Modulating the interfacial built-in electric field in oxygen vacancies-enriched Ru/MxOy@C (M = V, Nb, Ta) ordered macroporous heterojunctions for electrocatalytic hydrogen production.

[Display omitted] • The difference in Fermi level between Ru and M x O y results in electron transfer. • The BEF created by the charge transfer facilitates the transfer of the charge. • The electronic structure of Ru was regulated by M x O y. • The interaction between Ru and M x O y improves the stability and activity of Ru. • The porous structure of the catalysts promotes the diffusion of electrolyte. The differences in Fermi levels (E f) can drive the electrons flow across the metal/semiconductor interfaces, resulting in a built-in electric field (BEF) to enhance charge migration. Meanwhile, the induced electron-rich/deficient counterparts can modulate the active sites and reaction steps. In this work, a three-dimensionally ordered macroporous (3DOM) heterostructure with oxygen vacancy (O v) supported by carbon (Ru/M x O y @C, M = V, Nb, Ta) was fabricated. Since the E f of M x O y is higher than that of Ru, an adjustable BEF directed by M x O y towards Ru is generated at the interface. The electron-deficient M x O y can dissociate H 2 O effectively, and the electron-rich Ru favors the desorption of hydrogen intermediates. Both experimental and theoretical results confirm the above conclusions. The Ru/Ta 2 O 5 @C demonstrates superior activity than Pt/C. This work provides new design principles toward efficient electrocatalysts for hydrogen evolution reaction (HER). [ABSTRACT FROM AUTHOR]