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

The differences in Fermi levels (Ef) 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 (Ov) supported by carbon (Ru/MxOy@C, M = V, Nb, Ta) was fabricated. Since the Ef of MxOy is higher than that of Ru, an adjustable BEF directed by MxOy towards Ru is generated at the interface. The electron-deficient MxOy can dissociate H2O effectively, and the electron-rich Ru favors the desorption of hydrogen intermediates. Both experimental and theoretical results confirm the above conclusions. The Ru/Ta2O5@C demonstrates superior activity than Pt/C. This work provides new design principles toward efficient electrocatalysts for hydrogen evolution reaction (HER).