Delafossite ABO2 for photocatalysis: Current status, challenges, and future prospects from fundamental research to practical applications

Delafossite ABO2 materials, characterized by their layered superlattice structure of alternating O–A–O dumbbell layers and BO6 octahedra, exhibit exceptional light-harvesting capabilities and tunable electronic bandgaps (0–5.0 eV), establishing a unique platform for photocatalytic applications. This review systematically examines recent progress in the fundamental research and engineering applications of these materials. Mechanistic insights focus on how electronic structure features govern redox reaction kinetics, while material design strategies—including mechanochemical synthesis and elemental doping—are analyzed for their role in modulating microstructure and performance. Applications in environmental remediation (e.g., pollutant degradation) and energy conversion (e.g., photocatalytic water splitting, CO2 reduction) are critically evaluated in terms of efficacy, limitations, and preliminary techno-economic potential. Current bottlenecks—such as rapid charge recombination, limited stability under operational conditions, and scalability challenges in synthesis—are discussed in the context of practical deployment. To overcome these barriers, multiscale innovations involving heterostructure engineering, atomic-scale doping, and in situ protective layers are highlighted. Looking forward, this review emphasizes emerging pathways for advancing delafossite-based systems, including AI-aided material discovery, hybrid photoelectrochemical design, and—critically—comprehensive techno-economic assessment to evaluate economic viability, manufacturing costs, and environmental impact. Such holistic analysis will be essential to guide the transition of delafossite photocatalysts from laboratory research toward scalable, economically feasible sustainable energy and environmental solutions.