Abstract
Carbon spheres supporting nickel nanoparticles (NPs), generated by the integration of hydrothermal and microwave irradiation techniques, catalyzed the epoxidation of 1-octene, cyclooctene, styrene, allyl alcohol, and cyclohexene. The average particle sizes of the carbon spheres (CSs) and nickel oxide species immobilized on the CSs were 240 nm and 26 nm, respectively. The fabricated composites incorporating nickel NPs showed higher activity in the cyclohexene epoxidation process. The cyclohexene conversion was enhanced by raising the Ni loading to 10%. Within 14 h, the cyclohexene conversion had grown to 98%. This robust catalytic activity can be attributed to the efficient distribution of Ni species on the CSs, the facile lowering of the surface, and the development of uniformly nanosized species. The composite exhibited good recyclability across at least five cycles (which is not a simple task involving nickel-nanoparticle-based catalysts that are employed in water), and no nickel species leached into the solution, making the total system environmentally benign and cost-effective.