Copper nanowires (CuNWs) with a high aspect ratio of ~2600 have been successfully synthesized by using a facile hydrothermal method. The reductions of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and methylene blue (MB) to leucomethylene blue (LMB) by using sodium borohydride (NaBH₄) were used as models to test the catalytic activity of CuNWs. We showed that by increasing the CuNWs content, the rate of reduction increased as well. The CuNWs showed an excellent catalytic performance where 99% reduction of 4-NP to 4-AP occurred in just 60 s by using only 0.1 pg of CuNWs after treatment with glacial acetic acid (GAA). The rate constant (k_app) and activity factor (K) of this study is 18 and ~10¹⁰ fold in comparison to previous study done with no GAA treatment applied, respectively. The CuNWs showed an outstanding catalytic activity for at least ten consecutive reusability tests with a consistent result in 4-NP reduction. In clock reaction of MB, approximately 99% of reduction of MB into LMB was achieved in ~5 s by using 2 μg CuNWs. Moreover, the addition of NaOH can improve the rate and degree of recolorization of LMB to MB.

Plants have been used for multiple purposes over thousands of years in various applications such as traditional Chinese medicine and Ayurveda. More recently, the special properties of phytochemicals within plant extracts have spurred researchers to pursue interdisciplinary studies uniting nanotechnology and biotechnology. Plant-mediated green synthesis of nanomaterials utilises the phytochemicals in plant extracts to produce nanomaterials. Previous publications have demonstrated that diverse types of nanomaterials can be produced from extracts of numerous plant components. This review aims to cover in detail the use of plant extracts to produce copper (Cu)-based nanomaterials, along with their robust applications. The working principles of plant-mediated Cu-based nanomaterials in biomedical and environmental applications are also addressed. In addition, it discusses potential biotechnological solutions and new applications and research directions concerning plant-mediated Cu-based nanomaterials that are yet to be discovered so as to realise the full potential of the plant-mediated green synthesis of nanomaterials in industrial-scale production and wider applications. This review provides readers with comprehensive information, guidance, and future research directions concerning: (1) plant extraction, (2) plant-mediated synthesis of Cu-based nanomaterials, (3) the applications of plant-mediated Cu-based nanomaterials in biomedical and environmental remediation, and (4) future research directions in this area.

Hydrogen's potential as a clean energy carrier is increasingly recognized, but its storage remains a significant challenge. Sodium borohydride (NaBH4) stands out as an efficient hydrogen storage medium due to its high gravimetric capacity and safety profile. This review paper provides a comprehensive analysis of the research progress in NaBH4 hydrolysis for hydrogen production from 2004 to 2024. This paper discusses the advantages of NaBH4, including its high hydrogen yield, stability, controlled hydrogen release, and potential for regeneration into NaBH4 from the by-product sodium metaborate. This review surveys various catalysts used to enhance the hydrolysis reaction, such as cobalt, nickel, ruthenium, and noble metals, emphasizing their efficiency, recyclability, and economic viability. It also examines the influence of reaction conditions like temperature, pH, and NaBH4 concentration on the hydrolysis process. Additives and modifiers that improve reaction kinetics and hydrogen yield are also discussed. This paper further explores the regeneration and recycling of NaBH4, which is crucial for a sustainable hydrogen economy. It outlines three main approaches: thermochemical, mechanochemical, and electrochemical methods, each with its advantages and challenges. In conclusion, NaBH4 is a compelling hydrogen storage material with ongoing research aimed at overcoming the remaining challenges for its large-scale application. The development of more efficient and sustainable NaBH4 regeneration methods is essential for the future of clean energy.

Hydrogen (H₂) is a clean energy carrier which can help to solve environmental issues with the depletion of fossil fuels. Sodium borohydride (NaBH₄) is a promising candidate material for solid state hydrogen storage due to its huge hydrogen storage capacity and nontoxicity. However, the hydrolysis of NaBH₄ usually requires expensive noble metal catalysts for a high H₂ generation rate (HGR). Here, we synthesized high-aspect ratio copper nanowires (CuNWs) using a hydrothermal method and used them as the catalyst for the hydrolysis of NaBH₄ to produce H₂. The catalytic H₂ generation demonstrated that 0.1 ng of CuNWs could achieve the highest volume of H₂ gas in 240 min. The as-prepared CuNWs exhibited remarkable catalytic performance: the HGR of this study (2.7 × 10¹⁰ mL min⁻¹ g⁻¹) is ~3.27 × 10⁷ times higher than a previous study on a Cu-based catalyst. Furthermore, a low activation energy (E_a) of 42.48 kJ mol⁻¹ was calculated. Next, the retreated CuNWs showed an outstanding and stable performance for five consecutive cycles. Moreover, consistent catalytic activity was observed when the same CuNWs strip was used for four consecutive weeks. Based on the results obtained, we have shown that CuNWs can be a plausible candidate for the replacement of a costly catalyst for H₂ generation.

Textile industrialization causes water pollution due to the discharge of industrial effluents into the environment. To reduce the impact of industrial effluent, it must be treated in wastewater treatment plants before discharge into rivers. Among all wastewater treatment approaches, the adsorption process is one method to remove pollutants from wastewater, but it has some limitations in term of reusability and ionic selective adsorption properties. In this study, we prepared cationic poly (styrene sulfonate) (PSS)-incorporated anionic chitosan beads synthesized using the oil–water emulsion coagulation method. The produced beads were characterized using FESEM and FTIR analysis. In batch adsorption studies, the PSS-incorporated chitosan beads exhibited monolayer adsorption processes, that is, exothermic processes that occur spontaneously at low temperatures, which were analyzed based on the adsorption isotherms, adsorption kinetics, and thermodynamics model fittings. The presence of PSS enables cationic methylene blue dye to adsorb to the anionic chitosan structure via electrostatic interaction between the sulfonic group and the dye molecule. The maximum adsorption capacity of PSS-incorporated chitosan beads achieved 42.21 mg/g, as calculated from the Langmuir adsorption isotherm. Finally, the PSS-incorporated chitosan beads demonstrated good regeneration with different types of reagents, especially using sodium hydroxide as a regeneration reagent. With the use of sodium hydroxide regeneration of this adsorbent material, a continuous adsorption setup also demonstrated that PSS-incorporated chitosan beads can be reused for methylene blue adsorption for up to three cycle processes.