Co 3 O 4 nanoparticles embedded in triple-shelled graphitic carbon nitride (Co 3 O 4 /TSCN): a new sustainable and high-performance hierarchical catalyst for the Pd/Cu-free Sonogashira–Hagihara cross-coupling reaction in solvent-free conditions

Inspired by the synthesis of triple-shelled periodic mesoporous organosilica hollow spheres, a straightforward and controllable approach for the preparation of Co 3 O 4 NPs embedded in triple-shelled graphitic carbon nitride has been established through a combinatorial route comprising the hard-templating technique and impregnation method. A series of various techniques such as FT-IR, XRD, BET, TEM, FE-SEM, EDX, EDX mapping, TGA, and ICP-OES have been used for the full characterization of the catalyst. It was found that the Co 3 O 4 /TSCN has a high performance to promote Sonogashira–Hagihara cross-coupling reaction in solvent-free conditions. Interestingly, the architecture of the catalyst provides not only the high dispersion loading of the Co 3 O 4 NPs on the support, but also facilitates the favorable mass transfer through the catalyst structure. The catalyst could be readily separated from the reaction mixture by filtration method and used again up to five times without any evident decrease in catalytic activity. Graphical abstract The superior catalytic performance of the Co 3 O 4 /TSCN as a new sustainable hierarchical catalyst has been presented for Pd/Cu-free Sonogashira–Hagihara cross-coupling reaction under solvent-free conditions