Synergistic effect of Li, La co-doping on photocatalytic activity of BaTiO3 ferroelectric material for effective degradation of toxic NOx for environmental remediation

Abstract

We investigated the synergistic effects of Li, La-doping and co-doping on the A-site of perovskite BaTiO3 microstructure as a catalyst for the removal of toxic NOx for environmental remediation. The Rietveld refinement of XRD and Raman analysis confirmed that at room temperature, the ceramic samples possessed a pure-tetragonal perovskite structure, with P4mm space group. SEM images revealed a denser microstructure with reduced grain size on Li, La doping in BaTiO3. XPS results confirmed the coexistence of Li and La as doping elements into BaTiO3 lattice. EPR and PL spectra demonstrate the presence of Ti and Ba vacancies as well as defects. According to the DRS results, the absorption edge of the co-doped sample was blue-shifted. In frequency-dependent dielectrics, the co-doped sample exhibits the greatest rise in dielectric permittivity. Impedance measurement demonstrates the fastest rate of charge transport in Ba0.98Li0.01La0.01TiO3. Similarly, Li and La incorporation into BaTiO3 significantly reduced the recombination extent of charge carriers as evidenced by the PL. Under UV light, the photocatalytic NOx degradation with Ba0.98Li0.01La0.01TiO3 achieved a remarkable 44 % efficiency during 60 min. This enhancement is associated with improved charge carrier separation at the interface between the ferroelectric surfaces. Only a marginal decrease in photocatalytic activity occurred after four consecutive runs. A reasonable photocatalytic mechanism for the degradation of NOx over Ba0.98Li0.01La0.01TiO3 is proposed. This study's findings can inspire the design and synthesis of rare earth and alkali metal ion co-doped photocatalysts with built-in electric fields of a ferroelectric material for efficient NOx removal from the environment.