Water-Soluble Ag–Sn–S Nanocrystals Partially Coated with ZnS Shells for Photocatalytic Degradation of Organic Dyes

Abstract

Water-soluble nonrare metal Ag–Sn–S nanocrystals (ATS NCs) were green synthesized at room temperature using the interfacial nucleation mechanism. Interfacial acids regulate the concentration of hydroxide ions outside the complex, the sulfur sources attack the cations at the complex interface, and the sulfur sources form covalent bonds to complete crystal nucleation and growth at room temperature. The band gap of ATS NCs synthesized by the interface nucleation mechanism is 2.32∼2.59 eV, which gives it a higher redox ability and very high photocatalytic degradation rate. A total of 0.8 mg of Ag2SnS3 NCs can achieve photocatalytic degradation of more than 99% of MO (1 mg) under visible light (λ > 420 nm) in 2 min with a photocatalytic rate constant of 2.1247 min–1. Interfacial regulation of acid protonation on the surface of ATS NCs produced more defect states, which was conducive to trapping holes (h+), promoting their transfer to organic pollutants, and improving the photocatalytic oxidation degradation efficiency. Active species of trapping experiments showing photocatalytic degradation of active species as h+, ·O2–, and ·OH do not act as active species for MO degradation in this system. ATS NCs have ultra-high photocatalytic activity and further improve their photocatalytic efficiency by partially coated ZnS shells. Finally, we present the mechanism of photocatalytic degradation of ATS NCs and analyze the possible applications of ATS NCs. Due to its unique advantages of direct synthesis in organic pollutants at room temperature, it is expected to achieve a breakthrough in the practical treatment of large-scale industrial wastewater.

Visible-Light-Responsive Photoreversible Color Switching of Oxygen-Deficient WO3–x Hierarchical Nanostructures for Long-Legible Rewritable Paper

“…48,52 The normal hydrogen electrode (NHE) potential values of WO 3−x hierarchical nanostructures and WO 3 nanorods (pH = 6.5) can be calculated to −0.18 and −0.09 V, according to the following equation: E (NHE) = E (Ag/AgCl) + 0.197. 53,54 As a result, the band alignments of WO 3 nanorods and WO 3−x hierarchical nanostructures are obtained based on the bandgap value and Mott−Schottky curves (Figure 4d). Then, the E (NHE) values of WO 3−x hierarchical nanostructures and WO 3 nanorods are calculated to be 0.20 and 0.29 V (vs NHE, pH 0) according to the Nernst equation.…”

Application of 3D printing technology for green synthesis of Fe2O3using ABS/TPU/chlorella skeletons for methyl orange removal

“…9. Specically, isopropanol (IPA) was employed to capture hydroxyl radicals (OHc), ammonium oxalate (AO) served as a scavenger for photogenerated holes (h + ), 1-4 benzoquinone (BQ) was utilized to trap superoxide radicals (O 2 − ), and potassium dichromate (K 2 Cr 2 O 7 ) was chosen to capture photogenerated electrons (e − ), 30 as a control group, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was also used to inhibit free radicals. The representative reaction equations for the degradation of MO were as follows:…”

Hollow TiO2–SiO2 Nanospheres for Photocatalytic Degradation of Organic Dyes

“…The surface elements and valence states of h-TiO 2 /SiO 2 were analyzed by X-ray photoelectron spectroscopy (XPS, Thermo Scientific K-Alpha). 38 The morphology of the composite h-TiO 2 /SiO 2 was captured by field-emission scanning electron microscopy 39 (SEM, Zeiss Sigma 300) at an accelerating voltage of 10 kV, and the samples were sputter-coated with a gold film before observation. The surface morphology of the photocatalysts during synthesis, including the carbon sphere templates and h-TiO 2 , was observed by transmission electron microscopy (TEM, FEI Talos F200X G2).…”