Nonsteady-State Oxidative Modulation of Pt Coordination on CeO2 to Balance the Activity–Selectivity Trade-Off in the Selective Hydrogenation of Nitroarenes

Describing and disentangling the catalytic activity-selectivity trade-off remains a fundamental challenge in heterogeneous catalysis, particularly in reactions involving multifunctional groups. Herein, we report an effective strategy to balance this trade-off in the selective hydrogenation of nitroarenes by employing surface hydrogen-oxygen pulse titration under an oxidative atmosphere to initiate nonsteady-state oxidative modulation of Pt/CeO2 coordination. Thermochemical analysis and DFT calculations reveal that the pulsed treatment induces a transient exothermic process, driving the oxidation and structural fragmentation of Pt nanoparticles and gradually leading to the formation of isolated Pt1 single atoms. Atomic-resolution electron microscopy and quasi in situ X-ray spectroscopy further demonstrate that, unlike conventional thermodynamic treatments, this transiently induced evolution results in tunable coordination environments (from nanoparticles to single atoms) of central Pt atoms. In this structural transformation, the constructed Pt1-O2 single-atom sites on the CeO2 surface, with an average Pt oxidation state of ∼+0.9, not only enable preferential adsorption and activation of the nitro group while suppressing undesired hydrogenation of other reducible functionalities (e.g., C═C group) but also retain high H2 activation capability. As a result, the traditional activity-selectivity seesaw is shifted toward an optimized balance, affording outstanding performance in the selective hydrogenation of 4-nitrostyrene (2143 h-1 turnover frequency, 96% selectivity), as well as excellent substrate adaptability (10 types of substrates). This study offers new insights into coordination environment engineering via transient treatments and provides a general approach for the rational design of high-performance catalysts in complex hydrogenation reactions.