This PDF file includes:

• fig. S1. Powder XRD patterns of the crystalline BSCF perovskite target.
  
• fig. S2. Surface morphology obtained by AFM on the top of Ni foil.
  
• fig. S3. SEM image of the amorphous BSCF nanofilm and the respective energy-dispersive x-ray spectrum.
  
• fig. S4. SEM images of the film/substrate interface on the top of silicon wafer.
  
• fig. S5. Basic characterizations and OER activity of bulk IrO₂.
  
• fig. S6. Tafel slopes for mass activities of amorphous BSCF on Ni foil substrates.
  
• fig. S7. Ni 2p XPS.
  
• fig. S8. XPS and OER results of reduced Ni-based nanofilms.
  
• fig. S9. OER activities of Ni oxide–based nanofilms.
  
• fig. S10. XPS results of ITO-based nanofilms.
  
• fig. S11. Mass activities for BSCF-ITO heterostructures.
  
• fig. S12. Tafel plots.
  
• fig. S13. Stability tests of nanofilms.
  
• fig. S14. Stability tests of Ni foil and Ni foam.
  
• fig. S15. OER activity for the 38.7 and 154.8 μg cm⁻² BSCF–Ni foam heterostructure electrodes in a 1.0 M KOH solution.
  
• fig. S16. Photograph of a water-splitting device.
  
• table S1. Comparison of the mass activities of the thin-film heterostructures to other recently reported catalysts for the OER in an alkaline solution.
  
• table S2. Comparison of the overpotentials to obtain 10 mA cm⁻²_film for the ITO-based heterostructures and the Ni foil–based heterostructures.
  
• table S3. Comparison of the performance of the water-splitting catalysts in a 1.0 M KOH solution.
  
• Legend for movie S1
  
• References (33–47)

Download PDF

Other Supplementary Material for this manuscript includes the following:

• movie S1 (.mp4 format). Video of a water-splitting device.