Interface enriched highly interlaced layered MoS2/NiS2 nanocomposites for the photocatalytic degradation of rhodamine B dye

Unraveling the effect of Cu doping on the structural and morphological properties and photocatalytic activity of ZrO2

Pristine ZrO2 and doped with different concentrations of Copper (0-7 %) were synthesized using a sol-gel combustion route. Several advanced techniques like XRD, EDX, TEM, XPS, P.L., and UV-vis spectrophotometer have characterized the compositions. The XRD proved that all peaks matched with a tetragonal phase of ZrO2 without any impurities of other phases. An average crystallite size rises from 20 to 55 nm by increasing the concentrations of Copper. The elemental analysis was examined by EDX and confirmed the presence of Cooper, Zirconium, and Oxygen. The red shift was observed due to a decrease in the bandgap (5.5-4.01 eV) with increasing the Cu concentrations. From the analysis of photocatalysis of pure ZrO2 and different concentrations of Cu-doped ZrO2 for M.B., RHB, and mix of them. The increase in doping of Cu led to enhancing the performance of the removing MB from 35 to 80 %, however, the RHB degradation was from 42 to 81 % while the mix of M.B. and RHB reached 85 % with 7 % Cu-doping ZrO2.

Effect of Sulfide and Chloride Ions on Pitting Corrosion of Type 316 Austenitic Stainless Steel in Groundwater Conditions Using Response Surface Methodology

This study investigates the corrosion resistance of Type 316 stainless steel as a candidate material for radioactive waste disposal canisters. The viability of stainless steel is examined under groundwater conditions with variations in pH, bisulfide ions (HS-), and chloride ions (Cl-) concentrations. Utilizing response surface methodology, correlations between corrosion factors and two crucial response variables, passive film breakdown potential and protection potential, are established. Cyclic potentiodynamic polarization tests and advanced analytical techniques provide detailed insights into the material's behavior. This research goes beyond, deriving an equation through response surface methodology that elucidates the relationship between the factors and breakdown potential. HS- weakens the passive film and reduces the pitting corrosion resistance of the stainless steel. However, this study highlights the inhibitory effect of HS- on pitting corrosion when Cl- concentrations are below 0.001 M and at equivalent concentrations of HS-. Under these conditions, immediate re-passivation occurs from the destroyed passive film to metal sulfides such as FeS2, MoS2, and MoS3. As a result, no hysteresis loop occurs in the cyclic polarization curve in these conditions. This research contributes to the understanding of Type 316 stainless-steel corrosion behavior, offering implications for the disposal of radioactive waste in geological repositories.

Photodegradation of rhodamine-B in aqueous environment using visible-active gC3N4@CS-MoS2 nanocomposite

Rapid industrial expansion leads to environmental pollution especially in an aqueous environment. Photocatalytic degradation is one of the most efficient and environmentally friendly techniques used to treat industrial pollution due to its complete degradation capability of a variety of water contaminants to their non-toxic state. Graphitic carbon nitride (gC3N4) and molybdenum disulfide (MoS2) provide efficient dye degradation, but MoS2 has few disadvantages. Hence, chitosan (CS) supported gC3N4-MoS2 hybrid nanocomposite was developed in this study to reduce these issues by accelerating the degradation of dye molecules such as rhodamine-B under visible light. The prepared gC3N4@CS-MoS2 hybrid nanocomposite was thoroughly characterized using various analytical tools including FTIR, XRD, SEM, EDX, XPS, UV-Visible, and PL spectra. Several influencing parameters such as irradiation time, initial pH, dosage, and initial dye concentration were optimized by batch mode. The photodegradation of rhodamine-B could be induced by the heterogeneous gC3N4@CS-MoS2-water hybrid nanocomposite. The narrow band gap of gC3N4@CS-MoS2 (1.80 eV) makes it suitable for effective degradation of rhodamine-B due to more active in the visible region and attained its highest degradation efficiency of 99% after 40 min at pH 8 with minimum dosage of 60 mg. The possible degradation mechanism was tentatively proposed for rhodamine-B dye molecules from aqueous environment. The present work shows a novel photocatalyst for the purification and detoxification of dye molecules as well as other water contaminants found in polluted wastewater.

Recent advances in synthesis, structural properties, and regulation of nickel sulfide-based heterostructures for environmental water remediation: an insight review

