Optical properties and photocatalytic activity of CdS-TiO2/graphite composite

Abstract

TiO2 film was applied to graphite substrate through chemical bath deposition (CBD) method with TiCl4 as precursor. CdS was deposited on TiO2/graphite (TiO2/G) by CBD with precursors of CdSO4. A UV-Vis diffuse reflectance (UV-Vis DR) analysis was used to analyze the optical properties and band gap energy. Meanwhile, photocatalytic activity was determined from the quantum yield (QY) value of isopropanol degradation. The X-ray diffraction pattern shows that the TiO2 film contains rutile and anatase phases. UV-Vis DR spectrum shows the photoactivity in the visible light area and provides lower band gap value due to CdS deposition. TiO2/G provide energy gap at 3.0 eV, which indicates that rutile phase is dominant. Meanwhile, CdS-TiO2/G shows multiple energy gaps representing CdS at 2.4 eV, rutile at 3.0 eV, and anatase at 3.2 eV. The QY values of CdS-TiO2/G are 7.98×10-3 and 8.62×10-4 at 450 and 380 nm of radiation light, respectively. These values are higher than the QY of TiO2/G and TiO2-P25/graphite (TiO2-P25/G), which are 1.19×10-4 and 5.0×10-4, respectively. The photocatalytic reaction follows the first-order reaction. CdS deposition allows the rate constant to increase from 2×10-3 to 13×10-3 under UV radiation.

In situ fabrication of a direct Z-scheme photocatalyst by immobilizing CdS quantum dots in the channels of graphene-hybridized and supported mesoporous titanium nanocrystals for high photocatalytic performance under visible light

“…1a shows three diffraction peaks at 26.5, 44.0, and 52.1°, which are in good agreement with the main (111) reflection and two weaker (220) and (311) reflections of the standard cubic CdS (JCPDS: 80-0019), confirming the crystalline phase of the QDs in CdS/GR. 31 In addition, the XRD patterns also reveal that the principal peaks, consistent with the crystalline phases of (101), (004), (200), (105), and (211), were found for both the CdS@GMT/GR-2 and GMT/GR nanocomposites, indicating that the obtained samples primarily consisted of the anatase phase. Meanwhile, there are no the peaks corresponding to CdS for CdS@GMT/GR-2.…”

“…5b by the Kubelka–Munk function ( F ( R ∞ ) = (1 − R ) 2 /(2 R ), where R is the reflectance). 31 The bandgap energies (E g ) of CdS@MT, CdS/GR, and GMT/GR were determined as ca. 2.90, 2.60, and 2.95 eV, respectively, which suggests a light-responsive transition from the UV to the visible-light region.…”

The Photocatalytic Activity of Zns-TiO2 on a Carbon Fiber Prepared by Chemical Bath Deposition

“…Our previous research on a graphite substrate found that TiO 2 /G had a quantum yield of 1.96 x 10 -3 at 380 nm of a light source, and that the value increased to 6.0 x 10 -2 when the ZnS layer was coated on TiO 2 /G. the graphite substrate proved to contribute to the photocatalytic activity [14]. Low-density carbon material, which is known as exfoliated graphite, also showed a good performance on the electrochemical degradation of p-nitro phenol [15].…”

Photocatalytic and antibacterial activity of graphene oxide/cellulose-doped TiO2 quantum dots: in silico molecular docking studies

“…Moreover, the lone pairs of electrons enabling n → π* transitions resulted in a further redshift in the peaks (360–460 nm) in CNC:TiO 2 . 38 The absorption range increased in the visible range upon doping GO in CNC–TiO 2 , showing improved light-harvesting ability. This can be attributed to the relatively easy excitation of the lone electrons in contrast to the bonded electrons, resulting in more n → π* as compared to π → π* transitions.…”

“…Peaks between 360-420 nm in GO/CNC-doped TiO 2 were attributed to π→π* transition of atomic C-C ring and C-O bond. Moreover, lone pairs of electrons enabling n→π* transitions resulted in further redshift of peaks (360-460 nm) in CNC:TiO 2[38]. The absorption range increased in visible range upon GO doped in CNC-TiO 2, showing improved light harvesting ability.…”