Oxygen vacancy and Van der Waals heterojunction modulated interfacial chemical bond over Mo2C/Bi4O5Br2 for boosting photocatalytic CO2 reduction

The establishment of heterojunctions between phase interfaces is an important strategy to enhance catalytic activity, but the behavior of charge transfer and exciton dissociation is unsharpness and significant. Here, a Van der Waals heterojunction (VDWH) of Mo 2 C/Bi 4 O 5 Br 2 composite with oxygen vacancies (BM) was synthesized via a facile method. Various experimental results and density functional theory calculations demonstrated that the compact VDWH and unsaturated oxygen vacancy induced interfacial Mo-O bonds to modulate surface electronic structure. Consequently, the electron extracted from the exciton formed a strong internal electric field, which boosted the dissociation of the excitons and charge transfer via the electron transfer channel of the Mo-O bond. Therefore, the BM shows excellent CO 2 reduction performance (1277.4 µmol g -1 h -1 ) and stability without using sacrificial agents and cocatalysts, which is about 6 times of Mo 2 C/Bi 4 O 5 Br 2 . This work not only gives deep insights into charge separation in VWDH and oxygen vacancy but also provides an efficient photocatalyst for efficient green energy conversion. • The Bi 4 O 5 Br 2 and Mo 2 C VDWH with oxygen-rich defects was prepared by the self-assembly method. • The interfacial Mo-O bonds for modulating surface electronic structure. • The Mo-O bonds could boost the excitons dissociation and charge transfer. • BM materials exhibited excellent photocatalytic activity and stability.