Synthesis of Palladium-Tungsten Metallene-Constructed Sandwich-Like Nanosheets as Bifunctional Catalysts for Direct Formic Acid Fuel Cells

Although great efforts have been made over past decades, it is very challenging to develop advanced bifunctional electrocatalysts for direct formic acid fuel cells. Herein, we report the preparation of PdW metallene-constructed sandwich-like nanosheets (S-PdW NSs) via a facile wet-chemical method. This nanostructure shows excellent electrocatalytic activity and durability in both formic acid oxidation and oxygen reduction reactions. The remarkable enhancement of catalytic activity could be mainly attributed to its unique metallene-constructed sandwich-like nanosheets, whose layered structure could provide appropriate distances at the atomic scale close to the diameter of oxygen and formic acid molecules to realize bridge adsorption. The significantly improved durability could be due to the modification of the electronic structure of Pd via the introduction of W into the Pd lattice to generate strong bonding interactions. This work offers a low-Pd-loading, highly active, and stable bifunctional catalyst for direct formic acid fuel cells.