Facet-Dependent Photoinduced Transformation of Cadmium Sulfide (CdS) Nanoparticles

Abstract

Microbial-mediated transformation of anthropogenic Cd 2+ controls its distribution, bioavailability, and potential risks. However, the processes readily form CdS nanoparticles (CdS-NPs), which exhibit dissolution behavior different from that of larger sized particles. Here, we investigated the effects of morphologies and facets of CdS-NPs on their photoinduced dissolution. Three CdS-NPs, CdS-sphere, CdS-rod, and CdS-sheet, and one nanosized biogenic CdS (Bio-CdS) were synthesized with different dominant facets of {101}, {100}, {001}, and {111} and thus distinct surface chemistry. As explored by HRTEM, EPR, and DFT calculations, photogenerated e − /h + pairs were more likely to generate on CdS-sheet surfaces due to higher surface energies and a narrower band gap, facilitating the formation of •OH and thereby faster dissolution (k obs = 6.126−6.261 × 10 −2 h −1 ). The wider band gaps of CdS-sphere and CdS-rod caused less formation of O 2•− and •OH, leading to slower oxidative dissolutions (k obs = 0.090−0.123 and 2.174−3.038 × 10 −2 h −1 , respectively). Given the similar surface energy as that of CdS-sheet, the dissolution rate of Bio-CdS was close to that of CdS-rod and CdS-sheet, which was 1.6−3.5 times faster than that of larger sized CdS, posing higher environmental risks than thought. Altogether, this work revealed the facet effects on the dissolution of CdS-NPs, manifesting a deeper understanding of metal sulfides' environmental behaviors.

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

“…In comparison, no XTT formazan formation or FFA degradation was observed upon irradiation of iron minerals, suggesting negligible O 2 •– and 1 O 2 production (Figure c,d). The absence of O 2 •– production is linked to the iron mineral band structure, where the CB positions of all iron minerals were more positive than the redox potentials of O 2 /O 2 •– , indicating that the photogenerated e – could not transfer to O 2 to form O 2 •– . Hence, • OH and H 2 O 2 were identified as the major ROS species from the photochemistry of iron minerals.…”

“…•− . 32 Hence, • OH and H 2 O 2 were identified as the major ROS species from the photochemistry of iron minerals.…”

Synergistic Effect of the Sulfur Vacancy and Schottky Heterojunction on Photocatalytic Uranium Immobilization: The Thermodynamics and Kinetics

“…The overall diameter of the CA was about 10 μm, and CdS-SV was evenly distributed on its surface [Figure b, and the scanning electron microscopy (SEM) image of CA@CdS is shown in Figure S1], which was also confirmed by SEM–energy-dispersive X-ray spectroscopy (EDX) elemental mapping (Figure c). The CdS-SV nanorods with a length of approximately 200 nm formed nanoflowers through self-assembly (Figure d), which could avoid photocorrosion to the greatest extent . In the region selected in Figure e, the lattice fringe spacing was 0.32 nm, corresponding to the (101) crystal plane of CdS .…”

“…The CdS-SV nanorods with a length of approximately 200 nm formed nanoflowers through self-assembly (Figure 1d), which could avoid photocorrosion to the greatest extent. 24 In the region selected in Figure 1e, the lattice fringe spacing was 0.32 nm, corresponding to the (101) crystal plane of CdS. 25 In addition, the transmission electron microscopy (TEM)−EDX elemental mapping of the corresponding selected region of CdS-SV nanorods indicated the high overlap of Cd and S elements (Figure 1f).…”

Hollow cubic CdS@CoS/WS2dual S-scheme heterojunction superstructure toward optimized photothermal–photocatalytic performance

“…14 To solve this problem, some reasonable strategies including combining metal sulfides with other layered oxides, combining them with microporous materials, coupling them with other catalysts, constructing heterojunctions, and changing the microstructure can be used to inhibit the photocorrosion of metal sulfides. 15,16 Rational design of the shape and structure of CdS is an effective strategy to suppress photocorrosion and improve the utilization of sunlight. The internal cavity of CdS is a hollow structure that can not only induce multiple reflection and refraction effects of light, but also effectively reduce the transmission distance of photogenerated carriers and lower the charge recombination rate.…”