Novel n-n heterojunction nanocomposite constructed by g-C3N4 nanosheets and Cu3V2O8 nanoparticles: Facile fabrication and improved photocatalytic activity for N2 fixation under visible light

•A novel g-C3N4 nanosheet/Cu3V2O8 nanocomposite constructed by calcination- method.•The prepared nanocomposite exhibited improved activity on photocatalytic N2 fixation under visible light irradiation.•The photocatalytic efficiency of g-C3N4 nanosheet/Cu3V2O8 nanocomposite was 7.7, 2.6, and 4.3 times higher than that of g-C3N4, g-C3N4 nanosheet, and Cu3V2O8.•Electron-hole pair separation and transfer pathways for g-C3N4 nanosheet/Cu3V2O8 nanocomposite based n-n heterojunction formation were discussed.•Stability and reusability of photocatalyst were confirmed in consecutive cycles