Ruthenium nickel bimetallic nanoparticles embedded in nitrogen-doped carbon mesoporous spheres as a superior catalyst for the hydrogenation of toxic nitroarenes

In this work, the ruthenium nickel bimetallic nanoparticles embedded in nitrogen-doped carbon mesoporous spheres (RuNi@ N-CMS) as a novel catalyst were designed and prepared. Hydrogenation of toxic p-nitrophenol into p-aminophenol was carried out in an aqueous medium using the prepared nanostructure. The as-synthesized RuNi@ N-CMS nanostructure displayed a better catalytic activity in comparison to both Ni@ N-CMS and Ru@ NCMS nanostructures which can be ascribed to synergistic effects of ruthenium-nickel. In contrast to the nitrogendoped catalyst, RuNi@CMS showed less activity, possibly because nitrogen acts as a secondary active site. The rate constant and TOF values were found to be 6.77 x 10-3 and 0.825 s- 1 for hydrogenation of p-nitrophenol, respectively. Furthermore, RuNi@ N-CMS nanostructure was investigated in the reduction of nitroarene derivatives bearing electron-donating and electron-withdrawing groups. According to the kinetics study and Hammett plot of the reduction of nitroarenes, the cationic transition state is involved in the catalytic reaction. Most importantly, the catalyst could be recovered and reused after five consecutive runs without significantly deactivating.