Hyo Cheol Lee, Su‐Il In
The transition to sustainable energy requires efficient technologies for solar‐driven hydrogen production. Quantum dots (QDs), with size‐tunable bandgaps and favorable interfacial properties, significantly enhance photoelectrochemical (PEC) water splitting by enabling broad‐spectrum light harvesting, optimized band alignment, and improved charge separation. However, QD design strategies for PEC systems remain less developed compared to those for light‐emitting diodes and solar cells, constrained by incomplete understanding of interfacial photophysics, limited exploration of low‐dimensional nanocrystals (1D/2D), and the absence of AI‐assisted optimization. This review provides a comprehensive overview of material design strategies for QDs in PEC hydrogen production, encompassing fundamental principles, established approaches, and recent advances in both heavy‐metal‐based and nontoxic systems. Particular attention is given to emerging paradigms such as dimensional control and AI‐driven optimization, which enable predictive modeling, accelerated synthesis, and performance tuning beyond conventional trial‐and‐error methods. Finally, we address critical challenges—including stability, toxicity, and scalability—and outline future directions for achieving efficient, sustainable QD‐based PEC systems suitable for practical and economically viable commercialization.