of CO2 and H2O to CH4 under UV light irradiation. The Cu/TiO2 catalysts exhibited higher photocatalytic activity than the uncoated TiO2 supports and the ones made using an impregnation technique. The electron trapping of copper species, which prolonged the electron-hole recombination process, promoted photocatalytic activity of the Cu-doped catalysts. Moreover, the specific morphologies of the Cu species deposited on TiO2 supports and the smaller change of bandgap energy of the sputter coated catalysts also resulted in an improvement of photocatalytic activity under UV light irradiation

Catalytic Activity During Copolymerization of Ethylene and 1-Hexene via Mixed TiO2/SiO2-Supported MAO with rac-Et[Ind]2ZrCl2 Metallocene Catalyst

Activities during ethylene/1-hexene copolymerization were found to increaseusing the mixed titania/silica-supported MAO with rac-Et[Ind]2ZrCl2 metallocenecatalyst. Energy Dispersive X-ray spectorcopy (EDX) indicated that the titania wasapparently located on the outer surface of silica and acted as a spacer to anchor MAO tothe silica surface. IR spectra revealed the Si-O-Ti stretching at 980 cm-1 with low contentof titania. The presence of anchored titania resulted in less steric hindrance and lessinteraction due to supporting effect