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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。
Polyvinylpyrrolidone (PVP) -based Pd / Ni bimetallic nano-sols were prepared by chemical reduction method. The synthesized Pd / Ni bimetallic nano-sols were characterized by TEM, HR-TEM and so on. The amount of reductant, the concentration of metal salt and the proportion of metal on the sol-type bimetallic nano-catalyst. The results show that the average particle size of the prepared Pd / Ni bimetallic nano-sol is about 2 nm, and the activity of the NaBH 4 hydrogenation catalyzed by the bimetallic nano-sol catalyst is superior to that of the single metal Pd and Ni nano-sols. Among them, the catalytic activity of Pd 10 Ni 90 bimetallic nano sol was the highest, and the catalytic activity of NaBH 4 to produce hydrogen could reach 8250 mol H 2 mol -1 Pd -1 · h -1. The activation energy of NaBH 4 hydrolysis catalyzed by Pd_ (20) Ni_ (80) bimetallic nanosized sol was 35.7 kJ / mol, the enthalpy of reaction was 33.3 kJ / mol and the entropy of reaction was -150 J / mol. The results also show that the prepared Pd / Ni bimetallic nanosized catalyst has good catalytic stability, and the catalyst still retains high catalytic activity even after four catalytic tests. Density functional theory calculations show that the electron transfer between the Ni atom and the Pd atom causes the Pd atom to be negatively charged and the Ni atom to be positively charged. The charged Pd and Ni atoms become active centers for the catalytic reaction.