Pd hydride metallene aerogels with lattice hydrogen participation for efficient hydrogen evolution reaction.

Hydrogen adsorption and desorption in single-phase catalysts often occur at a single catalytic site based on the traditional hydrogen evolution reaction (HER) pathway, which makes it difficult to break the limitation entailed by the Sabatier principle. Herein, β-Pd hydride metallene (β-PdHene) aerogels are synthesized as advanced HER catalysts. A lattice hydrogen-involved mechanism is reported to separate adsorption and desorption sites, which is thermodynamically favorable compared to the traditional reaction pathway. In situ differential electrochemical mass spectrometry and theoretical calculations reveal that lattice hydrogen as additional active sites directly participate in the HER process. Consequently, β-PdHene aerogels exhibit a low overpotential of only 20 mV at 10 mA cm and remarkable HER stability, which are even comparable to commercial Pt/C. Our work opens an avenue to rationally develop highly active HER catalysts, bypassing the design limitations of catalysts under traditional mechanisms.