A comprehensive overview of reactor design and operating conditions for photoelectrochemical water splitting

Over the past few decades, there has been a growing scientific interest in photoelectrochemical (PEC) water splitting as a direct and sustainable route for green hydrogen production using only sunlight. Today major advances have been achieved in enhancing photoelectrode efficiency and stability. However, progressing the system toward practical implementation and increasing the TRL from 3 to 5 requires innovative cell designs and optimized operating conditions. Highly compact and low-cost PEC cells are needed for large scale application, whereas high versatility is expected for lab-scale test cells. Moreover, robust materials capable of withstanding elevated temperatures, pressures, and concentrated solar irradiation are necessary. This review presents a comprehensive overview of operating parameters, reactor materials, and cell designs, highlighting their impact on performance and durability. The clear focus on integrated reactor design and operation, identifies pathways for advancing the PEC technology to industrially relevant scale. • Innovative photoelectrochemical reactor designs are presented and evaluated. • Suitable operating conditions for efficient water splitting are summarized. • An overview about reactor material requirements is given.