<p>Solar-driven photocatalytic water splitting for hydrogen production represents a highly promising clean energy technology; however, its practical deployment remains impeded by intrinsically narrow light absorption, severe recombination of photogenerated charge carriers, and sluggish surface reaction kinetics. In this work, we propose that nitrogen atoms within g-C₃N₄ quantum dots induce a local charge polarization effect, thereby facilitating the formation of a directed electron transfer channel at the heterointerface. This hypothesis is primarily supported by optoelectronic characterization results. Concurrently, quantum confinement effects and abundant surface unsaturated coordination sites endow the quantum dots with exceptional electron storage and transport capabilities, while simultaneously furnishing a high density of proton adsorption active centers. Under simulated solar irradiation, the C₃N₄ QDs-ZIS-1 composite achieves a hydrogen evolution rate of 4.2 mmol·g^− 1·h^− 1, approximately 1.91 times that of pristine ZnIn₂S₄, and exhibits excellent cycling stability. Mechanistic investigations reveal that the g-C₃N₄ quantum dots function as efficient electron acceptors and transfer mediators, where nitrogen-induced charge polarization markedly suppresses the recombination of photogenerated electron–hole pairs and accelerates surface proton reduction kinetics. This study elucidates the pivotal role of heteroatom-induced polarization effects in governing charge transfer dynamics at quantum dot/sulfide heterointerfaces, offering new atomistic-level design strategies for the development of non-noble-metal, highly efficient, and stable photocatalytic hydrogen evolution systems.</p> Graphical Abstract <p></p>