Arnosti Nina A, Wyss Vanessa, Delley Murielle F
Department of Chemistry, University of Basel, 4058 Basel, Switzerland.
J Am Chem Soc. 2023 Nov 1;145(43):23556-23567. doi: 10.1021/jacs.3c07312. Epub 2023 Oct 24.
Transition metal phosphides have shown promise as catalysts for water splitting and hydrotreating, especially when a small amount of sulfur is incorporated into the phosphides. However, the effect of sulfur on catalysis is not well understood. In part, this is because conventional preparation methods of sulfur-doped transition metal phosphides lead to sulfur both inside and at the surface of the material. Here, we present an alternative method of modifying cobalt phosphide () with sulfur using molecular S-transfer reagents, namely, phosphine sulfides (SPR). SPR added sulfur to the surface of and using a series of SPR reagents having different P═S bond strengths enabled control over the amount and type of sulfur transferred. Our results show that there is a distribution of different sulfur sites possible on the surface with S-binding strengths in the range of 69 to 84 kcal/mol. This provides fundamental information on how sulfur binds to an amorphous surface and provides a basis to assess how number and type of sulfur on influences catalysis. For the catalytic hydrogenation of cinnamaldehyde, intermediate amounts of sulfur with intermediate binding strengths at the surface of were optimal. With some but not too much sulfur, exhibited a higher hydrogenation productivity and a decreased formation of secondary reaction products. Our work provides important insight into the S-effect on the catalysis by transition metal phosphides and opens new avenues for catalyst design.
过渡金属磷化物已显示出有望成为水分解和加氢处理的催化剂，特别是当少量硫掺入磷化物中时。然而，硫对催化作用的影响尚未得到很好的理解。部分原因在于，传统的硫掺杂过渡金属磷化物制备方法会导致硫既存在于材料内部也存在于材料表面。在此，我们提出一种使用分子硫转移试剂，即硫化膦（SPR），用硫修饰磷化钴（）的替代方法。SPR将硫添加到的表面，并且使用一系列具有不同P═S键强度的SPR试剂能够控制硫转移的量和类型。我们的结果表明，在表面上可能存在不同硫位点的分布，其S结合强度在69至84千卡/摩尔范围内。这提供了关于硫如何与无定形表面结合的基本信息，并为评估上硫的数量和类型如何影响催化作用提供了基础。对于肉桂醛的催化加氢，在表面具有中等结合强度的中等量硫是最佳的。有一些但不是太多的硫时，表现出更高的加氢生产率和减少的副反应产物形成。我们的工作为硫对过渡金属磷化物催化作用的影响提供了重要见解，并为催化剂设计开辟了新途径。
