Photogenerated charge separation and recombination path modification in monocline Lu2WO6via lattice transition and Bi-O antibonding states.

Abstract

Monoclinic Lu2WO6 undergoes diphase-to-perovskite BiLuWO6 transition via selective occupancy of Bi in three Lu sites. The transformation mechanism, process, and structure stabilities are revealed by variable cell nudged elastic band method, video, and phonon spectrum. Lattice transition brings about photogenerated charge separation in BiLuWO6. This is verified by indirect band gap transition, high electron migration rate, weak exciton binding energy, large photocurrent response, and small impedance. The electron-hole life time is elongated to produce abundant superoxide and hydroxyl radicals for the degradation of rhodamine B and phenol molecules. Bi-O antibonding states serve as immediate energy levels to change the recombination path, inducing 340 nm excitation band and 510 nm green light emission of Lu2WO6. Furthermore, multicolor emission of 1 at% Bi3+ + RE3+ (RE = Sm/Eu/Dy)-codoped Lu2WO6 is acquired via synergistic modification of the Bi-O antibonding state and RE3+ 4f states. Thus, the photogenerated charge motion in Lu2WO6 is tuned to expand application fields.