Impact of morphology and hierarchically porous properties of NiO-loaded chicken feather activated carbon composites on catalytic activity towards chromenes synthesis

Designing a wide range of nickel oxide (NiO) nanoparticle assorted morphologies, including fluffy sphere and hexagonal sheets, solid smooth sphere, and caterpillar-like nanoparticles, through precise engineering. The catalytic activity of tunned morphologies of NiO is compared for multicomponent condensation reactions of 4H-chromenes synthesis. The catalytic activity order is as follows: fluffy sphere > solid smooth sphere > hexagonal sheets > caterpillar shape of NiO. The results confirm that the catalytic activity is significantly influenced by the shape effect, which plays a predominant role. Besides, the biomass waste-activated carbon is used as a support and is produced from the Leghorn chicken feathers rachis. This biomass-waste chicken feather-activated carbon (CFAC) serves as a low-cost support material for the decoration of nickel oxide and reduces metal loading. The fluffy sphere NiO decorated on CFAC is prepared via the simple ultrasonic-assisted method. The catalytic performances are analyzed through the multicomponent reactions of different substituted aldehydes, 5,5-dimethylcyclohexanone, and malononitrile in a green solvent to form 4H-chromenes with the highest conversion of 90–99 % within 10–30 min. A meager amount (150 ppb) of Ni is found in the reaction mixture by ICP-OES analysis, which reveals the heterogeneous nature of the catalyst. Additionally, the nanocomposites are reused for up to 6 cycles without significant loss in activity. The 0.03 mmol of 15 wt% FS-NiO loaded CFAC catalyst is used effectively for the bulk-scale synthesis of chromene. This methodology offers several key benefits, including straightforward work-up, cost efficiency, non-toxicity, and environmentally friendly conditions.