Solar energy is the most abundant energy source available to humankind; this energy cannot be harnessed on demand, however, due to the variability of sunlight. Artificial photosynthesis offers a sustainable way to overcome that variability through the photocatalytic conversion of solar power into chemical fuels at a semiconductor–electrolyte interface. Although considerable progress has been made in simulating the bulk properties of semiconductors from first principles, much less has been done to address the electrochemical response of semiconductor–electrolyte interfaces under realistic environmental conditions. We present broadly applicable and highly transferable computational techniques to simulate semiconductor–electrolyte interfaces. By introducing a continuum model of the semiconductor and electrolyte regions surrounding the quantum-mechanical interfacial layer, our model enables the self-consistent determination of the electrical response of a semiconductor-solution interface, including the atomistic effects of charge trapping at interfacial surface states. Using this, we develop a new description of the semiconductor-solution interface allowing us to predict the electrical response, stability, and equilibrium Schottky barrier of a photoelectrode as a function of different surface chemistries. This allows researchers to optimize materials selection for both charge transport and stability, leading to more efficient and practical artificial photosynthesis systems.

Reference:

Campbell and Dabo, Physical Review B 95, 205308 (2017).