Preferential growth and electron trap synergistically promoting photoreduction CO2 of Tm ion doping bismuth titanate nanosheets

Abstract

In this study, we prepared two-dimensional Bi₄Ti₃O₁₂ nanosheets doped with rare earth ions. The experimental results show that Bi_4-xTm_xTi₃O₁₂ exhibits the highest reduction performance among various rare earth doped Bi₄Ti₃O₁₂ materials, with a CO yield of 7.25 μmol g^-1h^-1. Furthermore, a delayed reaction in Bi_3.97Tm_0.03Ti₃O₁₂ is observed upon a cessation of light irradiation. Theoretical calculations reveal that the introduction of Tm ion not only reduces the surface energy of (001) plane and make it preferential growth in Bi₄Ti₃O₁₂, but also brings the intervening energy level of Tm ion (4f and 4d mixed orbital), which is closer to the conduction band of Bi₄Ti₃O₁₂ and facilitates charge carrier accumulation in trap states. The electrons retained in the shallow traps promote the hysteresis reaction following a cessation of illumination. This work provides further insights into elucidating precise reduction reaction mechanisms underlying rare earth dopant on photocatalysts. This research provides enhanced insights into unraveling the precise reduction reaction mechanisms influenced by rare earth dopants in photocatalysts.

Keywords: Layered perovskite; Photocatalytic reduction of CO(2); Rare earth dopant; Shallow trap; Surface energy.