“Optoiontronic” Insights into the Water-Splitting Reaction Mechanism in the Cu(In,Ga)Se₂ Photoelectrode/Electrolyte Interface

This study introduces the “optoiontronic” perspective on the mechanism of water-splitting reactions in photoelectrode/electrolyte interfaces, which is an approach that integrates optoelectronic and ionic dynamics by including the interaction between the light-induced electrons and hydrogen ions (H⁺). Considering the Cu(In,Ga)Se₂ (CIGS) photoelectrode/electrolyte interface with Ni-based cocatalysts (an ideal semiconductor for hydrogen production), the results indicated the traditional approaches based on either optoelectronic or ionic perspectives may overlook critical mechanisms. Furthermore, the results suggested that the rate of the reaction between light-induced electrons and H⁺ in the CIGS photoelectrode/electrolyte interface enhanced by the Ni-based cocatalysts was greater than that of surface recombination from the “optoiontronic” perspective. Including interactions between light-induced electrons and H⁺ in the analysis of the photoelectrode/electrolyte interface may constitute a breakthrough in understanding the reaction mechanism of water splitting.