Engineered dual-interface MXene-integrated CoAlLa-LDH/TiO₂ ternary heterojunctions for highly selective photoreduction of CO₂ into renewable fuels

A well-designed trimetallic CoAlLa layered double hydroxide (CoAlLa-LDH), having a high number of active sites and oxygen defects, with multilayered Ti₃C₂ MXene and TiO₂ nanoparticles, was synthesized through heterojunction engineering to enhance CO₂ photoreduction. The strong interaction between a p-type CoAlLa-LDH and an n-type TiO₂, resulting in the formation of a distinctive S-scheme heterojunction, effectively promotes charge separation by reducing electron-hole recombination due to the multilayered Ti 3 C 2 MXenes. The photocatalytic conversion of CO₂ with H₂O resulted in the production of CO and CH₄ of 38.25 and 3.36 µmol in 4 h, respectively. The photocatalytic performance over optimized Ti₃C₂/CoAlLa-LDH/TiO₂ nanocomposite was 3.6 and 4.3 for CO and 2.64 and 3.28 for CH 4, respectively, higher than TiO₂ and LDH materials. The performance improvement was attributed to the construction of a heterostructure that offered abundant active sites, and the strong connection between nanomaterials, endorsing the generation of an electric field and hastening the transport of generated charge carriers. Furthermore, stability tests confirmed high stability of the CoAlLa-LDH/Ti₃C₂/TiO₂ nanocomposite over multiple cycles, demonstrating its long-term activation as a photocatalyst. This work not only provides a new pathway for designing highly efficient photocatalysts but also offers insightful guidance for future advancements in sustainable energy conversion and carbon-neutral technologies. • Lanthanum-doped CoAlLa-LDH/Ti 3 C 2 MXene for efficient photocatalytic CO 2 reduction. • S-scheme heterojunction of CoAlLa-LDH/TiO2 for enhanced charge carrier separation. • Ti 3 C 2 MXene as an electron reservoir boosting photocatalytic CO 2 -to-fuel conversion. • CoAlLa-LDH with unsaturated metal centres for improved CO 2 photoreduction. • Photocatalytic stability and quantum yield of CoAlLa-LDH/Ti 3 C 2 /TiO 2 nanocomposite.