Cobalt and iron-exchanged LiLaTa₂O₇ layered perovskites and their applicability in sustainable photocatalytic processes

Solar energy catalysis remains an environmentally friendly technology that effectively addresses numerous global issues, including pollution removal, CO₂ reduction or clean hydrogen fuel generation. Dion-–acobson-type layered perovskites are applicable semiconductors for sustainable photocatalytic processes, particularly for the photocatalytic H₂ production as well as for the degradation of organic pollutants. Their effectiveness arises from the capacity to adjust their electronic and structural properties through multiple modification methods, including ion exchange processes. For an efficient photocatalytic system, its activity is decided by factors such as the band gap, crystallinity, morphology, specific surface area, and defects. Therefore, the strict control of the synthesis parameters affecting these properties is decisive.

This study focuses on the synthesis, structure, and properties of perovskite-related layered transition oxyhalides of the type (MeCl)LaTa₂O₇ (Me = Co, Fe) along with their assessment for sustainable photocatalytic processes (e.g. H₂ generation from water splitting). The development of (MeCl)LaTa₂O₇ type functional materials was achieved through ion-exchange reactions, in which the starting compound, LiLaTa₂O₇, was combined with a two-fold molar excess of MeCl₂, under mild conditions (350 °C, 3 h). The XRD analysis confirms the successful incorporation of Co and Fe species within the perovskite-type LaTa₂O₇ layers. The intercalation of transition metal species influences the electronic band structure of materials by creating a new, higher-energy valence band and reducing their band gap values. The preliminary photocatalytic experiments for water splitting, conducted in the absence of a sacrificial reagent, have demonstrated the potential activity of these layered-perovskite-related materials. Subsequent research will aim to enhance reaction rates through the addition of various co-catalysts and understanding the reaction mechanisms, thereby making these materials suitable for practical applications.