All-solid Z-scheme Bi/γ-Bi2O3/O-doped g-C3N4 heterojunction with Bi as electron shuttle for visible-light photocatalysis

Abstract

In order to broaden the spectral response range of graphitic carbon nitride (g-C 3 N 4 ) and improve its visible-light catalytic activity, the method of ethanol-assisted solvo-thermal pretreatment and subsequent polymerization was used to prepare Bi/γ-Bi 2 O 3 nanoparticles modified O-doped g-C 3 N 4 (Bi/γ-Bi 2 O 3 /EtCN). During the polymerization of g-C 3 N 4 , oxygen doping brought about a richer pore structure , while ethanol and urea promoted the formation of sub-stable γ-Bi 2 O 3 , and most importantly, these reactions were achieved simultaneously to successfully fabricate the all-solid Z-scheme structure. The obtained Bi/γ-Bi 2 O 3 /EtCN showed much higher activity in the visible-light photocatalytic degradation of bisphenol A (BPA) than that of g-C 3 N 4 and EtCN, where the degradation rate of 0.03Bi/γ-Bi 2 O 3 /EtCN was 15.67 times higher than that of g-C 3 N 4 , showing excellent visible photocatalytic performance. The improvement of the activity of Bi/γ-Bi 2 O 3 /EtCN mainly caused by the formation of all-solid Z-scheme heterojunction between γ-Bi 2 O 3 and EtCN with Bi as the electron shuttle, which broadened the light absorption range of the catalyst, promoted the effective separation of electron-hole pairs. It was also found that •O 2 − played a major role and h + played a secondary role during BPA degradation process using 0.03Bi/γ-Bi 2 O 3 /EtCN as the photocatalyst , which confirmed the mechanism of Z-scheme heterojunction. • A novel all-solid Z-scheme Bi/γ-Bi 2 O 3 /O-doped g-C 3 N 4 heterojunction was prepared. • Bi/γ-Bi 2 O 3 /O-doped g-C 3 N 4 exhibited a much higher activity than bulk g-C 3 N 4 . • Bi plays a role as electron shuttle, leading to the formation of •O 2 - .