scholarly journals Recent Advancements in the Understanding of the Surface Chemistry in TiO2 Photocatalysis

Surfaces ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 72-92 ◽  
Author(s):  
Alexander V. Vorontsov ◽  
Héctor Valdés ◽  
Panagiotis G. Smirniotis ◽  
Yaron Paz

Surface chemistry plays a major role in photocatalytic and photoelectrochemical processes taking place with the participation of TiO2. The synthesis methods, surface characterizations, theoretical research methods, and hardware over the last decade generated opportunities for progress in the surface science of this photocatalyst. Very recently, attention was paid to the design of photocatalysts at the nanoscale level by adjusting the types of exposed surfaces and their ratio, the composition and the surface structure of nanoparticles, and that of individual surfaces. The current theoretical methods provide highly detailed designs that can be embodied experimentally. The present review article describes the progress in the surface science of TiO2 and TiO2-based photocatalysts obtained over the last three years. Such aspects including the properties of macro- and nano-scale surfaces, noble-metal-loaded surfaces, doping with Mg and S, intrinsic defects (oxygen vacancies), adsorption, and photoreactions are considered. The main focus of the article is on the anatase phase of TiO2.

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1009
Author(s):  
Suresh Thangudu ◽  
Mu Tzu Lee ◽  
Sami Rtimi

Molybdenum Sulfide nanosheets (MoS2 NSs) have unique properties that allow its use in a wide range of applications. Unfortunately, a lack of green synthesis methods to achieve a high yield remains a challenge after decades. Herein we report a simple, ecofriendly, green and cost-effective approach to synthesize water soluble MoS2 NSs via probe/Tip sonication method. The sequential batch manner pathway allows us to attain a high yield of MoS2 NSs (~100%). The prepared MoS2 NSs were characterized using up-to-date surface science techniques. UV-visible-NIR spectroscopy allowed us to visualize the doublet peaks of pristine MoS2 at 610 and 680 nm concomitant with the inter-band transitions at 394 nm and 460 nm. Using Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS), the crystallites’ sizes were estimated. X-ray diffraction (XRD) and Raman Spectroscopy were performed with respect to the bulk MoS2. The energy difference between the Raman peaks revealed that our NSs are formed of 5–6 layers. Further, we explored enzyme peroxidase mimetic properties of the synthesized MoS2 NSs. Results showed that the present MoS2 NSs offer excellent peroxidase mimicking properties. Most importantly, we observed that the optical properties and characteristics of MoS2 NSs synthesized by the current green method are similar to those of MoS2 NSs synthesized using conventional harsh methods reported in the literature. So that we strongly assume that the present method is a green alternative for the existing low yield and harsh experimental procedures to achieve water soluble MoS2 NSs in high yield. The synthesized soluble NSs are promising catalysts for the detection of toxic chemicals in the environment and/or for following enzymatic chromogenic reactions.


2017 ◽  
Vol 17 ◽  
pp. 127-130
Author(s):  
J. Dhanalakshmi ◽  
D. Pathinettam Padiyan

Dy2O3-TiO2 nanocomposites with different weight percentage (0, 2, 4, 8 & 10)Dy were synthesized bysol-gel method and named as 0DT, 2DT, 4DT, 6DT, 8DT and 10DT. The structural properties of these nanocomposites are characterized by X-ray diffraction (XRD) and Raman spectroscopy. XRD results show that Dy2O3-TiO2 nanocomposites have anatase phase with tetragonal structure. The average crystallite size of the Dy2O3-TiO2 nanocomposites lies between 10 to 18 nm.Coupling of Dy with TiO2 shifts the Raman band to higher wavenumber side indicating the creation of oxygen vacancies in the TiO2 lattice.


Author(s):  
Vignesh Kumaeavel ◽  
Stephen Rhatigan ◽  
Snehamol Mathew ◽  
Marie Clara Michel ◽  
John Bartlett ◽  
...  

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