CdS QDs-Decorated Self-Doped γ-Bi₂MoO₆: A Sustainable and Versatile Photocatalyst toward Photoreduction of Cr(VI) and Degradation of Phenol

Abstract

In this work, CdS quantum dots (QDs)-sensitized self-doped Bi 2 MoO 6 has been synthesized using glucose as reducing agent by hydrothermal method, followed by in situ deposition of the QDs. The synthesized catalyst has been employed to reduce toxic Cr(VI) and degrade phenol from the aqueous solution. The structural, optical, and electrochemical characterizations are performed using X-ray diffraction, UV–vis diffuse reflection, photoluminescence (PL), scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. The optical properties were precisely investigated by calculating the Urbach energy, PL, and photoluminescence excitation spectra. The orderly distribution of QDs is confirmed from the correlation between full width at half-maximum of PL spectra, Urbach energy, and TEM analysis. The versatile photocatalytic activity has been tested toward Cr(VI) reduction and degradation of phenol. 3% CdS QDs-sensitized self-doped Bi 2 MoO 6 showed highest activity, i.e., 97 and 47.5% toward reduction of Cr(VI) and degradation of phenol under solar light. The reduction of Cr(VI) by the catalyst is supported by the kinetics and determination of the pH PZC value. In addition to this, the photostability and reusability test showed that the catalyst can be reused up to five cycles without diminishing its activity.

Strongly Coupled g‐C3N4 Nanosheets‐Co3O4 Quantum Dots as 2D/0D Heterostructure Composite for Peroxymonosulfate Activation

“…The HRTEM images further confirmed the anchoring of Co 3 O 4 QDs on CNNS nanosheets and demonstrated the formation of Co 3 O 4 /CNNS heterojunction, in which the particle size of Co 3 O 4 QDs was centered at ≈2.2–3.2 nm, matching well with the statistical particle size distribution diagram (Figure F–H). That is, the particle size of Co 3 O 4 QDs is small enough to exhibit the quantum confinement effect . Moreover, the distances of ≈0.200 and ≈0.243 nm correspond to the (400) and (311) planes in the spinel Co 3 O 4 lattice, respectively (Figure H) .…”

“…Moreover, the distances of ≈0.200 and ≈0.243 nm correspond to the (400) and (311) planes in the spinel Co 3 O 4 lattice, respectively (Figure H) . Obviously, high crystallinity and ultrasmall particle size will accelerate photogenerated carrier to diffuse toward the surface, thus enhances its photocatalytic activity . Furthermore, both Co 3 O 4 QDs and CNNS are in tight contact with each other to form heterojunction in the interfacial area, which can efficiently retard the photogenerated electron/hole recombination and enhance the possibility of photogenerated charge participating in AOPs.…”

“…That is, the particle size of Co 3 O 4 QDs is small enough to exhibit the quantum confinement effect. [55,62] Moreover, the distances of ≈0.200 and ≈0.243 nm correspond to the (400) and (311) planes in the spinel Co 3 O 4 lattice, respectively ( Figure 5H). [54] Obviously, high crystallinity and ultrasmall particle size will accelerate photogenerated carrier to diffuse toward the surface, thus enhances its photocatalytic activity.…”

Magnetically Separable Fe3O4@CdS Type‐II Nanohybrids with Excellent Photocatalytic Activity and Antibacterial Properties

“…[15] They demonstrated that incorporation of CdS QDs into BiOI microplates (up to 4wt%)c ould improve the photocatalytic efficiencies to al arge extent. The enhanced performance was attributed to increased visible absorption and the significant separation of electron-hole pairs over CdS/BiOI type-II heterostructures.P arida and co-workers [16] designed CdS QD decorated self-doped Bi 2 MoO 6 nanocomposites and demonstrated their superior photocatalytic performance toward the degradation of phenol and fast reduction of toxic Cr VI .T he 3% CdS QD sensitized self-doped Bi 2 MoO 6 sample displayed Am agnetically separable Fe 3 O 4 @CdS type-II core-shell nanohybrid (NH) photocatalyst, with excellent antibacterial properties and photocatalytic activity,w as synthesized and characterized by means of structural, elemental, and morphological analyses. Steady-state and time-resolved emission and absorption spectroscopyw ere also exploited to realize the location of chargecarrier wave functions in the NHs.…”

“…The enhanced performance was attributed to increased visible absorption and the significant separation of electron–hole pairs over CdS/BiOI type‐II heterostructures. Parida and co‐workers designed CdS QD decorated self‐doped Bi 2 MoO 6 nanocomposites and demonstrated their superior photocatalytic performance toward the degradation of phenol and fast reduction of toxic Cr VI . The 3 % CdS QD sensitized self‐doped Bi 2 MoO 6 sample displayed the highest efficiency, namely, 47.5 and 97 %, toward the degradation of phenol and reduction of Cr VI , respectively, under solar light.…”