纳米Ni-Co-B非晶态合金抗氧化行为的原位XPS研究

采用原位XPS手段研究了纳米非晶态Ni-Co-B合金中B和Co的抗氧化行为、表面组成与氧化处理条件之间的关系以及各元素含量随深度的变化趋势.结果发现,氧优先氧化表面的元素B物种,在元素态B被完全耗尽后才开始氧化表面的元素态Co物种,在元素态B和Co均被完全氧化后,元素态Ni才开始被氧化.另外,研究还发现,在氧化过程中,B和Co的氧化物具有在表面富集的倾向.正是由于B和Co的优先被氧化才保护了催化加氢反应中的活性中心--元素态Ni.

In situ XPS Studies on the Anti-oxidation Effects of Nano-sized Ni-Co-B Amorphous Alloy

In situ XPS was used to study the anti-oxidation behavior of Co and B in nano-sized Ni-Co-B amorphous alloy and the relationship between the surface contents and the treating oxidation conditions by O_2 as well as the changes of the surface elemental contents with the depth of the sample. It was found that the elemental B was preferably oxidized, then the elemental Co could be oxidized. After all elemental B and Co were used up, the surface elemental Ni began to be oxidized by O_2. In addition, the oxides from B and Co were inclined to enrich on the surface after the oxidation. It was the preferential oxidation of B and Co that protected the Ni active centers from oxidation during the catalytic hydrogenation.