Titanium (IV) oxide (TiO₂) having palladium (Pd) core-silver (Ag) shell nanoparticles (Pd@Ag/TiO₂) was prepared by using a two-step (Pd first and then Ag) photodeposition method. The core-shell structure of the nanoparticles having various Ag contents (shell thicknesses) and the electron states of Pd and Ag were investigated by transmission electron microscopy and X-ray photoelectron spectroscopy, respectively. The effect of the Pd core and the Ag shell was evaluated by hydrogenation of 4-octyne in alcohol suspensions of a photocatalyst under argon and light irradiation. 4-Octyne was fully hydrogenated to 4-octane over Pd/TiO₂, whereas 4-octyne was selectively hydrogenated to cis-4-octene over Pd(0.2)@Ag(0.5)/TiO₂. Further increase in the Ag content resulted in a decrease in the conversion of 4-octyne. Pd-free Ag/TiO₂ was inactive for hydrogenation of alkyne and induced coupling of active hydrogen species (H₂ production). Photocatalytic reactions at various temperatures revealed that the change in selectivity (semihydrogenation or H₂ production) can be explained by the difference in values of activation energy of the two reactions. An applicability test showed that the Pd@Ag/TiO₂ photocatalyst can be used for hydrogenation of various alkynes to alkenes.

具有钯（Pd）核-银（Ag）壳纳米粒子（Pd@Ag/TiO ₂）的钛（IV）氧化物（TiO ₂）是通过使用两步（先Pd，然后是Ag）光沉积方法制备的。分别通过透射电子显微镜和 X 射线光电子能谱研究了具有不同 Ag 含量（壳厚度）的纳米颗粒的核壳结构以及 Pd 和 Ag 的电子态。Pd 核和 Ag 壳的影响是通过 4-辛炔在光催化剂的醇悬浮液中在氩气和光照射下氢化来评估的。4-辛炔在Pd/TiO _{2 上}被完全氢化成4-辛烷，而4-辛炔在Pd(0.2)@Ag(0.5)/TiO _{2 上}被选择性氢化成顺式-4-辛烯. Ag含量的进一步增加导致4-辛炔转化率的降低。无 Pd 的 Ag/TiO ₂对炔烃的加氢和活性氢物质的诱导偶联（H ₂产生）是无活性的。不同温度下的光催化反应表明，选择性（半氢化或 H ₂生成）的变化可以用两个反应的活化能值的差异来解释。适用性试验表明，Pd@Ag/TiO ₂光催化剂可用于各种炔烃加氢制烯烃。