Preparation of Visible Light Photocatalytic Graphene Embedded Rutile Titanium(IV) Oxide Composite Nanowires and Enhanced NOx Removal

Abstract

The quest for developing highly efficient TiO2-based photocatalysts is continuing and, inparticular, evolving a new strategy is an important aspect in this regard. In general, much effort hasbeen devoted to the anatase TiO2 modifications, despite there being only a few recent studies onrutile TiO2 (rTiO2). To the best of our knowledge, studies on the preparation and characterization ofthe photocatalysts based on the intentional inclusion of graphene (G) into rTiO2 nanostructureshave not been reported yet. Herein, we develop a new type of TiO2-based photocatalyst comprisingof G included pure rTiO2 nanowire (abbreviated as rTiO2(G) NW) with enhanced visible lightabsorption capability. To prepare rTiO2(G) NW, the G incorporated titanate electrospun fibers wereobtained by electrospinning and subsequently heat treated at various temperatures (500 to 800 °C).Electrospinning conditions were optimized for producing good quality rTiO2(G) NW. The rTiO2(G)NW and their corresponding samples were characterized by appropriate techniques such as X-raydiffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopyand UV-vis diffuse reflectance spectroscopy to ascertain their material characteristics. XRD resultsshow that the lattice strain occurs upon inclusion of G. We present here the first observation of anapparent bandgap lowering because of the G inclusion into TiO2 NW. While anatase TiO2 NWexhibited poor visible light photocatalysis towards NOx removal, the rTiO2(G) NW photocatalystwitnessed a significantly enhanced (~67%) photocatalytic performance as compared to anataseTiO2(G) NW. We concluded that the inclusion of G into rTiO2 nanostructures enhances the visiblelight photoactivity. A plausible mechanism for photocatalysis is suggested.

Manganese and Graphene Included Titanium Dioxide Composite Nanowires: Fabrication, Characterization and Enhanced Photocatalytic Activities

“…It is interesting to inform that there are no reflection peaks that correspond to manganese phases in the XRD patterns, even with the highest doping concentration ( Table 1). It must be noted that characterization results of the following samples prepared under similar experimental conditions were already reported in our earlier work [24] and hence are not presented here. The percentage (%) of anatase and rutile phases in the samples was calculated and presented in Table 1.…”

“…The two major steps involved in the synthesis include (i) preparation of G included TiO 2 composites (titanate NWs) and (ii) calcination. The detailed preparation procedures of G-incorporated composite titanate nanofibers can be referred from our earlier reports published elsewhere [24][25][26][27]. A similar route has been adopted for the synthesis of Mn-embedded composite titanate NWs.…”

“…The prominent synthetic methods of TiO 2 NW include sol-gel, hydrothermal and electrospinning. Among the various methods for the preparation of TiO 2 NW, electrospinning is versatile and an up-scalable technique [24][25][26][27][28].…”

“…Non-metal (carbon, nitrogen, sulphur) doping has been extensively studied, especially after the work by Asahi et al [34] on nitrogen-doped TiO 2 [34,35]. The composites or hybrids of TiO 2 with either graphene oxide [36], reduced graphene oxide, exfoliated graphene (G) sheets or G sheets having oxygenous functional groups (such as carboxylic (-COOH), hydroxyl (-OH) and carbonyl (C=O) groups) on the surface were effectively used to enhance the photocatalytic ability of TiO 2 [24,[37][38][39][40][41]. Through various studies, its understood that G inclusion into TiO 2 improves the photocatalytic efficiency of TiO 2 owing to its large specific surface area that can facilitate the distribution of TiO 2 and enable narrowing of the band gaps of TiO 2 [24][25][26][27][28]41,42].…”

Facile Fabrication of Metal Oxide Based Catalytic Electrodes by AC Plasma Deposition and Electrochemical Detection of Hydrogen Peroxide

“…Non-enzymatic electrochemical H 2 O 2 sensors are designed based on H 2 O 2 electro-oxidation/electroreduction and thus require electrocatalytic materials. Therefore, development of new electrode materials with high catalytic activity and catalytic stability is continuously being given priority and utmost importance.Several metal oxide nanostructures [11][12][13][14][15][16][17] have been utilized to modify the surface of electrodes and were demonstrated to exhibit excellent redox capabilities towards detection of H 2 O 2 with high reaction activity, catalytic efficiency, strong absorption ability, and low cost [18,19]. Particularly, copper oxide (CuO) has been extensively used in non-enzymatic electrochemical sensors, due to its excellent electrochemical properties (proper redox potentials), catalytic properties (enhanced reaction rate, weak adsorption of hydrogen species etc.…”