Enhanced photodegradation of methylene blue from aqueous solution using Al-doped ZnS nanoparticles

The post-transition semiconducting material of pure zinc sulfide (ZnS) and various concentrations of aluminum (Al) (2.5 wt%, 5.0% wt, 7.5 wt%, and 10% calcined at 200 °C) doped ZnS nanoparticles (NPs) were synthesized by sol-gel procedure. The crystal-like nature and phase structure of the product were examined by powder XRD analysis. This analysis shows that the pure ZnS nanoparticle does not form any secondary phase. The functional group of synthesized materials was analyzed by FTIR examination. The energy gap of the materials is calculated using electro-optic analysis and the Kubelka-Munk equation varies from 3.04 nm to 3.63 nm. The photoluminescence studies show the wide emissions (blue to green) for pure ZnS and Al-doped ZnS nanomaterials. The SEM images show the spherical structure and the agglomerated nanostructures. The presence of Zn, S, and Al are confirmed by EDAX spectra. From HR-TEM studies, pure ZnS and Al-doped ZnS nanoparticles exhibit uniform particle sizes. The rate of degradation was observed using MB dye. MB dye has maximum wavelength (λ_max) of 664 nm. The dye degradation efficiency was improved as the dye ratio increased. Photocatalytic activities studies show the intensity of photocatalytic activities decreased for the maximum time interval. Doping of Al in ZnS boosts the photocatalytic activity. Hence, Al-doped ZnS appears to be better decomposing MB dye when exposed to visible light.

Review elucidating graphene derivatives (GO/rGO) supported metal sulfides based hybrid nanocomposites for efficient photocatalytic dye degradation

Photocatalysis by utilizing semiconductors for the removal of toxic pollutants has gained tremendous interest for remediation purposes. The organic pollutants usually include; pesticides, dyes and other phenolic compounds. An imperative restraint associated with the photocatalytic effectiveness of the catalyst is the rapid recombination of the light generated electrons and holes. The particle agglomeration and electron-hole recombination hinders the rate of pollutant removal. For decades, researchers have used metal-sulfides efficiently for photocatalytic dye degradation. The recent use of hybrid nanomaterials with the combination of graphene derivatives such as graphene oxide and reduced graphene oxide (GO/rGO)-metal sulfide has gained interest. These composites have displayed an impressive upsurge in the photocatalytic activity of materials. The current review describes the various researches on dye photodegradation by employing (GO/rGO)-metal sulfide, exhibiting a boosted potential for photocatalytic dye degradation. A comprehensive study on (CuS, ZnS and CdS)–GO/rGO hybrid composites have been discussed in detail for effective photocatalytic dye degradation in this review. Astonishingly improved dye degradation rates were observed in all these studies employing such hybrid composites. The several studies described in the review highlighted the varying degradation rates based on diverse research parameters and efficacy of graphene derivatives for enhancement of photocatalytic activity.

Graphene-based composite membranes for isotope separation: challenges and opportunities

Graphene-based membranes have got significant attention in wastewater treatment, desalination, gas separation, pervaporation, fuel cell, energy storage applications due to their supreme properties. Recently, studies have confirmed that graphene based membranes can also use for separation of isotope due to their ideal thickness, large surface area, good affinity, 2D structure etc. Herein, we review the latest groundbreaking progresses in both theoretically and experimentally chemical science and engineering of both nanoporous and lamellar graphene-based membrane for separation of different isotopes. Especially focus will be given on the current issues, engineering hurdles, and limitations of membranes designed for isotope separation. Finally, we offer our experiences on how to overcome these issues, and present an ideas for future improvement and research directions. We hope, this article is provide a timely knowledge and information to scientific communities, and those who are already working in this direction.

Recent progress in decontamination system against chemical and biological materials: challenges and future perspectives

Environmental contamination is one of the key issues of developing countries in recent days, and several types of methods and technologies have been developed to overcome these issues. This paper highlights the importance of decontamination in a contaminated environment that normally precedes protection, detection and identification followed by medical support. Further, this paper especially focuses on individual and collective NBC decontamination required on navy ships and correspondingly presents solutions (viable and economical) through the use of indigenously developed decontamination equipment. The paper also highlights the integration of various decontamination technologies with pre-existing ship decontamination systems, indicating the need for various decontaminants. Finally, we will also focus on new decontamination systems based on nanomaterials and enzymes and their utilization.

Newfangled progressions in the charge transport layers impacting the stability and efficiency of perovskite solar cells

Organic-inorganic lead halide perovskite solar cells have rapidly emerged as a newfangled material for solar energy harnessing. Perovskite solar cells have succeeded in gaining a power conversion efficiency of 25% in the last year, further enhancement in the efficiency is anticipated due to advanced engineering of the different components making up the complete cell architecture with enhanced performance, stability and efficiency. Significant components of perovskite solar cell configurational architecture are the electron transport layer, active perovskite absorber layer, hole transport layer and counter electrode. Considering the profound role of transport layers in charge mobility, current review has particularly elucidated the advancements in the charge transport layers. The time duration of the review is from 2010 to 2021. However, the special focus has been laid on the recent articles. The influence of different organic and inorganic materials used for development of transport layers influencing the cell performance have been summarized. Materials used for transport layers have been modified by utilization of myriad of engineered substances through doping and surface functionalization strategies but every method have been marked by posing serious challenges towards the stability and efficiency of the cell and thus, hindering its commercialization. The review also provides an elucidation of the mechanical challenges and abatement strategies. These strategies are associated with the charge transport layers for enhancement of cell functionality.