Waste Biomass-Derived Activated Carbon-Supported 0D, 1D, 2D, and 3D Nanostructures of Copper Oxide for Hydrogenation Reaction: A Study on the Role of Structural Properties

Intensive attention is given to the morphology-controlled synthesis of inorganic nanomaterials because of their intrinsic shape-dependent properties. In this article, different dimensions (D) of copper oxide (CuO) nanoparticles (such as 0D-sphere, 1D-rod, 1D-belt, 2D-rolling pin sheets, 3D-octahedron, and 3D-throne) are prepared. The catalytic efficacy of these differently shaped CuO catalysts is compared for hydrogenation reactions under reducing agent-free conditions. The order of catalytic activity of the CuO catalyst is found to be belt > octahedron > rolling pin > rod > sphere > throne. The best catalyst among the different shaped CuO catalysts, namely belt shape, is supported on the functionalized groundnut shells activated carbon sheets (FGNC). Interestingly, 25 wt % CuO/FGNC catalysts exhibit the highest catalytic activity for the reduction of nitro compounds. Importantly, the highly active FGNC-supported catalyst is reused for up to 10 cycles without any noticeable loss in the catalytic activity.

Photocatalytic activity of the biogenic mediated green synthesized CuO nanoparticles confined into MgAl LDH matrix

The global concern over water pollution caused by organic pollutants such as methylene blue (MB) and other dyes has reached a critical level. Herein, the Allium cepa L. peel extract was utilized to fabricate copper oxide (CuO) nanoparticles. The CuO was combined with MgAl-layered double hydroxides (MgAl-LDHs) via a co-precipitation method with varying weight ratios of the CuO/LDHs. The composite catalysts were characterized and tested for the degradation of MB dye. The CuO/MgAl-LDH (1:2) showed the highest photocatalytic performance and achieved 99.20% MB degradation. However, only 90.03, 85.30, 71.87, and 35.53% MB dye was degraded with CuO/MgAl-LDHs (1:1), CuO/MgAl-LDHs (2:1), CuO, and MgAl-LDHs catalysts, respectively. Furthermore, a pseudo-first-order rate constant of the CuO/MgAl-LDHs (1:2) was 0.03141 min-1 while the rate constants for CuO and MgAl-LDHs were 0.0156 and 0.0052 min-1, respectively. The results demonstrated that the composite catalysts exhibited an improved catalytic performance than the pristine CuO and MgAl-LDHs. The higher photocatalytic performances of composite catalysts may be due to the uniform distribution of CuO nanoparticles into the LDH matrix, the higher surface area, and the lower electron and hole recombination rates. Therefore, the CuO/MgAl-LDHs composite catalyst can be one of the candidates used in environmental remediation.

Synthesis, biomedical applications, and toxicity of CuO nanoparticles

Versatile nature of copper oxide nanoparticles (CuO NPs) has made them an imperative nanomaterial being employed in nanomedicine. Various physical, chemical, and biological methodologies are in use for the preparation of CuO NPs. The physicochemical and biological properties of CuO NPs are primarily affected by their method of fabrication; therefore, selectivity of a synthetic technique is immensely important that makes these NPs appropriate for a specific biomedical application. The deliberate use of CuO NPs in biomedicine questions their biocompatible nature. For this reason, the present review has been designed to focus on the approaches employed for the synthesis of CuO NPs; their biomedical applications highlighting antimicrobial, anticancer, and antioxidant studies; and most importantly, the in vitro and in vivo toxicity associated with these NPs. This comprehensive overview of CuO NPs is unique and novel as it emphasizes on biomedical applications of CuO NPs along with its toxicological assessments which would be useful in providing core knowledge to researchers working in these domains for planning and conducting futuristic studies. KEY POINTS: • The recent methods for fabrication of CuO nanoparticles have been discussed with emphasis on green synthesis methods for different biomedical approaches. • Antibacterial, antioxidant, anticancer, antiparasitic, antidiabetic, and antiviral properties of CuO nanoparticles have been explained. • In vitro and in vivo toxicological studies of CuO nanoparticles exploited along with their respective mechanisms.

Dipotassium 1,3,4-thiadiazole-2,5-bis(thiolate) as a new S-donor for direct synthesis of symmetrical disulfides

In this research, a simple, efficient and novel protocol is eveloped for the direct synthesis of symmetrical disulfides using dipotassium 1,3,4-thiadiazole-2,5-bis(thiolate) as a new, low toxicity, inexpensive, stable solid and free of foul-smelling thiols for synthesize symmetric diaryl/dialkyl disulfides from aryl and alkyl halides in presence of MOF-199 and CuO nanoparticles. Significantly, using this method results in obtaining a variety of symmetrical disulfides in moderate to excellent yields (up to 98%).

Applications of metallic nanomaterials for the treatment of water

Water scarcity is not a novel issue. It has already affected almost every continent in this blue planet. It is driven by two primary sources: increasing demand for fresh water due to the increase in population and overexhaustion of the available freshwater resources. During the past decade, stress has been given to extract fresh, clean and safe potable elixir of life from the bountiful stores of sea water by exploiting various technologies. As nanomaterials are providing promising solutions to almost all our problems, they are again being accessed in order to combat the problem of global freshwater scarcity. Desalination methods have marvellously improved under the impact of nanomaterials. Different metallic nanomaterials are being used to serve this purpose; for example, silver, iron, zinc, titanium dioxide in addition to natural and synthetically derived polymeric bionanomaterials. In the present paper, a brief account of all the metallic nanomaterials which are being used for treatment of water has been provided by thorough investigation on the research done till now. It strives to throw light on various materials and methods which are based on the exploitation of nanotechnology for the treatment of water.