Oxygen vacancies induced by Ce3+/Ce4+ doping mediate the formation of Bi0/Bi2O3/Bi2O2.75 nanosheets for visible light-driven photocatalytic degradation of lignin

•Oxygen vacancies induced by Ce doping mediate the formation phase transition rearrangement of δ-Bi2O3 to form tetragonal phase Bi2O2.75.•In-situ reduction of Bi3+ produces Bi0 to prepare S-type heterojunction Bi0/Bi2O3/Bi2O2.75 ultrathin nanosheets.•The S-type charge transfer mechanism of Bi0/Bi2O3/Bi2O2.75 heterojunction has been analyzed through experiments and DFT calculations.