Heterostructured nanomaterials exhibit pronounced potential in environmental science, including the water purification, pollutant monitoring, and environmental remediation. Especially, their application through advanced oxidation processes has been found capable and adaptable in waste water treatment. In semiconductor photocatalysts, metal sulfides are the leading materials. However, for further modifications, the progresses on specific materials need to be overviewed. Among metal sulfides, nickel sulfides are the emerging semiconductors due to relatively narrow band gaps, high thermal and chemical stability, and cost effectiveness. The aim of the present review is to conduct a thorough analysis and summary of recent progress in the application of nickel sulfide-based heterostructures in water decontamination. Initially, the review introduces the emerging needs of the materials for environment following the characteristics features of metal sulfides with emphasis on nickel sulfides. Subsequently, synthesis strategies and structural properties of nickel sulfide (NiS and NiS₂)-based photocatalysts are discussed. Herein, controlled synthesis procedures to influence their active structure, compositions, shape, and size for the enhanced photocatalytic performances are also considered. Furthermore, there is discussion on heterostructures formed by metal modification, metal oxides, and carbon hybridized nanocomposites. In the continuation, the modified characteristics are investigated which favors the photocatalytic processes for degradation of organic contaminations in water. The overall study highlights significant improvements in degradation efficiency of hetero-interfaced NiS and NiS₂ photocatalysts towards organics that are comparable to expensive noble-metal photocatalysts. Finally, we also added a little on prospects for future advancement of nickel sulfide-based photocatalysts for applications in sustainable environmental remediation.

Z-scheme NiO/g-C3N4 nanocomposites prepared using phyto-mediated nickel nanoparticles for the efficient photocatalytic degradation

Highly-effective photocatalyst of NiO/g-C₃N₄ with was successfully synthesized by using phyto-mediated-synthesized nickel nanoparticles. The preparation was initiated by synthesizing nickel nanoparticles by using Tinosphora cordifolia stem extract under ultrasound-assisted method followed by the dispersing onto g-C₃N₄ structure. The study focused on physicochemical characterization and photocatalytic activity as function of the percentage of Ni in the nanocomposite. The photocatalytic activity examinations were carried out to rhodamine B and tetracycline photocatalytic oxidation. The results demonstrated that graphitic carbon nitride is effectively improved the photocatalytic activity of NiO for both photocatalytic oxidation reactions. From the varied Ni content of 5; 10; and 20 %wt., it was also found that the highest photoactivity was achieved by the composite having 10 %wt. of nickel content. The high effectivity was showed by degradation efficiency of 95% toward Rhodamine B and 98% toward tetracycline. The examination on effect of scavengers suggests that Z-scheme involved in the photocatalytic mechanism which facilitated the efficient separation of the photogenerated electron-hole pairs under visible light illumination. In summary, the present findings provide a green approach for fabricating the effective photocatalysts for organic contaminant degradation.

Defect mediated visible light induced photocatalytic activity of Co3O4 nanoparticle decorated MoS2 nanoflower: A combined experimental and theoretical study

In this work, Co₃O₄ nanoparticle-decorated MoS₂ (MoS₂@Co₃O₄) hetero-nanoflowers were synthesized by a facile hydrothermal method, and the effect of Co₃O₄ on the morphological, structural, optical, electronic, and photocatalytic properties of MoS₂ was analyzed. The surface morphology of MoS₂ and MoS₂@Co₃O₄ was studied via field emission electron microscopy (FE-SEM) and transmission electron microscopy (TEM), which revealed a strong interaction between the MoS₂ nanoflower and the nanoparticles. The X-ray diffraction pattern showed a decrease in the crystallite sizes from 7.35 nm to 6.26 nm due to the incorporation of Co₃O₄. The UV-Vis spectroscopy of the analysis revealed that the indirect band gap of MoS₂ was reduced from 1.89 eV to 1.65 eV with the incorporation of Co₃O₄ nanoparticles. Density functional theory (DFT) calculations were used to investigate the electronic properties of MoS₂ and MoS₂@Co₃O₄ hetero-nanoflowers, which also showed a reduction in the electronic band gap for the Co₃O₄ nanoparticles that were injected. The presence of defect states was also observed in the electronic property of MoS₂@Co₃O₄. The photocatalytic activity of the prepared composite and nanoflower is studied using an aqueous solution of methylene blue (MB), and the efficiencies are found to be 27.96% for MoS₂ and 78.89% for MoS₂@Co₃O₄. The improved photocatalytic efficiency of MoS₂@Co₃O₄ hetero-nanoflower can be attributed to narrowing the band gap together with the creation of defect states by the injection of nanoparticles that slows down electron-hole recombination rate by trapping charge carrier. The degradation analysis of the composite provides a new route for the purification of polluted water.

The application of photoelectrocatalysis in the degradation of rhodamine B in aqueous solutions: a review

The pollution of the water environment by industrial effluents is an ongoing challenge due to the rate of industrialisation and globalisation. Photoelectrocatalysis (PEC), an electrochemical advanced oxidation process, has proven to be an effective method for removing organics from wastewater. Photoelectrocatalysis is environmentally benign, cost-effective and easy to operate. In this present review, we examine the recent progress in the removal of rhodamine B dye, a common constituent of textile effluent released into the environment, through photoelectrocatalytic degradation. We present a detailed discussion on the use of different kinds of unmodified and modified photoanodes that have been explored for the photoelectrocatalytic removal of this dye. More importantly, discussions are presented on the mechanisms and kinetics of the degradation of rhodamine B dye using these photoanodes. Hence, this review will be beneficial for researchers in developing future projects in the area of wastewater treatments through photoelectrocatalysis.

The pollution of the water environment by industrial effluents is an ongoing challenge due to the rate of industrialisation and globalisation.