<p>Nickel-based sulfides have attracted much more interest in field of photocatalytic H₂ evolution due to their potential as alternatives to noble metal-based catalysts. In this study, Ni₃S₄ co-catalyst was synthesized by an alkaline hydrothermal method with precise control over the optimal synthesis temperature. Subsequently, it was deposited onto the surface of g-C₃N₄ nanosheets using a solvent evaporation strategy to obtain 0D/2D Ni₃S₄/g-C₃N₄ composite material. The investigation reveals the optimal H₂ evolution rate of 20% (mass fraction) Ni₃S₄/g-C₃N₄ reaches 17566.25 μmol·g^-1·h^-1 under a 300 W Xe lamp and in a 20% (volume fraction) triethanolamine (TEOA) solution, representing a 158.5-fold enhancement compared to pure g-C₃N₄ (110.13 μmol·g.1·h.1). It has been demonstrated that the Ni₃S₄ co-catalyst facilitates transfer of photogenerated electrons, thereby enhancing electrical conductivity and reducing charge transfer resistance in the Ni₃S₄/g-C₃N₄ compared to pure g-C₃N₄. Furthermore, the contact interface between Ni₃S₄ and g-C₃N₄ conforms to a Schottky junction, further enhancing the charge separation efficiency. Additionally, Ni₃S₄ exhibits the ability to adsorb OH. ions from water, increasing the effective reaction active sites, reducing the H₂-releasing overpotential, and improving the H₂ evolution kinetics of the system.</p>