Abstract: In recent years, the electrochemical hydrogen evolution reaction (HER) has emerged as a promising approach for sustainable hydrogen production. Among various catalysts, Pd-based materials are regarded as the most promising alternatives to Pt-based counterparts. However, the excessively strong adsorption of hydrogen intermediates on Pd surfaces limits their HER efficiency. In this study, we report the synthesis of two-dimensional PdIr2 alloy nanosheets via an organic-precursor decomposition method. The formation of the alloy structure effectively modulates the electronic configuration of Pd, thereby enhancing its alkaline HER performance. Electrochemical measurements show that the PdIr2 alloy nanosheet catalyst achieves an overpotential of only 29 mV at a current density of 10 mA?cm-2 and a Tafel slope of 51.4 mV?dec-1, significantly outperforming commercial Pt/C and commercialc-Pd/C catalysts. In addition, the catalyst exhibits excellent long-term stability, with a voltage decay of only 63 mV over 136 h (average decay rate of 2.16 mV?h-1). Notably, the decay voltage remains within 10 mV over the final 116 h, demonstrating superior stability compared to the reference catalysts.

Key words: Pd-based catalysts, PdIr Alloy, Nanosheet, HER in Alkaline