Photocatalytic degradation of orange II on the novel hetero-system WS2/TiO2 under UV light

Abstract

The photodegradation of orange II (OII) is successfully achieved on the new hetero-system WS 2 /TiO 2 under UV illumination. The nano sized bi-functional catalyst is prepared by sol gel and calcined at *450°C. The X-ray diffraction shows noticeably broad peaks and TiO 2 is therefore less crystallized with the anatase phase. The sensitizer WS 2 presents a direct optical transition at 1.72 eV. The Mott-Schottky plot (C -2 -V) is characteristic of n type conduction from which a flat band potential of 0.17 V SCE and a donor density of 5.30 9 10 17 cm -3 are determined. An energy band diagram is established, predicting an electron transfer from WS 2 to TiO 2 ; the injection process is confirmed by the photocurrent measurements at different concentrations. Upon increasing the mass of WS 2 , the activity increases and the best performance occurs on 30 % WS 2 /TiO 2 . A conversion of 98 % is reported in aerated solution for OII concentration of 10 ppm in less than 90 min. The oxidation follows a first order kinetic with a rate constant of 4.8 9 10 -2 min -1 .

Au plasmonics in a WS2-Au-CuInS2 photocatalyst for significantly enhanced hydrogen generation

“…13 In category of TMDs, WS 2 is an attractive material for the solar energy conversion because it combines a narrow band gap and a chemical inertness over a fair pH range. [14][15][16][17] In line with this, we have recently achieved WS 2 nanotubes (NTs) and controllably derived WS 2(1Àx) Se 2x NTs on flexible and conductive carbon fiber (CF) substrate. 18 Additionally, owing to its high absorption coefficient and ideal band gap ($1.4 eV), 19 copper indium sulfide (CuInS 2 , CIS) has demonstrated fruitful results in solar cell technology and reported to be a shallow absorber in the visible region.…”

Improving the Photocatalytic Activity of Mesoporous Titania Films through the Formation of WS2/TiO2 Nano-Heterostructures

“…Some recent works about the photodegradation properties of TiO 2 composites are summarized for comparison in Supplementary Table S1 . Most of these publications focus on the photodegradation of dyes in aqueous solutions, such as methylene blue and RhB, by recording UV-Vis changes [ 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. Actually, the full degradation of organic pollutants cannot be truly detected from the UV-Vis changes, but instead from the infrared vibrations [ 18 , 19 ].…”

Optimization of Tungsten Disulfide/Polypyrrole Composite as Photocatalyst in Sunlight-Asissted Photodegradation of Methylene Blue in Aqueous Solution

“…This can be proven that the binary composites able to enhance photodegradation percentage of MB due to its excellent in optical absorption in the visible regions [28][29]. Furthermore, incorporation of PPy with WS 2 results in photogenerated electrons to be transferred from excited state to the conduction band of WS 2 particles e ciently [30]. Therefore, WS 2 /PPy was selected for the optimization analysis.…”