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.