Catalytic co-liquefaction of microalgae + corn straw over K3PO4+γ-Al2O3 supported Fe and Ni mono- / bimetallic in-situ composite catalysts for the production of liquid biofuel

•K3PO4 + γ-Al2O3 supported Fe / Ni metallic in-situ composite catalysts were prepared.•Synergistic interaction between K3PO4 and Fe-Ni notably enhance catalytic activity.•K3PO4-Fe-Ni/γ-Al2O3 provided the highest yield and energy recovery in biocrude.•K3PO4-Fe-Ni/γ-Al2O3 showed a larger portion (57.18 wt%) of lighter oil components.•The probable reaction pathway and mechanism of catalytic co-HTL were proposed.