Optimized Nanostructured TiO2 Photocatalysts

Abstract

Titania is the most widely studied photocatalyst. In its mixed-phase configuration ( anatase-rutile form) -as manifested in the commercially available P25 Degussa materialtitania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field has not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypotheses in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or "catalytic 'hot-spots'." Therefore, non-woven nanofibrous mats of titania were produced, and upon calcination, the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples, the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500°C with an anatase/rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.

Carbon Domains on MoS2/TiO2 System via Catalytic Acetylene Oligomerization: Synthesis, Structure, and Surface Properties

“…Besides nanocarbons, prominent candidates for heterostructures and hybrid combinations belong to the family of semiconducting inorganic systems, such as nanostructured transition metal dichalcogenides (TMDs, i.e., MoS 2 , WS 2 ) and oxides (i.e., TiO 2 , perovskites) (Rijnders, 2014 ; Duan et al, 2015 ). For instance, titanium dioxide polymorphs are by far the best candidates in some fields, offering an ideal platform for photocatalytic and catalytic applications (Cesano et al, 2012a ; Topcu et al, 2016 ), but they have a relatively large bandgap (about 3–3.2 eV). Notwithstanding, feasible strategies may be adopted in harvesting the visible solar light.…”

2D/2D Graphitic Carbon Nitride (g-C3N4) Heterojunction Nanocomposites for Photocatalysis: Why Does Face-to-Face Interface Matter?

“…By harvesting solar energy as the source of renewable energy, photocatalysis will make significant impacts in the areas of (1) light-driven water splitting to hydrogen (H2) and oxygen (O2) (Chen et al, 2010;Bai et al, 2016;Wei et al, 2016;Putri et al, 2017;Yubin et al, 2017), (2) conversion of carbon dioxide (CO2) to energy bearing fuels (Ong et al, , 2014cTan et al, 2014Tan et al, , 2016Tan et al, , 2017Gui et al, 2015;Guo et al, 2016a;Zhang et al, 2016c), (3) mineralization of waste and pollutants (Ong et al, 2014d,e;Fang et al, 2016;Liu et al, 2016c;Topcu et al, 2016;Zhao et al, 2016b), (4) selective organic transformations (Liu et al, 2014;Zhao et al, 2016a), and (5) disinfection of bacteria (Keane et al, 2014;Bing et al, 2015) (Figure 1). Very recently, two-dimensional (2D) semiconductor photocatalysts have triggered a renaissance of interest in the field of energy, and environmental-related applications thank to the high ratio of surface-to-volume and unprecedented electronic and optical characteristics (Ong et al, 2014b;Bai et al, 2015;Liang et al, 2015d;Fang et al, 2016;Kalantar-zadeh et al, 2016;She et al, 2017;Xueting et al, 2017).…”

1D Titanium Dioxide: Achievements in Chemical Sensing

“…Recently, MOXs such as zinc oxide (ZnO) [ 14 ], nickel oxide (NiO) [ 15 ], titanium dioxide (TiO 2 ) [ 12 ] and tungsten oxide (WO 3 ) [ 11 ] have been grown in the form of 1D nanostructures and were used for the detection of different gas analytes. Among these MOXs, TiO 2 is one of the most versatile ones and is widely used for many different applications, including photocatalysis [ 16 ], sensors [ 17 , 18 ] and photovoltaic applications [ 19 ]. In particular, due to its exceptional physical/chemical properties, TiO 2 was extensively used for different sensing applications such as chemical/gas sensors [ 20 , 21 ], biosensors [ 17 , 22 ] and chemical oxygen demand (COD) [ 23 , 24 ] sensors [ 25 ].…”