Facile fabrication of Pd–Cu2O hollow nanobowls for high-performance electrocatalytic hydrogen evolution in alkaline media

Hydrogen is widely regarded as a clean and efficient energy carrier with strong potential to support the global transition toward sustainable energy systems. Among the various production pathways, alkaline water electrolysis stands out for its scalability and environmental compatibility. In this study, Pd–Cu 2 O nanobowls were synthesized via a galvanic replacement reaction using Cu 2 O spheres as sacrificial templates. Structural and morphological analyses confirmed the formation of hollow, porous architectures composed of interconnected Pd and Cu 2 O nanodomains. XRD and Rietveld refinement revealed lattice contraction and reduced crystallite size upon Pd incorporation, suggesting strong interfacial interactions. The Pd–Cu 2 O nanobowls exhibited outstanding electrocatalytic performance toward the hydrogen evolution reaction (HER), outperforming both bare Cu 2 O spheres and commercial Pt/C under high current densities. Electrochemical tests demonstrated significantly lower overpotentials, a more favorable Tafel slope, and excellent operational stability. Despite a higher charge transfer resistance, the hybrid maintained superior HER activity, likely due to enhanced surface accessibility and the presence of catalytically active Pd domains. When compared to other Cu-based HER catalysts reported in the literature, the Pd–Cu 2 O nanobowls showed a compelling combination of activity, kinetics, and durability. These findings underscore the potential of galvanic replacement as a scalable route for designing hybrid nanostructures and position Pd–Cu 2 O as a promising alternative for sustainable hydrogen production.