The Role of Intrinsic Defects in Photocatalysis of Quantum Dots: An Ideal Photocatalyst Is Based on an Ideal Light Emitter?

Quantum dots (QDs) have gained significant attention due to their unique photophysical and photochemical properties, demonstrating promising potential for diverse photocatalytic transformations. However, the principle for QD selection for photocatalysis remains debated. A critical question emerges against the background that near-unity photoluminescence quantum yield (PLQY) QDs become commonly available: Should QD photocatalysts prioritize high-PLQY QDs or low-PLQY ones to maximize catalytic performance? To address this question, CdSe-based QDs are selected as a model system, and the role of intrinsic defects of QDs is discussed, which serve as the direct linkage between PLQY and photocatalytic performance of QDs. Defect states are known to quench PLQY, while their effects on photocatalysis-either promoting or suppressing-are both widely reported. Representative studies on PLQY-related photocatalysis are then reviewed. This debate is finally resolved through mechanistic insights into defects, and it is proposed that ideal photocatalysts should be based on ideal light-emitters. For specific photocatalytic applications, initial PLQY should be paid attention and surface-engineering strategies should be applied to pristine defects-eliminated QDs.