This manuscript reports the synergic effect for overall water splitting of N-doped defective graphenes obtained from the pyrolysis of biomass wastes, upon deposition at 1 wt% of Al-doped SrTiO3 containing RhCrOx nanoparticles (RhCrOx/STO:Al) as co-catalyst, exhibiting a photocatalytic activity of 153 mmol of H-2 per g of total photocatalyst and 74 mmol/g of O-2 at 24 h irradiation with UV-vis light reaching an incident photon to hydrogen efficiency of 0.67% at 360 nm. This hybrid N-doped defective graphene-RhCrOx/STO:Al photocatalyst was stable in 4 consecutive photocatalytic runs. The obtained results indicate that just a small amount of RhCrOx/STO:Al acting as co-catalysts supported on N-doped defective graphene is sufficient to enhance significantly its photocatalytic activity, making N-doped graphene suitable for overall splitting.