Immobilized photocatalyst devices for scalable overall water splitting

Immobilized photocatalyst devices for overall water splitting (OWS) have emerged as a promising strategy for practical hydrogen production. Compared with traditional powder suspension systems, they offer great advantages, including scalability, facile recovery/replacement of photocatalysts, and the elimination of extra dispersion operations. Over the past decade, significant progress has been achieved in this field, especially in material screening, device construction, and system integration for scalable applications. However, up until now, there have been no related reviews focusing on this topic. This review aims to fill this gap by providing a comprehensive and structured overview of the immobilized photocatalyst devices for efficient OWS. Firstly, the basics of OWS process, including one-step and two-step photoexcitation mechanisms, are elaborated. Subsequently, recent advances in immobilized photocatalyst devices for scalable OWS via these two different approaches are summarized, based on which various solid-state electron mediators are classified and exemplified. The essential structure-performance relationship is also analyzed and revealed. Finally, the future prospects and challenges in this field are proposed and discussed.