Determining Key Parameters of n‐ and p‐Type 3C‐SiC Photoelectrodes for Water‐Splitting Application

Photoelectrochemical water splitting is a promising route to sustainable hydrogen production, but it requires semiconductor electrodes with optimal bandgap, proper band‐edge alignment to the water redox potentials, and high corrosion resistance. Cubic silicon carbide (3C‐SiC) is a compelling candidate due to its near‐ideal bandgap energy and excellent chemical stability. Here, we systematically characterize SiC photoelectrodes comprising of n‐type and p‐type 3C‐SiC thin films grown on Si substrates of matching dopant type. Linear‐sweep voltammetry and electrochemical impedance spectroscopy yield the key photoelectrochemical parameters including the flat‐band potential and open‐circuit potential. Ultraviolet photoelectron spectroscopy and low‐energy inverse photoelectron spectroscopy provide the valence‐band maximum, conduction‐band minimum, Fermi level positions, and bandgap energies. Together, these results elucidate the detailed energy band landscapes for both n‐ and p‐3C‐SiC/electrolyte interfaces. The energy diagrams explain the observed behavior with and without illumination, confirming that n‐doped 3C‐SiC functions as efficient photoanode for oxygen evolution while p‐doped 3C‐SiC acts as photocathode for hydrogen evolution in neutral aqueous electrolyte. Establishing these quantitative band‐edge alignments provides a blueprint for designing durable, bias‐free tandem PEC architectures. Given the scalability and stability of SiC, these insights advance pathways toward cost‐effective, large‐scale green‐hydrogen production with a reduced environmental footprint.