Transformation of g-C₃N₄ into onion like carbon on nickel nanoparticles for ultrafast hydrogenation

It is known that increase in temperature of thermal oxidation exfoliation leads to increased nitrogen vacancies and in turn leads to high specific area of graphitic carbon nitride g-C₃N₄. In the present work we showed that thermal treatment of highly exfoliated (mono/few layers) g-C₃N₄ in the presence of nickel nanoparticles, which were pre-immobilized on to the surface of g-C₃N₄ layers, leads to formation of onion like carbon (OLCs) on surfaces of nickel nanoparticles. The immobilization of nickel nanoparticles was done by a simple NaBH₄ reduction-based grinding method. The formation of OLCs on Ni nanoparticles were confirmed using SEM and HR-TEM. The X-ray diffraction studies shows formation of diamond like OLCs phase on Ni nanoparticles. The surface area of Ni-OLCs was observed as 45.1 m²/g. XPS revealed the formation of sp²/sp³ hybrid diamond like OLCs. Also, thus formed materials acts as a very good magnetically separable catalyst for ultrafast hydrogenation of p-nitrophenol.