Compressed Intermetallic PdCu for Enhanced Electrocatalysis

Hydrogen evolution reaction (HER) is a key reaction in hydrogen production through water electrolysis. Platinum (Pt) is the best-known element for HER catalysis. Due to the scarcity of Pt, the development of non-Pt nanocatalysts is desired to achieve broad scale implementations. Here we demonstrate that the PdCu nanostructure containing an intermetallic B2 phase (PdCu-B2) shows a smaller Tafel slope, higher exchange current density, and lower overpotential for HER compared to commercial Pt/C in acidic conditions. Density functional theory (DFT) calculations demonstrate that the improved HER performance in acidic conditions can be attributed to the decrease in the hydrogen binding energy (HBE) on the compressed intermetallic PdCu-B2, shifting the HBE to a more optimal position even compared to Pt/C. In addition, PdCu-B2 exhibits the highest mass activity toward the formic acid oxidation reaction, making it a good anode catalyst candidate for formic-acid-based fuel cells.