Single-Atom Catalysts for Hydrogen Activation.

Selective hydrogenation is one of the most important reactions in fine chemical industry, and the activation of H is the key step for hydrogenation. Catalysts play a critical role in selective hydrogenation, and some single-atom catalysts (SACs) are highly capable of activating H in selective hydrogenation by virtue of the maximized atom utilization and the highly uniform active sites. Therefore, more research efforts are needed for the rational design of SACs with superior H -activating capabilities. Herein, the research progress on H activation in typical hydrogenation systems (such as alkyne hydrogenation, hydroformylation, hydrodechlorination, hydrodeoxygenation, nitroaromatics hydrogenation, and polycyclic aromatics hydrogenation) is reviewed, the mechanisms of SACs for H activation are summarized, and the structural regulation strategies for SACs are proposed to promote H activation and provide schemes for the design of high-selectivity hydrogenation catalysts from the atomic scale. At the end of this review, an outlook on the opportunities and challenges for SACs to be developed for selective hydrogenation is presented.