Green synthesis of 3D hierarchical nanostructured Co3O4/carbon catalysts for the application in sodium borohydride hydrolysis

Nowadays, the green synthesis of bare nano-crystalline metal oxides as well as the hetero-structured nanomaterials, utilizing various biological substrates, attracted the interest of many research groups. Various biological materials have been utilized as templates as well as carbon sources. This synthesis route is characterized by being low-cost, high-efficiency and eliminates the use of hazardous costly chemicals. The presented research paper focuses on the development of a novel green synthetic strategy for preparing three-dimensional (3D) hierarchical Co₃O₄/carbon nanoparticles. In this strategy, basil leaves extract (BLE) has been employed as a green-inexpensive template and carbon source. Calcination was performed at the 300–700 °C range. The prepared nanoparticles have been characterized using a series of integrated tools (XRD, FT-IR, FE-SEM, TEM, N₂ adsorption EDX and XPS). During calcination, the BLE provided the sufficient carbon to maintain the ordered structure of Co₃O₄/C nanoparticles. The development of the 3D porous hierarchical was obtained when the calcination is affected at 500 °C. The various Co₃O₄/carbon nanoparticles have been tested for their catalytic application towards hydrogen generation via the sodium borohydride hydrolysis. Our results demonstrated that activity is controlled by the presence of the 3D porous hierarchical nanoparticles as well as the calcination temperature.