Sodium Alginate–CuS Nanostructures Synthesized at the Gel–Liquid Interface: An Efficient Photocatalyst for Redox Reaction and Water Remediation

Abstract

The use of visible light to propel chemical reactions is an exciting area of study that is crucial in the current socioeconomic environment. However, various photocatalysts have been developed to harness visible light, which consume high energy during synthesis. Thus, synthesizing photocatalysts at gel–liquid interfaces in ambient conditions is of scientific importance. Herein, we report an environmentally benign sodium alginate gel being used as a biopolymer template to synthesize copper sulfide (CuS) nanostructures at the gel–liquid interface. The driving force for the synthesis of CuS nanostructures is varied by changing the pH of the reaction medium (i.e., pH 7.4, 10, and 13) to tailor the morphology of CuS nanostructures. The CuS nanoflakes obtained at pH 7.4 transform into nanocubes when the pH is raised to 10, and the nanostructures deform at the pH of 13. Fourier transform infrared spectroscopy (FTIR) confirms all the characteristic stretching of sodium alginate, whereas the CuS nanostructures are crystallized in a hexagonal crystal system, as revealed by the powder X-ray diffraction analysis. The high-resolution X-ray photoelectron spectroscopy (XPS) spectra show the +2 and −2 oxidation states of copper (Cu) and sulfur (S) ions, respectively. The CuS nanoflakes physisorbed a higher concentration of greenhouse CO2 gas. Owing to a lower band gap of CuS nanoflakes synthesized at a pH of 7.4, compared to other CuS nanostructures prepared at pH 10 and 13, CuS photocatalytically degrades 95% of crystal violet and 98% of methylene blue aqueous dye solutions in 60 and 90 min, respectively, under blue light illumination. Additionally, sodium alginate–copper sulfide (SA-CuS) nanostructures synthesized at a pH of 7.4 demonstrate excellent performance in photoredox reactions to convert ferricyanide to ferrocyanide. The current research opens the door to developing new photocatalytic pathways for a wide range of photochemical reactions involving nanoparticle-impregnated alginate composites prepared on gel interfaces.

Sodium alginate/carboxymethyl cellulose films embedded with liposomes encapsulated green tea extract: characterization, controlled release, application

“…[8][9][10] Among these alternatives, sodium alginate (SA) and carboxymethylcellulose (CMC) have gained signicant popularity. [11][12][13][14] SA, derived from brown algae, is a water-soluble and non-toxic natural polysaccharide. It contains a substantial amount of -COOgroups and exhibits polyatomic behavior in aqueous solutions, displaying a notable sensitivity to changes in pH.…”

Sodium Alginate–CdS Nanostructures: Reinforcing Chemoselectivity in Nitro-Organic Reduction and Dye Degradation through Photoinduced Electron Transfer

“…Further, the biobased polymers rendering various functional applications have acquired research momentum . Sodium alginate (SA), because of its ionic conductivity, biocompatibility, mechanical, electrical, and thermal stability, turns out to be a very effective biopolymer. , The ease of insertion of bivalent cations into SA solution can develop a stable physical hydrogel. The stability of SA is attributed to its composition, which consists of long sequences of M-blocks, G-blocks, and MG-blocks formed by joining polymer chains made of (1,4)-linked β- d -mannuronic acid (M), and its C-5 epimer α- l -guluronic acid (G) .…”

Selective dye adsorption by pH modulation on chemically modified nanopolyaniline by N-grafting of maleic acid

“…To date, photocatalytic degradation, 6–9 chemical oxidation, 10 biological decomposition, 11–13 electrochemical treatment 14 and adsorption 15–18 methods have been proposed to eliminate MB dyes from effluents before discharging them to the environment. Among the above techniques, adsorption technology has advantages, such as its ease, high efficacy, insensitivity to the contaminant substance, and flexibility.…”