Unveiling the photocatalyst surface poisoning during water splitting: mechanisms, theoretical modeling and anti-poisoning strategies

Abstract

Photocatalytic water splitting has emerged as a promising approach for sustainable hydrogen production. However, the long-term efficiency and stability of photocatalysts are significantly hampered by the catalyst poisoning critical challenge that impedes practical applications. This comprehensive review provides an in-depth analysis of the mechanistic aspects of photocatalyst poisoning in water splitting systems. The discussion encompasses a wide range of deactivation pathways, including surface fouling by reaction intermediates, adsorption of inorganic ions (e.g., phosphate, carbonate, and metal ions), structural degradation under prolonged irradiation, and irreversible binding of sacrificial agents or by-products. Special emphasis is placed on understanding how these poisons interact with active sites, alter charge separation dynamics, and affect photocatalytic activity at the molecular and atomic levels. Advanced characterization techniques such as in situ spectroscopy, surface analysis, and theoretical modeling are reviewed for their role in elucidating these mechanisms. Additionally, strategies to mitigate poisoning such as surface modification, heterojunction engineering, co-catalyst optimization, and regeneration methods are critically evaluated. This review highlights the need for mechanistic insight to design robust and poison-resistant photocatalysts, ultimately contributing to the development of efficient and durable systems for solar-driven water splitting.