Flower-like copper sulfide nanocrystals are highly effective against chloroquine-resistant plasmodium falciparum and the malaria vector Anopheles stephensi

Anopheles stephensi is a mosquito of outstanding public health relevance, acting as a major vector of malaria in a number of tropical and subtropical areas worldwide. In recent years, important efforts have been conducted to propose nano-formulated larvicides as valuable alternatives to synthetic insecticides currently marketed. In the present study, the toxicity of flower-like copper sulfide (CuS) nanocrystals has been investigated on the malaria vector A. stephensi and Plasmodium parasites. Characterization of synthesized CuS nanocrystals was carried out using FTIR spectroscopy, XRD analysis, FESEM, HR-TEM and EDS. In mosquitocidal assays, LC50 values ranged from 23.347 ppm (first-instar larvae) to 48.789 ppm (pupae). In vitro anti-plasmodial activity of CuS nanoflowers was evaluated against chloroquine-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. IC50were 83.44 μg/mL (CQ-s) and 87.15 μg/mL (CQ-r). However, in vivo antiplasmodial experiments conducted on Plasmodium berghei infecting albino mice showed limited activity of CuS nanocrystals, if compared to CQ. Overall, our findings showed that chemically synthesized flower-like CuS nanocrystals are promising to improve the effectiveness of mosquito control programs, as well as to develop novel antiplasmodial drugs

Integrated Remediation Processes Toward Heavy Metal Removal/Recovery From Various Environments-A Review

Addressing heavy metal pollution is one of the hot areas of environmental research. Despite natural existence, various anthropomorphic sources have contributed to an unusually high concentration of heavy metals in the environment. They are characterized by their long persistence in natural environment leading to serious health consequences in humans, animals, and plants even at very low concentrations (1 or 2 μg in some cases). Failure of strict regulations by government authorities is also to be blamed for heavy metal pollution. Several individual treatments, namely, physical, chemical, and biological are being implied to remove heavy metals from the environment. But, they all face challenges in terms of expensiveness and in-situ treatment failure. Hence, integrated processes are gaining popularity as it is reported to achieve the goal effectively in various environmental matrices and will overcome a major drawback of large scale implementation. Integrated processes are the combination of two different methods to achieve a synergistic and an effective effort to remove heavy metals. Most of the review articles published so far mainly focus on individual methods on specific heavy metal removal, that too from a particular environmental matrix only. To the best of our knowledge, this is the first review of this kind that summarizes on various integrated processes for heavy metal removal from all environmental matrices. In addition, we too have discussed on the advantages and disadvantages of each integrated process, with a special mention of the few methods that needs more research attention. To conclude, integrated processes are proved as a right remedial option which has been detaily discussed in the present review. However, more research focus on the process is needed to challenge the in situ operative conditions. We believe, this review on integrated processes will surely evoke a research thrust that could give rise to novel remediation projects for research community in the future

Recent Advances in Metal Chalcogenides (MX; X = S, Se) Nanostructures for Electrochemical Supercapacitor Applications: A Brief Review

Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because of their superior performance characteristics, including short charging time, high power density, safety, easy fabrication procedures, and long operational life. An SC consists of two foremost components, namely electrode materials, and electrolyte. The selection of appropriate electrode materials with rational nanostructured designs has resulted in improved electrochemical properties for high performance and has reduced the cost of SCs. In this review, we mainly spotlight the non-metallic oxide, especially metal chalcogenides (MX; X = S, Se) based nanostructured electrode materials for electrochemical SCs. Different non-metallic oxide materials are highlighted in various categories, such as transition metal sulfides and selenides materials. Finally, the designing strategy and future improvements on metal chalcogenide materials for the application of electrochemical SCs are also discussed

Highly Water Dispersible Polymer Acid-Doped Polyanilines as Low-Cost, Nafion-Free Ionomers for Hydrogen Evolution Reaction

