Effects of activation overpotential in photoelectrochemical cells considering electrical and optical configurations

Photoelectrochemical cells (PECs) are a promising option for directly converting solar energy into chemical energy by producing hydrogen (H₂) gas, thus providing a clean alternative to consuming fossil fuels. H₂ as fuel is free from any carbon footprints and negative environmental impacts. Therefore, the H₂ production, especially directly using sunlight in PECs, is critically important for the rapidly growing energy demand of the world. Although promising, PECs are inefficient and must overcome a few inherent losses in producing H₂-the most important being the activation overpotential ($$) required for splitting water. This work analyzes the impact of $$ on solar-to-fuel efficiency ($$) and H₂ production rate (HPR). This work also discusses choosing appropriate photo-absorbing materials based on their energy bandgaps and suitable electrode pairs to achieve desired $$ and HPR for different electrical and optical PEC configurations. Significant changes are observed in $$ and HPR when $$ is considered in water splitting.