Interface engineered cobalt sulfide/graphitic carbon nitride Ohmic junction for enhanced photocatalytic hydrogen...

The development of efficient non-noble-metal photocatalysts for solar-driven hydrogen production remains challenging due to inefficient charge separation and high energy barriers of the hydrogen evolution reaction (HER). In this work, metallic cobalt sulfide (Co₉S₈) cocatalysts were anchored onto graphitic carbon nitride (g-C₃N₄) to construct an Ohmic junction. The optimized 20 wt% Co₉S₈/g-C₃N₄ (20 % CoS/CN) photocatalyst achieved a hydrogen evolution rate of 3705.20 μmol·g^-1 within 4 h, representing a 12.54-fold enhancement over pristine g-C₃N₄. Experimental and density functional theory (DFT) calculations verified that the Ohmic junction effectively accelerated the separation and transfer of photogenerated charge carriers and significantly extended their lifetime. In addition, the Co₉S₈ cocatalyst improved the adsorption capacity for reactants, thereby substantially lowering the HER energy barrier and promoting the surface photocatalytic reactions. This work elucidates the fundamental mechanism of an Ohmic junction, and also offers new ideas for the design of Ohmic junction photocatalysts.