Background: The hydrogen evolution reaction is a crucial step in electrochemical water
splitting to generate molecular hydrogen with high purity, but it usually suffers from a sluggish reaction
kinetics in alkaline media because of additional water dissociation and/or improper adsorption
energy of reactive hydrogen intermediates. It is desirable to design highly active and robust nonprecious
electrocatalysts as alternatives to state-of-the-art commercially available Pt/C catalysts for
large-scale hydrogen production via water-alkali electrolysis.
Methods: We developed monolithic nanoporous hybrid electrodes composed of electroactive
Mo@MoOx nanoparticles, which are seamlessly integrated on hierarchical nanoporous Cu scaffold
(Cu/Mo@MoOx) by making use of a spontaneous phase separation of Mo nanoparticles and subsequently,
self-grown MoOx in chemical dealloying.
Results: Owing to the unique monolithic electrode architecture, in which the constituent Mo@MoOx
nanoparticles work as electroactive sites and the hierarchical nanoporous Cu skeleton serves as fast
electron-transfer and mass-transport pathways, the monolithic nanoporous Cu/Mo@MoOx hybrid
electrode exhibits superior electrocatalysis in 1 M KOH, with a low Tafel slope of 66 mV dec−1 and
outstanding stability. It only takes them ~185 mV overpotential to reach −400 mA cm−2, ~150 mV
lower than that of nanoporous Cu supported Pt/C.
Conclusion: The outstanding electrochemical performance and excellent structural stability make
nanoporous Cu/Mo@MoOx electrodes attractive alternatives to Pt/C catalysts in alkaline-based devices.