Bimetallic Sites for Catalysis: From Binuclear Metal Sites to Bimetallic Nanoclusters and Nanoparticles

Abstract

Heterogeneous bimetallic catalysts have broad applications in industrial processes, but achieving a fundamental understanding on the nature of the active sites in bimetallic catalysts at the atomic and molecular level is very challenging due to the structural complexity of the bimetallic catalysts. Comparing the structural features and the catalytic performances of different bimetallic entities will favor the formation of a unified understanding of the structure−reactivity relationships in heterogeneous bimetallic catalysts and thereby facilitate the upgrading of the current bimetallic catalysts. In this review, we will discuss the geometric and electronic structures of three representative types of bimetallic catalysts (bimetallic binuclear sites, bimetallic nanoclusters, and nanoparticles) and then summarize the synthesis methodologies and characterization techniques for different bimetallic entities, with emphasis on the recent progress made in the past decade. The catalytic applications of supported bimetallic binuclear sites, bimetallic nanoclusters, and nanoparticles for a series of important reactions are discussed. Finally, we will discuss the future research directions of catalysis based on supported bimetallic catalysts and, more generally, the prospective developments of heterogeneous catalysis in both fundamental research and practical applications.

Size-Dependent Structures and Catalytic Properties of Supported Bimetallic PtSn Catalysts for Propane Dehydrogenation Reaction

“…In most of the practical bimetallic catalysts, the active sites are based on bimetallic nanoparticles with particle sizes >1 nm. In recent years, bimetallic nanoclusters with particle sizes ≤1 nm have attracted increasing attention in the catalysis community because of their unique structural features and catalytic properties in various catalytic reactions in comparison to conventional bimetallic nanoparticles with sizes >1 nm …”

“…In recent years, bimetallic nanoclusters with particle sizes ≤1 nm have attracted increasing attention in the catalysis community because of their unique structural features and catalytic properties in various catalytic reactions in comparison to conventional bimetallic nanoparticles with sizes >1 nm. 2 From a fundamental point of view, the rational design of bimetallic catalysts relies on establishing reliable structure− reactivity relationships. 3 In principle, the knowledge accumulated with monometallic systems on the particle size effects can at least partly be translated into bimetallic systems.…”

Fluorination of Covalent Organic Framework Reinforcing the Confinement of Pd Nanoclusters Enhances Hydrogen Peroxide Photosynthesis

“…A key strategy for stabilizing the metal-isolated clusters is to physically confine them into porous supports, such as zeolites, , mesoporous silica, , hollow mesoporous carbon, , metal–organic frameworks (MOFs), , and covalent organic framework (COFs). − However, the simple physical confinements suffer from the stability decay of the catalyst during the catalytic process. Strong metal–support interaction (MSI) has been proved to stabilize metal-isolated clusters and promote electron transport simultaneously, which affects the catalytic durability and activity. , Rational design of support at the molecular level to increase the MSI is quite interesting in stabilizing metal-isolated clusters and tailoring its catalytic activity.…”

Heterobimetallic Trihydrido Complex of Ruthenium and Rhodium Supported by Cyclopentadienyl Groups with Different Steric Demands

“…Bimetallic catalysts have attracted extensive attention due to the synergistic effect arising from the presence of two different transition metals in close proximity, and it has been well-recognized that the bimetallic systems often yield dramatic improvements in catalytic activity and selectivity compared to the parent homometallic catalysts. − Mullins and co-workers elucidated that O adatoms at the Pd–Au interface sites are more reactive toward CO oxidation than those at the Pd surfaces by the investigation of Pd–Au model catalysts . However, the effect of an M–M’ interface in bimetallic nanoparticles is still unclear due to the complexity of the structures.…”