While research efforts are devoted toward exploring low-cost electrocatalysts for hydrogen evolution reaction (HER), little attention is paid to another expensive component of the catalyst layerionomers. Both the electrocatalyst and a proportionately large amount of ionomer are required for a large-scale production of hydrogen. Presently, commercially available expensive Nafion is the state-of-the-art ionomer for proton conduction in the electrocatalyst layer. Interpolymer composites such as polymer acid-doped polyanilines (PANI) could be low-cost alternatives to Nafion. Highly water-dispersible PANI polymers doped with poly­(2-acryl-amido-2-methyl-1-propanesulfonic acid) (PAAMPSA)the polymer backbone of which is similar to that of Nafionhave been explored as cheaper alternatives to Nafion in acid medium. PANI-PAAMPSA, poly­(<i>ortho</i>-toluidine)-PAAMPSA, and poly­(<i>meta</i>-toluidine)-PAAMPSA have been used as ionomers in MoS₂ and CoSe₂ electrocatalysts. Electrocatalysts with PANI-PAAMPSA ionomers have achieved the highest HER activities and the lowest Tafel slopes in comparison to that with Nafion. Specifically, poly­(<i>meta</i>-toluidine)-PAAMPSA has been found as a promising alternative to Nafion ionomer. Replacing expensive Nafion in the electrocatalyst layer with PANI-PAAMPSA-based ionomers would further reduce the cost of hydrogen in a large-scale production

Fabrication of Cost-Effective Dye-Sensitized Solar Cells Using Sheet-Like CoS2 Films and Phthaloylchitosan-Based Gel-Polymer Electrolyte

Platinum-free counter electrodes (CE) were developed for use in efficient and cost-effective energy conversion devices, such as dye-sensitized solar cells (DSSCs). Electrochemical deposition of CoS2 on fluorine-doped tin oxide (FTO) formed a hierarchical sheet-like structured CoS2 thin film. This film was engaged as a cost-effective platinum-free and high-efficiency CE for DSSCs. High stability was achieved using a phthaloychitosan-based gel-polymer electrolyte as the redox electrolyte. The electrocatalytic performance of the sheet-like CoS2 film was analyzed by electrochemical impedance spectroscopy and cyclic voltammetry. The film displayed improved electrocatalytic behavior that can be credited to a low charge-transfer resistance at the CE/electrolyte boundary and improved exchange between triiodide and iodide ions. The fabricated DSSCs with a phthaloychitosan-based gel-polymer electrolyte and sheet-like CoS2 CE had a power conversion efficiency (PCE, η) of 7.29% with a fill factor (FF) of 0.64, Jsc of 17.51 mA/cm2, and a Voc of 0.65 V, which was analogous to that of Pt CE (η = 7.82%). The high PCE of the sheet-like CoS2 CE arises from the enhanced FF and Jsc, which can be attributed to the abundant active electrocatalytic sites and enhanced interfacial charge-transfer by the well-organized surface structure

MXene based emerging materials for supercapacitor applications: Recent advances, challenges, and future perspectives

In the past few decades, with the advancement of technology, there has been an increasing demand for high-capacity energy storage devices having durability, low production cost, and flexibility. MXene, a layered 2D transition metal carbide, nitride or carbonitride, exfoliated from its parent MAX phase by selective chemical etching of covalently bonded A layer has become the most emerging material today for energy storage applications. The 2D layered structure, atomic layer thickness, high conductivity, tunable surface functional groups, superior hydrophilicity, good mechanical properties, excellent electrochemical nature, flexibility, and the ease of preparation of MXene has made it the most demanding material today among 2D families. Starting from gas and biosensors, water purification, water splitting, photo and electrocatalysis, transparent conductors in electronics, antibacterial film, electromagnetic interference shielding, and in batteries and supercapacitors, MXene have a wide range of applications. The special properties of MXene have made scientists work on its further theoretical and experimental developments. This article mainly reviews the recent advances of MXene for fabricating durable, pliable, and highly efficient electrochemical energy storage devices using supercapacitors as its power source. The structure of MXene, different synthesis methods, and their unique properties have been deeply studied, as well as the effect of various factors like size and shape of MXene sheets, design of electrode architecture, nature of electrolyte, etc. on the electrochemical performance and charge storage mechanism of MXene based supercapacitors have been emphasized. This article also throws light on state-of-the-art recent progress in MXene composite-based supercapacitors. Finally, its challenges and future advances have been discusse