Boosting hydrogen evolution performance of nanoporous Fe-Pd alloy electrocatalyst by metastable phase engineering

Nanoporous Fe -Pd alloy with metastable face -centered cubic (fcc Fe -Pd) phase is prepared by electrochemical dealloying as an electrocatalyst for hydrogen evolution reaction (HER). The nanoporous fcc Fe -Pd alloy achieves an overpotential of 58 mV at 10 mA cm -2 in 1 M KOH, outperforming those of stable body -centered cubic Fe -Pd alloy (bcc Fe -Pd) and commercial Pt/C catalyst. Density functional theory calculation reveals that the metastable fcc structure can tailor the coordination environment and electronic structure of Pd active sites in Fe -Pd alloy. As a result, the d -band center of Pd active site shifts away from the Fermi level, which weakens the Pd -H interaction and reduces the energy barrier of water dissociation. In addition, the fcc Fe -Pd exhibits good mechanical properties, which maintains the catalytic performance in the deformation state. This work broadens the idea for designing and preparing HER catalysts via metastable phase structure design.