Conflicting Roles of Coordination Number on Catalytic Performance of Single-Atom Pt Catalysts
Conflicting Roles of Coordination Number on Catalytic Performance of Single-Atom Pt Catalysts
复制标题
DOI：
10.1021/acscatal.1c00627
复制
发表时间：
2021-04-22
期刊：
影响因子：
12.9
通讯作者：
Kim, Jae-Hong
中科院分区：
文献类型：
--
作者：
Huang, Dahong;He, Ning;Kim, Jae-Hong
调整金属原子的配位数是提高单原子催化剂催化性能的方法之一。我们在此展示了将单原子Pt加载到半导体SiC衬底（Pt-1/SiC）上，其高负载高达9.6% wt %，并精确控制其CN从3到5。通过光还原和80 ~ 160℃的温和热处理，将有机连接剂结合在衬底表面并保留金属连接剂键，实现了CN调谐。在更高的温度下，Pt与来自表面Si-OH基团和有机连接剂的额外氧原子配合。这导致Pt-1在80℃处理时CN由3增加到160℃处理时的5。具有不同CN的Pt-1/ sic通过H-2热催化和H*作为强还原原子氢（H原子）源的光催化有效地破坏了模型溴化化合物中的C- br键。热催化脱溴动力学随CN的减小而增大。然而，光催化脱溴动力学与CN无关，与文献中普遍的理解相矛盾。我们将这两种催化方案的不同CN效应归因于h原子形成途径的不同以及整个反应途径的限速步骤的不同。我们的研究提供了一个独特而重要的例子，说明SACs的性能和CN的作用如何根据催化方案而显着变化。
Tailoring the coordination number (CN) of metal atoms has been increasingly recognized as one of the strategies to enhance the catalytic performance of single-atom catalysts (SACs). We here present the single-atom Pt loaded onto a semiconductor SiC substrate (Pt-1/SiC) with a high loading of up to 9.6 wt % and a precise control of its CN from 3 to 5. The CN tuning was enabled by binding organic linkers on the substrate surface and retaining the metal-linker bonds after photoreduction and mild thermal treatment from 80 to 160 degrees C. At a higher temperature, Pt became coordinated with additional oxygen atoms from the surface Si-OH groups and organic linkers. This resulted in the increase of the CN from 3 for Pt-1 treated at 80 degrees C to 5 at 160 degrees C. The Pt-1/SiCs with varying CNs effectively broke C-Br bonds in the model brominated compounds through both thermocatalysis using H-2 and photocatalysis using H* as the source for strongly reducing atomic hydrogen (H-atom). The thermocatalytic debromination kinetics increased with the decreasing CN. However, photocatalytic debromination kinetics were independent of the CN, contradictory to the prevalent understanding in literature. We attribute the differential CN effects on these two catalytic schemes to the differences in the pathways for the formation of H-atom as well as the rate-limiting step of the overall reaction pathways. Our study presents a unique and important example as to how the performance of SACs and the role of CN can significantly vary depending on the catalytic schemes.