Unraveling the structural and morphological stability of oxygen vacancy engineered leaf-templated CaTiO3 towards photocatalytic H2 evolution and N2 fixation reactions

Abstract

The investigation of the structural and morphological stability of leaf-templated and oxygen vacancy engineered materials is of great importance along with the detailed study of catalytically active sites. In this work, oxygen vacancy engineered leaf-templated CaTiO₃ materials have been synthesized by using NaBH₄ as a reductant and the formation of oxygen vacancies was confirmed by using different spectroscopic and morphological techniques. Leaf-templated CaTiO₃ with the optimum amount of oxygen vacancies showed improved photocatalytic H₂ evolution and N₂ fixation abilities in comparison to pristine CaTiO₃. Density functional theory calculations suggested that the O-vacancies present in the TiO₂ plane played a crucial role in enhancing the photocatalytic performance than the O-vacancies present in the CaO plane of CaTiO₃. The optimized material showed good structural stability but with a loss in morphological features. It is concluded that the benefits of efficient light absorption by the three-dimensional morphology of leaf-templated semiconductor materials could not be utilized in the studied solid–liquid binary phase reactions. The enhanced photocatalytic performance could solely be attributed to the optimum oxygen vacancy sites, which promote the surface reactions and improve the separation of photogenerated charge carriers. This work is expected to provide a future direction in the smart design of application-oriented three-dimensional photocatalysts and other materials.