Acid-inducing {110}/{121} facet junction formation boosting the selectivity and activity of CO2 photoreduction by BaTiO3 nanoparticles

Abstract

The exposure of anisotropic crystal facets of photocatalysts is an effective method to address the issue of the directional transfer of photoexcited carriers. However, the facet effect of BaTiO₃ is random and the study of photocatalytic CO₂ reduction is in its infancy. Herein, we develop an unprecedented polyhedral BaTiO₃ nanoparticle with oriented growth of {110} facets via a hydrothermal and acid-etching process. Compared to the original octahedral BaTiO₃, polyhedral BaTiO₃ nanoparticles with {110}/{121} facet junctions have significantly enhanced photocatalytic activity for the evolution of CO and CH₄. BaTiO₃ nanoparticles with {110}/{121} binary facet junctions exhibit a photocatalytic activity with maximal CO and CH₄ yields of 3.77 μmol g⁻¹ and 3.61 μmol g⁻¹, respectively, while the original octahedral BaTiO₃ only shows CO and CH₄ evolution of 1.80 μmol g⁻¹ and 2.09 μmol g⁻¹. Density functional theory calculations and photo-deposition results reveal that the band energy of a BaTiO₃ nanoparticle with a {110}/{121} binary facet junction provides a cascade path for efficient charge flow compared to octahedral BaTiO₃ with {121} facets. Molecular dynamics calculation explores the path of CO₂ reduction reaction. This work gives an in-depth insight into a crystal facet junction with a cascade path and its selective CO₂ reduction reactions for efficient photocatalysts.