Abstract
In situ tuning of the electronic structure of active sites is a long-standing challenge. Herein, we propose a strategy by controlling the hydrogen spillover distance to in situ tune the electronic structure. The strategy is demonstrated to be feasible with the assistance of CoO(x)/Al(2)O(3)/Pt catalysts prepared by atomic layer deposition in which CoO(x) and Pt nanoparticles are separated by hollow Al(2)O(3) nanotubes. The strength of hydrogen spillover from Pt to CoO(x) can be precisely tailored by varying the Al(2)O(3) thickness. Using CoO(x)/Al(2)O(3) catalyzed styrene epoxidation as an example, the CoO(x)/Al(2)O(3)/Pt with 7 nm Al(2)O(3) layer exhibits greatly enhanced selectivity (from 74.3% to 94.8%) when H(2) is added. The enhanced selectivity is attributed to the introduction of controllable hydrogen spillover, resulting in the reduction of CoO(x) during the reaction. Our method is also effective for the epoxidation of styrene derivatives. We anticipate this method is a general strategy for other reactions.