Pd/Ni双金属纳米溶胶的制备及催化制氢性能的研究  

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

作　　者：赵万国 李文[1] 鲁礼林[1] 李发亮[1] 张海军[1] 张少伟[1] 

机构地区：[1]武汉科技大学省部共建耐火材料与冶金国家重点实验室,湖北武汉430081

出　　处：《稀有金属材料与工程》2016年第12期3160-3166,共7页Rare Metal Materials and Engineering

基　　金：国家自然科学基金面上项目(51272188;51472184;51472185);"973"计划前期研究专项(2014CB660802);湖北省自然科学基金重点项目(2013CFA086);湖北省科技支撑计划对外科技合作项目(2013BHE002)

摘　　要：采用化学共还原法制备了聚乙烯吡咯烷酮(PVP)稳定的Pd/Ni双金属纳米溶胶,采用TEM、HR-TEM等对所合成的Pd/Ni双金属纳米溶胶进行了表征,并系统研究了PVP用量、还原剂用量、金属盐离子浓度及金属比例等对该溶胶型双金属纳米催化剂的影响。结果表明:所制备的Pd/Ni双金属纳米溶胶的平均粒径在2 nm左右,双金属纳米溶胶催化剂催化NaBH_4制氢活性优于单金属Pd和Ni纳米溶胶的活性。其中Pd_(10)Ni_(90)双金属纳米溶胶的催化活性最高,其催化NaBH_4制取氢气的活性可以达到8250 mol_(H2)·mol_(Pd)^(-1)·h^(-1),Pd_(20)Ni_(80)双金属纳米溶胶催化剂催化NaBH_4水解反应的活化能为35.7 kJ/mol,反应焓为33.3 kJ/mol,反应熵为-150 J/mol。研究结果还表明,所制备的Pd/Ni双金属纳米溶胶催化剂具有很好的催化稳定性,即使4次催化试验后该催化剂仍然保持着较高的催化活性。密度泛函理论计算结果表明,Ni原子与Pd原子之间发生的电子转移使得Pd原子带负电而Ni原子带正电,荷电的Pd和Ni原子成为催化反应的活性中心。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 nanocatalysts with an average size of 2 nm are superior to those of monometallic Pd nanocatalyst with the same size. The Pd（10）Ni（90） 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 Pd（20）Ni（80） bimetallic nanoparticles are 35.7 k J/mol, 33.3 k J/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.

关 键 词：Pd/Ni双金属 催化活性 纳米溶胶 硼氢化钠 制氢 

分 类 号：O643.36[理学—物理化学]