Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (1): 145-152.doi: 10.3866/PKU.WHXB201410241

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Preparation of Pd/Co Bimetallic Nanoparticles and Their Catalytic Activity for Hydrogen Generation

ZHAO Wan-Guo1,2, SU Li1,2, ZHOU Zhen-Ning1,2, ZHANG Hai-Jun1,2, LU Li-Lin3, ZHANG Shao-Wei1,2   

  1. 1. The State Key Laboratory of Refractory and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, P. R. China;
    2. College of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, P. R. China;
    3. College of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan 430081, P. R. China
  • Received:2014-07-09 Revised:2014-10-23 Published:2014-12-25
  • Contact: ZHANG Hai-Jun E-mail:zhanghaijun@wust.edu
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51272188, 51472184, 51472185), National Key Basic Research Programof China (973) (2014CB660802), Natural Science Foundation of Hubei Province, China (2013CFA086), and Foreign Cooperation Projects in Science and Technology of Hubei Province, China (2013BHE002).

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Abstract:

Reported here is a facile route for the synthesis of polyvinyl pyrrolidone (PVP)-stabilized Pd/Co bimetallic nanoparticles via a chemical co-reduction process. The effects of molar ratio of PVP and reducing reagent (NaBH4) to the total metal ions, and metal ion concentration and composition on the catalytic activity for hydrogen generation from NaBH4 over Pd/Co bimetallic nanoparticles (BNPs) were studied. The transmission electron microscopy (TEM) results indicated that the prepared Pd/Co bimetallic nanoparticles, which had an average size of 1.5-2.8 nm, showed much higher catalytic activity than Pd and Co monometallic nanoparticles (MNPs). The highest catalytic activity of all the prepared bimetallic nanoparticles was 15570 mol·mol-1·h-1 (the activity was normalized by the content of Pd in the BNPs), which was achieved with Pd/Co theoretical atomratio of 1/9. The higher catalytic activity of the Pd/Co BNPs compared with the corresponding MNPs was ascribed to electronic charge transfer effects; this hypothesis was validated using density functional theory (DFT) calculations, which showed that the Pd atoms were indeed negatively charged, while the Co atoms were positively charged because of electron donation fromthe Co atoms to the Pd atoms. The positively charged Co atoms and negatively charged Pd atoms acted as catalytic active sites for the hydrolysis reaction of the alkaline NaBH4 solution. Good catalytic stability was observed with the existing high catalytic activity, even after five runs of evaluating the catalytic activity. Moreover, no clear agglomeration was observed in the nanoparticle catalyst used. The corresponding apparent activation energy was determined as 54 kJ·mol-1, based on the kinetic study of the hydrogen generation achieved via the NaBH4 hydrolysis over the PVP-protected Pd10Co90 bimetallic nanoparticles.

Key words: Pd/Co, Bimetal nanoparticle, NaBH4, Catalytic hydrogen generation

MSC2000: 

  • O643.36