Photoelectrochemical Pathways to Green Hydrogen: Analysis, Review, and Foresight

Abstract

The current dynamics of decarbonization reveal structural limitations of existing hydrogen production models. Techno-economic assessments indicate that energy consumption remains the primary factor determining the cost of green hydrogen, while the pace of electrolyzer capacity expansion remains insufficient compared with the trajectories required to achieve carbon neutrality. Despite the increase in installed electrolyzer capacity from approximately 0.1 GW in 2020 to about 1.75 GW in 2023, a significant share of announced projects has not reached the stage of final investment decision, and infrastructure constraints persist.

Photoelectrochemical water splitting represents an alternative configuration that integrates semiconductor light absorption and electrochemical water splitting within a single system. Unlike centralized electrolysis schemes that require developed logistics for hydrogen storage and transportation, PEC architectures enable localized hydrogen generation, thereby reducing supply-chain vulnerabilities highlighted in studies on hydrogen infrastructure reliability.

This study presents a systematic analysis of the evolution of PEC technologies by integrating materials science data, bibliometric indicators, and patent activity dynamics. The relationship between threshold values of solar-to-hydrogen efficiency, material stability limitations, and the innovation trajectories of oxide, nitride, chalcogenide, and hybrid photoelectrodes is examined. A prospective roadmap to 2035 is proposed, emphasizing strategies for replacing noble metals, compatibility with industrial manufacturing, and integration into distributed hydrogen infrastructure. PEC is considered a long-term complementary technology within the emerging architecture of the hydrogen energy system.