In-situ anion exchange based Bi2S3/OV-Bi2MoO6 heterostructure for efficient ammonia production: A synchronized approach to strengthen NRR and OER reactions

•The Bi2S3/OV-Bi2MoO6 S-scheme heterojunction is constructed using a simple in-situ anion exchange process enabling oxygen vacancy (OV) abundant Bi2MoO6 microspheres with surface deposited Bi2S3.•The as-fabricated Bi2S3/OV-Bi2MoO6 functioned as an effective photocatalyst to convert N2-to-NH3 under mild conditions without any sacrificial agent.•The photocatalytic NH3 production rate reached 126 μmol gcat−1 under visible light for 2.5 h with 2% Bi2S3/OV-Bi2MoO6 photocatalyst, which was 8 fold higher than Bi2MoO6.•The S-scheme heterojunction accelerated the e−/h+ pairs spatial separation and accumulation on the Bi2S3 and Bi2MoO6 side, respectively, thus simultaneously strengthening both OER and NRR half-reactions.