<p>A series of Co–Cu catalysts supported on Al₂O₃-g-C₃N₄ hybrid materials with varying g-C₃N₄ content (0–100 wt%) were prepared via a simple wet impregnation method and evaluated for higher alcohol synthesis (HAS) under mild conditions. Structural analysis by PXRD confirmed the formation of Co₃O₄ and CuO phases, while microstrain calculations revealed that moderate incorporation of g-C₃N₄ (15 wt%) introduces beneficial lattice distortion, creating defect-rich environments and promoting the formation of active Cu⁺-Co⁰ interfacial sites. The BET results show that catalyst (Cat-2) exhibits the highest surface area (152&#xa0;m²&#xa0;g⁻¹) and has a suitable pore structure providing sufficient active metal dispersion. This is well supported by SEM–EDX mapping, which illustrates an even distribution of Co and Cu across the hybrid support whereas higher g-C₃N₄ levels induce larger particle agglomeration. The H₂-TPR profiles of these catalysts demonstrate Cat-2 has a greater reducibility than other catalysts tested, as indicated by comparatively lower reduction temperatures. The aforementioned characteristics provide favourable catalytic properties, as lattice strain, well-dispersed bimetallic sites, and the g-C₃N₄/Al₂O₃ support function synergistically to improve CO activation, facilitate C–C bond formation, and hold oxygenate intermediates, subsequently improving the overall HAS reaction. As a result, the optimized catalyst shows improved selectivity toward C₂₊ alcohols while suppressing undesired methanation. This study highlights how careful tuning of support composition and defect structure can effectively guide catalyst design for efficient higher alcohol synthesis.</p> Graphical Abstract <p>2D g-C₃N₄ thermodynamic steering in Cu-Co/Al₂O₃ catalysts enhances CO insertion and boosts higher alcohol selectivity under mild reaction conditions for syngas conversion.</p> <p></p>