Preparation of Colloidal Pd/Ni Bimetallic Nanoparticle Catalysts and Their Catalytic Activity for Hydrogen Generation from Hydrolysis Reaction of Sodium Borohydride

This paper reported a facile route for synthesizing PVP stabilized Pd/Ni bimetallic nanosol by a chemical co-reduction process. The morphology, size, structure and composition of the resultant Pd/Ni bimetallic nanosol were characterized by transmission electron microscopy (TEM). The effects of PVP amount, reducing agent amount and metal composition on the hydrolysis of NaBH4 were studied. The results indicate that the catalytic activities of the prepared Pd/Ni bimetallic nano catalysts with an average size of 2 nm are superior to those of monometallic Pd nanocatalyst with the same size. The Pd10Ni90 bimetallic nanosol shows the highest catalytic activity with hydrogen generation rates of 8250 mol(H2).mol(Pd)(-1).h(-1) at 303 K, and the activation energy, enthalpy and entropy of Pd20Ni80 bimetallic nanoparticles are 35.7 kJ/mol, 33.3 kJ/mol and -150 J/mol, respectively. In addition, the prepared Pd/Ni bimetallic nanosol has a good catalytic activity even after the fourth cycle. The high catalytic activity of the Pd/Ni BNPs can be ascribed to electronic charge transfer effects. And DFT calculations reveal that Pd atoms are indeed negatively charged with the positively charged Ni atoms. The positively charged Ni atoms and negatively charged Pd atoms act as catalytic active sites for the hydrolysis of the alkaline NaBH4 solution.