Green synthesis of Size‐Controlled copper oxide nanoparticles as catalysts for H2 production from industrial waste aluminum

Summary Extensive research and development in the processes of production and generation of hydrogen are needed to make renewable hydrogen cost‐competitive with fossil hydrogen. As a result, developing hydrogen energy from low‐cost components and synthesizing it from renewable resources is an important issue that can be considered a global challenge. The current research provided a continuous H 2 energy production from waste aluminum in a water medium using copper oxide nanoparticles (CuO NPs) as catalysts in the reaction. CuO NPs have been prepared by a green, easy, inexpensive, and systematic method using Catha edulis L. (Khat) extract as reducing and capping agents. Separately, CuO NPs prepared in an alkaline media using the conventional hydrothermal process have been described and reported for comparison. Multidisciplinary tools were used to characterize the powders for structural, morphological, and surface aspects. CuO NPs were homogeneous, well‐dispersed, and have fine diameters with an average of 6 nm , owing to the abundant biomolecules in the plant extract. The synthesized samples were utilized as catalysts for H 2 production from industrial waste aluminum with a 1/0.02 ration of Al/CuO by weight. The primary results revealed a higher H 2 production yield and rapid rate in alkaline than acidic mediums. Under all conditions, the CuO NPs prepared from the extract had better catalytic activity than those prepared by a conventional method. The results proved that the reaction temperature prompts the reaction kinetics more than other parameters. The optimum H 2 yield could be optimized at a temperature of 70°C, 1/50 ratio of CuO/waste Al, and near‐neutral solutions. The above conditions are ideal for designing a continuous production reactor. The hydrogen generated using industrial waste aluminum in the present system is a cost‐effective and sustainable approach.