Alkali elements have been applied as promoters of noble metals (e.g., Pd or Pt) to enhance their catalytic activities by changing the surface electronic states of the noble metals. In particular, the role of alkali elements is to improve the dispersion properties of the active metal. In this study, various amounts of the alkali element sodium (Na) were used as a promoter for a Pd/TiO₂ catalyst. Importantly, the catalysts were synthesized to improve the selectivity and production rate of the direct synthesis of hydrogen peroxide (DSHP) by increasing the Pd dispersion and surface area by changing the surface electronic properties. After the addition of Na onto Pd/TiO₂, the H₂O₂ production rates were generally higher than those for pure Pd/TiO₂ due to the synergistic effects between the Pd and Na on the TiO₂ support. Particularly, among the tested catalysts, the 0.5 wt.% Na-promoted Pd/TiO₂ (PdNa(0.6)/TiO₂) catalyst exhibited the highest H₂ conversion rate (22 %) in the iso-Pd weight and the highest H₂O₂ selectivity (95.4 %) and production rate (785.9 mmol/g_Pdh) for the iso-H₂ conversion test. Na provides electrons to the Pd species, leading to a change in the Pd dispersion. Furthermore, the surface electronic state of Pd changed with increasing amounts of Na, and thus, heavily influenced the H₂O₂ selectivity. Ultimately, PdNa(0.6)/TiO₂ achieved the best selectivity as a H₂O₂ producing catalyst in this study.

碱元素已被用作贵金属（例如Pd或Pt）的促进剂，以通过改变贵金属的表面电子态来增强其催化活性。特别地，碱金属元素的作用是改善活性金属的分散性能。在这项研究中，各种数量的碱金属元素钠（Na）被用作Pd / TiO ₂催化剂的促进剂。重要的是，通过改变表面电子性能，通过增加Pd的分散度和表面积来合成催化剂，以提高直接合成过氧化氢（DSHP）的选择性和生产率。在Pd / TiO ₂上添加Na之后，H ₂ O ₂由于Pd和Na对TiO ₂载体的协同作用，生产速率通常高于纯Pd / TiO _2的生产率。特别地，在测试的催化剂中，0.5wt。％的Na-促进的Pd / TiO ₂（PdNa（0.6）/ TiO ₂）催化剂在iso-Pd重量中表现出最高的H ₂转化率（22％）和最高的H iso-H _2的2 O ₂选择性（95.4％）和产率（785.9 mmol / g _Pd h）转换测试。Na向Pd物质提供电子，导致Pd分散度发生变化。此外，Pd的表面电子状态随着Na的含量的增加而变化，因此严重影响了H ₂ O _2的选择性。最终，在本研究中，PdNa（0.6）/ TiO ₂作为产生H ₂ O _2的催化剂获得了最佳的选择性。