Photocatalytic activity of nanoparticles of metal sulfides in the degradation of organic dyes

Abstract

The photocatalytic degradation of dyes at the nanosized sulfides of transition metals in aqueous solutions was investigated. The rate of degradation increases with decrease in the synthesis temperature of the nanoparticles and with the addition of alcohol. The substitution of Cd 2+ cations by Ag + or Cu 2+ leads to a decrease in the photoactivity of the CdS, while substitution by In 3+ leads to an increase. The substitution of Ni 2+ and Co 2+ cations in the corresponding sulfides by Cd 2+ leads to an increase in the rate of degradation.Nanoparticles containing oxides, sulfides, and other inorganic compounds can exhibit high photocatalytic activity in synthesis, reforming, degradation, and other reactions of organic compounds [1][2][3][4]. Nanoparticles as photocatalysts have a substantial advantage over the microparticles formed by broadband semiconductors such as TiO 2 , ZrO 2 , ZnO, Fe 2 O 3 , etc. due to the fact that they do not scatter light, making it possible to utilize more fully the incident light.The initial process in photocatalysis at suspensions of broadband photocatalysts is the formation of hole (h + )/electron (e -) pairs, which can recombine or dissociate with the release of h + and e -to the surface of the catalyst particles [5]. The holes and electrons can interact with the substrates and also with molecular oxygen or surface hydroxyls, leading to the formation of highly reactive particles, the reaction of which with the substrates causes degradation of the latter.The present paper is devoted to an investigation into the photocatalytic characteristics of the nanoparticles formed by the sulfides of transition metals, including mixed sulfides, as illustrated by the degradation of dyes. A comparative study was made of the photocatalytic characteristics of cadmium, nickel, silver, manganese, copper, cobalt, and molybdenum sulfide nanoparticles. EXPERIMENTALThe nanoparticles were prepared in aqueous solutions of the salts (5×10 -3 M) (chlorides, sulfates, or nitrates) of the respective metals by the usual procedure [6]. Ammonium molybdate was used for the preparation of the MoS 3 nanoparticles. During the preparation of the nanoparticles a stabilizer in the form of sodium polyphosphate (sodium hexametaphosphate) or methylbenzethonium chloride (Aldrich) was added to the solution of the salt, and an equimolar amount of sodium sulfide was then added with vigorous stirring. In the photocatalytic experiments the concentration of the stabilizer was 2 g/L. 2820040-5760/06/4205-0282

Compound Copper Chalcogenide Nanocrystals

“…Table shows the results of the photodegradation tests found in the literature using Cu chalcogenides. The photodegradation of dyes and other organic molecules having an optical fingerprint was tested using a variety of Cu chalcogenide compositions and shapes, including CuS NCs, , CuS nanotubes, , CuS hierarchical nanostructures, ,, CuS, Cu 2 S, and Cu 1.8 S nanostructured flowers, ,, Cu 2 S microsponges, CuS nanostructures, ,− Cu 2 S NPs, − ZCIS NPs, ZCIS nanorods, CuSe nanoflakes, solid and hollow CISe NPs, Cu 2 Se nanowires, Cu 2 FeSnS 4 nanostructured spheres, CuSe 1− x S x nanoflakes, and Cu 2 ZnGeS 4 NCs . Interband materials, such as Sn-doped CGS and CIS NCs and Cr-doped CGS, have also been studied and are a particularly interesting class of materials, which have enhanced performances mediating dye photodegradation.…”

Smart Membrane Surfaces: Wettability Amplification and Self‐Healing

“…Metals oxides including TiO 2 or ZnO, Fe 2 O 3 , CdS and CuO are oft en used to promote the formation of super-oxide anions and hydroxyl radicals intermediates [70][71][72], which cause the chemical decomposition making oft en the surfaces photo-inductively hydrophilic and, then, easily washable. TiO 2 is one of the most used photocatalytic materials for its large availability, non-toxicity, chemical stability, biocompatibility and recyclability [73][74][75][76][77][78].…”

Cobalt-doped ZnS-reduced graphene oxide nanocomposite as an advanced photocatalytic material

“…It is therefore of great significance to adjust the band structure of photocatalysts to improve its photocatalytic efficiency towards the utilization of solar energy. Various attempts such as dye sensitization, coupling with different semiconductors, and doping with metals or nonmetals are performed to modify the bandgap of semiconducting photocatalysts [29][30][31][32].…”