Recyclable Ni3S4 Nanocatalyst for Hydrogenation of Nitroarenes

The synthesis of surface‐clean nanoparticles of Ni3S4, which is a rare phase of nickel sulphides, is described. Nanoparticles were synthesized in a single step via hexamethyldisilazane (HMDS) –assisted method using NiCl2 and thiourea as starting materials. This synthetic method yielded phase pure, spherical Ni3S4 nanoparticles of mean size 17 ± 4 nm having clean surfaces. The nanoparticles were characterized thoroughly by data obtained from Powder X‐ray diffraction (PXRD), Fourier‐transform infrared spectra (FT‐IR), Energy dispersive X‐ray analysis (EDAX) and Transmission electron microscopy (TEM) analyses. Since newly produced Ni3S4 nanoparticles in our reaction had exposed surfaces, the catalytic behaviour of these particles was assessed by using it as a catalyst in the reduction reaction of aromatic nitro groups. We have demonstrated Ni3S4 nanoparticle as a versatile catalyst for the nitro hydrogenation of both activated and deactivated nitrobenzenes using hydrazine as a hydrogen source to yield corresponding amines in high yield (∼90 %). The heterogeneous catalyst, Ni3S4 nanoparticles was recycled more than ten times without any change in its activity. We have ascribed the enhanced catalytic activity of these Ni3S4 nanoparticles to their clean surfaces without any surfactant molecules around them. The rare stoichiometric form of nickel sulphide (Ni3S4) nanoparticles with clean surfaces has been synthesized in a single step using the HMDS assisted method. Hitherto unexplored catalytic activity of Ni3S4 phase of nickel sulphide nanoparticles in the hydrogenation of nitroarenes is revealed. The excellent catalytic activity of Ni3S4 in spite of having less surface area is attributed to the clean, surfactant free surface of nanoparticles, which is an intrinsic advantage of HMDS‐assisted synthesis.