Sustainable solid-state synthesis of uniformly distributed PdAg alloy nanoparticles for electrocatalytic hydrogen oxidation and evolution

New sustainable syntheses based on solid-state strategies have sparked enormous attention and provided novel routes for the synthesis of supported metallic alloy nanocatalysts (SMACs). Despite considerable recent progress in this field, most of the developed methods suffer from either complex operations or poorly controlled morphology, which seriously limits their practical applications. Here, we have developed a sustainable strategy for the synthesis of PdAg alloy nanoparticles (NPs) with an ultrafine size and good dispersion on various carbon matrices by directly grinding the precursors in an agate mortar at room temperature. Interestingly, no solvents or organic reagents are used in the synthesis procedure. This simple and green synthesis procedure provides alloy NPs with clean surfaces and thus an abundance of accessible active sites. Based on the combination of this property and the synergistic and alloy effects between Pd and Ag atoms, which endow the NPs with high intrinsic activity, the PdAg/C samples exhibit excellent activities as electrocatalysts for both the hydrogen oxidation and evolution reactions (HOR and HER) in a basic medium. Pd9Ag1/C showed the highest activity in the HOR with the largest j0,m value of 26.5 A g Pd−1 and j0,s value of 0.033 mA cmPd−2, as well as in the HER, with the lowest overpotential of 68 mV at 10 mA cm−2. As this synthetic method can be easily adapted to other systems, the present scalable solid-state strategy may open opportunity for the general synthesis of a wide range of well-defined SMACs for diverse applications.