Probing the Energetics of Model Photocatalyst/Co-Catalyst/Water Junction Interfaces

Photocatalytic water splitting is a promising approach for large-scale hydrogen production. However, the low efficiency of photocatalysts hinders their usage in practical applications. Understanding the energetics and kinetics at the liquid junction provides valuable insights into the operation of photocatalysts, and is therefore indispensable for improving the efficiency of photocatalyst systems. In this work, we first present a kinetic model for semiconductor/two-redox liquid junctions. We then show a characterization framework to simulate photocatalysts’ operation by using model photoelectrodes (SrTiO₃ grown by Molecular Beam Epitaxy). We used ohmic back contacts to directly probe the quasi-fermi level at the liquid junction under operating conditions by measuring open-circuit potentials. Finally, we developed a semiconductor/liquid junction model based on kinetics and reversibility, using COMSOL Multiphysics package, to simulate semiconductor/two-redox liquid junctions and validate our experimental results.