Lately, palladium (Pd) nanoparticles (NPs) have gathered significant attention in various fields due to their unique properties and diverse applications in catalysis. Particularly noteworthy their role in the hydrogen evolution reaction (HER), owing a high catalytic activity, synergistic effects in alloy catalysts, wide operating pH range, and compatibility with renewable energy technologies, making Pd a crucial catalyst for sustainable energy conversion and storage applications. [1] In this study, we synthesized Pd-based NPs immobilized on Vulcan-carbon support with approximately 20% wt. using a surfactant-free top-down approach known as an electrochemical erosion. [2] This method relies on the erosion of metal substrates immersed in an electrolyte, such as a wire, while applying an alternating sinusoidal voltage to these substrates, resulting in NPs production. [2], [3] An essential step in the synthesis process involves the pretreatment of the Pd bulk substrate, leading to material embrittlement and facilitating the homogeneous distribution of NPs with a size below 10 nm on the support during electrochemical erosion. The produced Pd NPs exhibited a polyhedral shape and surpassed the commercial catalyst from Fuel Cell Store in performances, including specific surface area, geometric activity, mass activity, specific activity, and durability. [2] Furthermore, we optimized the catalyst by including copper (Cu) into the composition. To synthesize PdCu/C via electrochemical erosion, a precursor salt of Cu was added to the electrolyte. The optimized PdCu/C catalyst demonstrated improved electrochemical activity towards HER compared to both the previously synthesized Pd/C catalyst and the commercial Pd/C catalyst.