Shape-Controlled Synthesis of Gallium-Palladium (GaPd2) Nanomaterials as High-Performance Electrocatalysts for Hydrogen Evolution Reaction

Shape-controlled synthesis of GaPd2 nanomaterials including polyhedrons, nanoparticles and nanowires was achieved by a facile hot injection method. All the as-synthesized catalysts exhibit superior HER activity than the commercial pure Pd catalyst and stable in the acidic medium. Among them, the GaPd2 nanoparticles required only 24.3 mV overpotential to achieve the 10 mA/cm2 current density, which is superior to most of the Pt based nanomaterials. Also, cycling tests for 10000-cycle CV sweep (−0.3 to 0.2 vs. RHE) and durability test for 24 hours were applied, the GaPd2 catalysts exhibit similar i-V curves and stable current densities to those obtained in the initial tests. We further evaluate the mass activities of the GaPd2 catalysts, and it is fascinating that the GaPd2 polyhedrons, nanoparticles and nanowires achieved factors of 3.7, 5 and 2.3 enhancement in mass activity at -0.1 V vs. RHE compared with the commercial Pd black catalyst. Meanwhile, with the assistance of a reduced graphene oxide (rGO) support, the GaPd2 nanoparticles/rGO (20 wt%) electrocatalyst presents outstanding HER activity comparable with that of carbon supported platinum (Pt) catalyst (20% Pt/C). This work provides an avenue to develop effective and stable Pd–based catalysts with reducing Pd usage and high HER performance.