Recent Progress on Rational Design of Bimetallic Pd Based Catalysts and Their Advanced Catalysis

Bimetallic Pd based catalysts have received tremendous research interests for many important reactions in fields of important petrochemical industrial process, fine chemical synthesis, environment protection, renewable energy conversion, as their specific activity and selectivity are usually higher than that of pure Pd. With a well-defined composition, Pd–M bimetallic catalysts are also the ideal platform for the investigation of the reaction mechanism, which provides a bridge for the construction of high-performance catalyst. This Review intends to give an overview of the recent advances on the design principles of bimetallic Pd based catalyst in term of active sites' structure and number, and provide insights into the synergy effects between Pd and M as well as the supports to understand the elementary mechanisms of reactions. The Review starts with how the intrinsic activity and selectivity of different structures (alloy, core–shell, and Pd/metal compound interface) would be controlled by ligand effect, strain effect, ensemble effect, and support effect; followed by a discussion of the structure determined mechanism investigation in reactions of selective hydrogenation, CO oxidation, methane combustion, electrocatalytic energy conversion (HER, ORR, MOR), CO2 reduction, H2 production, biomass upgrading, and fine chemical synthesis; and then introduces the strategies for how to maximize the active sites' number in a finite metal load. Finally, the operando insight into the active sites' reconstruction under reaction condition will be discussed. On the basis of this Review, the experience and generic rules acquired from the design thoughts, synthetic disciplines, and the functionalities of bimetallic Pd based catalysts in a given reaction could have an important referential significance for revealing catalytic mechanisms at the molecular scales as well as building up other high-efficiency bimetallic catalysts.