Ammonia is a suitable hydrogen carrier with each molecule accounting for up to 17.65% of hydrogen by mass. Among various potential ammonia production methods, we adopt the photoelectrochemical (PEC) technique, which uses solar energy as well as electricity to efficiently synthesize ammonia under ambient conditions. In this article, we report MoS 2 @La 2 Zr 2 O 7 heterostructures designed by incorporating twodimensional (2D)-MoS 2 nanoflakes on La 2 Zr 2 O 7 nanofibers (MoS 2 @LZO) as photoelectrocatalysts. The MoS 2 @LZO heterostructures are synthesized by a facile hydrothermal route with electrospun La 2 Zr 2 O 7 nanofibers and Mo precursors. The MoS 2 @LZO heterostructures work synergistically to amend the drawbacks of the individual MoS 2 electrocatalysts. In addition, the harmonious activity of the mixed phase of pyrochlore/ defect fluorite-structured La 2 Zr 2 O 7 nanofibers generates an interface that aids in increased electrocatalytic activity by enriching oxygen vacancies in the system. The MoS 2 @LZO electrocatalyst exhibits an enhanced Faradaic efficiency and ammonia yield of approximately 2.25% and 10.4 μg h −1 cm −2 , respectively, compared to their corresponding pristine samples. Therefore, the mechanism of improving the PEC ammonia production performance by coupling oxygen-vacant sites to the 2D-semiconductorbased electrocatalysts has been achieved. This work provides a facile strategy to improve the activity of PEC catalysts by designing an efficient heterostructure interface for PEC applications.