• Co3O4/graphdiyne heterostructured nanowires (Co3O4/GDY NWs) were synthesized via a simple two-step process, achieving a high NH3 yield rate of 0.78 mmol h−1 cm−2 and a Faraday efficiency of 92.45% at −1.05 V vs. RHE.
• The heterointerface features sp-C―Co bonds and incomplete charge transfer between GDY and Co, providing a continuous electron supply that enhances the nitrate reduction reaction (NtRR).
• This work demonstrates a general approach for constructing heterostructures that enable efficient ammonia production from wastewater under ambient conditions, offering a sustainable alternative to the energy-intensive Haber-Bosch process.
• The Co3O4/GDY heterostructure shows improved electrical conductivity and increased active sites, addressing the challenges of the complex eight-electron nitrate-to-ammonia conversion.