Interfacial engineering of a nanofibrous Ru/Cr₂O₃ heterojunction for efficient alkaline/acid-universal hydrogen...

Interfacial engineering of a heterostructured electrocatalyst is an efficient way to boost hydrogen production, yet it still remains a challenging task to achieve superior performance at ampere-grade current density. Herein, a nanofibrous Ru/Cr₂O₃ heterojunction is prepared for alkaline/acid-universal hydrogen evolution. Theoretical calculations reveal that the introduction of Cr₂O₃ modulates the electronic structure of Ru, which is beneficial for *H desorption, resulting in a superior HER performance at ampere-grade current density. Accordingly, the resultant Ru/Cr₂O₃ catalyst presents an ultra-low overpotential of only 88 mV and a long-term stability of 300 h at 1 A cm^-2 in 1 M KOH. Furthermore, it also exhibits a small overpotential of 112 mV and steadily operates for 300 h at 1 A cm^-2 in 0.5 M H₂SO₄. The catalyst outperforms not only the benchmark Pt/C catalyst but also most of the top-performing catalysts reported to date. This study offers a novel conceptual approach for designing highly efficient electrocatalysts that hold significant promise for industrial-scale water splitting applications.