Fine-Tuning the Coordination Structure and Identifying Pt ₁ –O v –Ce as the Active Site for Selective Hydrogenations over Pt ₁ /CeO ₂ Single-Atom Catalysts

Single-atom catalysts (SACs) have shown exceptional promise in a variety of selective hydrogenations due to their uniform and isolated active sites, yet the intrinsic nature of the active sites and reaction mechanism remain elusive. Herein, by a rapid thermal treatment (RTT) method, we are able to finely tune the coordination structure of Pt 1 /CeO 2 SAC and establish a linear correlation between the Pt–O coordination number, electronic structure, and catalytic activity for furfural/3-nitrostyrene hydrogenations. Integrated quasi in situ spectroscopic characterizations and DFT calculations reveal the structural evolution of Pt 1 –O v –Ce active sites and the redox mechanism. RTT at 600 °C results in the formation of Pt 1 –O v –Ce, which allows for the preferential end-on adsorption of ─C═O/–NO 2 groups into O v and the charge transfer from the Pt 1 single atom to the reactant. On the other hand, hydrogen is dissociated on the Pt single atoms and then reacts with the adsorbed ─C═O/–NO 2 group to accomplish the selective hydrogenation, accompanied by the regeneration of O v . Moreover, the interfacial Pt 1 –O v –Ce is found to be 2.4–15.7-fold more active than Pt 1 –––O v (peripheral O v ). These findings highlight the dictating role of the coordination structure of SACs and elucidate the cooperative mechanism between Pt single atoms and interfacial oxygen vacancies, thus offering design principles for overcoming the activity-selectivity trade-off in other selective hydrogenations.