and long-term durability over 500 h. Our findings highlight the accelerated water-splitting performance on the oxygen-vacancy and interface modulated catalysts and shed light on the fabrication of advanced heterostructures for other catalytic reactions. Figure 7. a) The schematic illustration of the CrO x -Ni 3 N for overall water splitting. b) The performance of the CrO x -Ni 3 N//CrO x -Ni 3 N and Ni 3 N//Ni 3 N for overall water splitting, the inset image shows the comparison of the needed voltage to drive 10 mA cm −2 for the CrO x -Ni 3 N//CrO x -Ni 3 N and Ni 3 N//Ni 3 N. c) The Faradaic efficiency testing device and d) the corresponding Faradaic efficiencies for HER and OER. e) Long-term stabilities of the CrO x -Ni 3 N//CrO x -Ni 3 N and Ni 3 N//Ni 3 N at 50 mA cm −2 .