Chemical bonding interface in Bi2Sn2O7/BiOBr S-scheme heterojunction triggering efficient N2 photofixation

Rapid recombination of interfacial charges is considered to be the main obstacle limiting N2 photofixation. It is urgent but challenging to develop a precise and stable strategy to steer charge transfer. Herein, oxygen-vacancy-rich Bi2Sn2O7 (BSO) are designed to be mounted on ultrathin BiOBr (BOB) with Bi-O vacancy pairs to construct the chemical bonding interface. The Bi and O atoms exposed by defects form the new Bi-O bonds to strengthen the built-in electric field, thus constructing the Bi2Sn2O7/BiOBr (BSOB) S-scheme heterojunction. During irradiation, electrons in CB of BOB rapidly recombine with holes in VB of BSO, and the electrons enriched in CB of BSO endow the strong reduction power for BSOB to trigger efficient photocatalytic nitrogen reduction. The ammonia yield of BSOB can reach 459.04 μmol g−1 h−1 in pure water. This work provides atomic-scale insights for the construction of efficient S-scheme heterojunction photocatalyst based on chemical bonding interface.