Stable Pd–Cu Hydride Catalyst for Efficient Hydrogen Evolution

Pd has been regarded as one of the alternatives to Pt as a promising hydrogen evolution reaction (HER) catalyst. Strategies including Pd–metal alloys (Pd–M) and Pd hydrides (PdH x ) have been proposed to boost HER performances. However, the stability issues, e.g., the dissolution in Pd–M and the hydrogen releasing in PdH x, restrict the industrial application of Pd-based HER catalysts. We here design and synthesize a stable Pd–Cu hydride (PdCu 0.2 H 0.43 ) catalyst, combining the advantages of both Pd–M and PdH x structures and improving the HER durability simultaneously. The hydrogen intercalation is realized under atmospheric pressure (1.0 atm) following our synthetic approach that imparts high stability to the Pd–Cu hydride structure. The obtained PdCu 0.2 H 0.43 catalyst exhibits a small overpotential of 28 mV at 10 mA/cm 2, a low Tafel slope of 23 mV/dec, and excellent HER durability due to its appropriate hydrogen adsorption free energy and alleviated metal dissolution rate.