Heterogeneous catalysis of alkenes to alkanes is of great importance in chemical industry, but more efficient and reusable heterogeneous catalysts are still demanded. Here, we report a metallically gradated composite of a silicon nanowire array and palladium nanoparticles which are reused for the hydrogenation of an alkene. The catalyst promotes the hydrogenation of stilbene with atmospheric hydrogen (0.1 MPa) to give diphenylethane quantitatively. The recovered catalyst can be reused, and mediates the reaction without loss of yield more than one hundred times, whereas the stability of Pd/C degrades rapidly over 10 cycles of reuse. The catalyst allows the hydrogenation of a variety of alkenes, including tetra-substituted olefins. Structural investigation reveals that palladium nanoparticles are metallically gradated onto the silicon nanowire array under mild conditions by agglomeration of palladium silicide, as confirmed by XAFS and XPS together with argon-ion sputtering. This means of metal agglomeration immobilization may be applicable to the preparation of a variety of metal nanoparticle catalysts.

烯烃多相催化生成烷烃在化学工业中具有重要意义，但仍需要更高效、可重复使用的多相催化剂。在这里，我们报告了一种由硅纳米线阵列和钯纳米颗粒组成的金属渐变复合材料，可重复用于烯烃的氢化。该催化剂促进茋与常压氢气（0.1 MPa）加氢定量生成二苯乙烷。回收的催化剂可以重复使用，并且在不损失产率的情况下介导反应超过 100 次，而 Pd/C 的稳定性在重复使用 10 次后迅速下降。该催化剂允许各种烯烃加氢，包括四取代烯烃。结构研究表明，钯纳米粒子在温和条件下通过钯硅化物的团聚以金属方式渐变到硅纳米线阵列上，正如 XAFS 和 XPS 以及氩离子溅射所证实的那样。这种金属团聚固定化的方式可能适用于多种金属纳米粒子催化剂的制备。