Immobilizing Pd nanoclusters into electronically conductive metal-organic frameworks as bi-functional electrocatalysts for hydrogen evolution and oxygen reduction reactions

Abstract

Although noble metals, especially Pt and Pt-based materials, are the most efficient catalysts for electrocatalysis, their high cost, low abundance and the strong tendency to aggregate of nanoparticles hinder their further commercial applications. In recent years, metal-organic frameworks (MOFs) have been found to be promising templates for immobilizing nanoclusters (NCs) as advanced catalysts. However, their poor electrical conductivities largely limit their applications in the field of electrochemistry and electrocatalysis. In this study, electrically conductive MOF-74 is chose as template to immobilize tiny Pd NCs in the pores (Pd@MOF-74). Unlike the usually reported MOF-based electrocatalysts, without the post calcination process, the Pd@MOF-74 exhibited excellent electrocatalytic performances for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Moreover, due to the tiny size and the high dispersion of Pd clusters confined in the MOFs, the loading of noble Pd metal can be largely reduced for the catalysis. Meanwhile, the Pd clusters immobilized in the MOF-74 showed higher long-term durability in both acid and alkaline electrolytes than commercial Pt/C.