The Role of Convex Edge Site in Fully-Exposed Pt Cluster Catalyst for Hydrogen Production

Abstract

Achieving a precise understanding of the active site structure has long been an ultimate goal in fundamental heterogeneous catalysis research, yet it remains exceptionally challenging in nanocluster catalysis. In Pt-catalyzed dehydrogenation reactions, such as cyclohexane dehydrogenation for liquid organic carriers (LOHC), previous efforts have provided valuable insights into the size effects of nanoclusters. However, the optimal geometry of the active sites has remained elusive and, at times, contradictory. In this study, we investigate the geometric effect and the active site structure in fully-exposed Pt clusters supported on ceria that exhibit superior activity in cyclohexane dehydrogenation (11.4 mol mol_Pt⁻¹ s⁻¹), characterized by small coordination numbers, high metal utilization efficiency, and abundant convex edge sites. Through a combination of experimental and theoretical approaches, we demonstrate that the convex edge sites predominant within the fully-exposed Pt clusters outperform other active structures (e.g., terrace sites, hollow sites, etc.) in dehydrogenation reactions. These convex edge sites are not only efficient in C─H activation but, more notably, are also resistant to detrimental carbonaceous intermediates, hence enabling high and long-lived H₂ production activity.