Photocatalyst Activity

The protons/electrons produced in water oxidation at a photoanode side of a PEC device could be used (on the cathode side) to reduce C02 to alcohols/hydrocarbons (CH4, CH30H, HC00H, etc.). In this way, an artificial leaf (photosynthesis) device could be developed [11]. While nanocarbon materials containing iron or other metal particles show interesting properties in this C02 reduction [106], it is beyond the scope of this chapter to discuss this reaction here. It is worthwhile, however, to mention how nanocarbon materials can be critical elements to design both anode and cathode in advanced PEC solar cells. Nanocarbons have also been successfully used for developing photocatalysts active in the reduction of C02 with water [107]. 

Ameen and Raupp examined photocatalytic regeneration following photocatalytic oxidation of o-xylene at 25 ppmv and 80% relative humidity [19]. Exposure to clean flowing air and UV illumination for 12 hr was found to restore the titanium dioxide photocatalyst activity to levels observed with fresh catalysts. 

ATa206 Mg, Ba, Sr Orthorhombic structure used with NiO co-catalyst to enhance photocatalyst activity. 442,451... 

From the studies above, one can observe that the use of Fe has been somewhat limited and that there are still many areas to explore for better utilization of Fe in PC reactions. More specifically, there is a need for the development of new inexpensive techniques or procedures to increase the photocatalyst activity. These new procedures should make the process more efficient without the economic burden that photocatalyst doping brings about. Also, one can notice that most studies have focused on carboxylic acid species containing less than four carbons. It is of utmost importance to explore this area with more refractory molecules such as phenol and other hydroxylated aromatics to determine whether Fe can truly be applied to enhance the PC mineralization. 

The deposition of noble metals (e.g.. Ft, Rh) or metal oxides (e.g., NiO, RUO2) onto photocatalyst surfaces is an effective way of enhancing photocatalyst activity (Sato and White, 1980 Subramanian et al., 2001). The cocatalyst improves the efficiency of photocatalysts, as shovm in Figure 15, as a result of (i) the capture of CB electrons or VB holes from the photocatalysts (Maruthamuthu and Ashokkumar, 1988), thereby reducing the possibility of electron-hole recombination and (ii) the transference... 

It has been known for many years that certain metal oxides promote the photooxidation of aqueous ammonia to produce nitrite ion or, under some conditions, nitrate ion. We have found that catalysts synthesized by methods intended to duplicate those reported for the synthesis of photocatalysts active in the reduction of nitrogen by water are, in fact, catalysts for the... 

A photocatalyst is defined as a substance that is activated by the absorption of a photon and helps accelerate a reaction, without being consumed (Pox, 1988). Factors that influence the photocatalyst activity include structure, particle size, surface properties, preparation, spectral activation, resistance to mechanical stresses. Many of these factors were investigated by Peill and Hoffmann (1995). 

J. Bandara, U. Klehm, J. Kiwi, Raschig rings-Fe203 composite photocatalyst activate in the degradation of 4-chlorophenol and Orange II under daylight irradiation , Apphed Catalysis B Environmental, 76, 73-81, (2007). 

J. Marugan, M. Lopez-Munoz, J. Aguado, R. Grieken, On the comparison of photocatalysts activity A novel procednre for the measnrement of titania snrface in Ti02/Si02 materials . Catalysis Today, 124, 103-109, (2007). 

Doped. One of the most effective ways to develop visible-light-driven photocatalysts is to create impurity levels in the forbidden band through metal ion doping. This makes the wide band gap photocatalysts active in the visible-light region, and this approach has been known for a long time. 

Fillers are typically used to enhance specific properties of polymers, and the polymer/ nanocomposites based on nanoclays have gained attention because of their ability to improve the mechanical, thermal, barrier, and fire-retardant properties of polymers [3]. Nanosized fillers have been introduced in a wide spectrum of applications ranging from providing photocatalyst activation and conductivity to improve melting... 

Formation of a photocatalyst active layer on a porous membrane support by the capillary suction pressure during the dip coating process. (Adapted from Gu and Meng, 1999.)... 

Me H, Kamiya K, Shibanuma T, Miura S, Tryk DA, Yokoyama T, Hashimoto K (2009) Visible light-sensitive Cu(II)-grafted Ti02 photocatalysts activities and x-ray absorption fine structure analyses. J Phys Chem C 113 10761-10766... 

Doping of La2Ti207 with alkaline-earth (Ca, Sr, or Ba) species followed by the deposition of Ag [71] or NiO/Ni [10,72] led to photocatalysts active for CO2 reduction with water as reducing agent [71]. However, the activity reached a... 

Yoneda T., Morimoto T, Hiroya M., Endo E. Coating film having photocatalyst activity and composition forming the coating film. Asahi Glass Co. Ltd., Japanese Published Patent Application No. H9-328336 (1998)... 

TiOj or CdS/ N-CNTs 2.0 Photocatalyst Enhance the photocatalyst activity and modify the intrinsic band gap by the modulation of electronic structures [123,124]... 

Mitoraj D, Kisch H (2008) the nature of nitrogen-modified titanium dioxide photocatalysts active in visible light Angew Chem Int Ed 47(51) 9975-9978... 

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