Lattice-embedded Ni single-atom catalyst on porous Al₂O₃ nanosheets derived from Ni-doped carbon dots for efficient propane dehydrogenation

The controlled synthesis of highly durable single-atom catalysts (SACs) for high-temperature applications remains a great challenge. Herein, we develop a facile strategy to construct Al2O3 lattice-embedded Ni SAC via thermal treatment of aluminum oxide encapsulated Ni-doped carbon dots (Ni-CDs@Al2O3). Detailed studies reveal that the Ni atoms are released from carbon matrix and simultaneously captured by cation defects formed in situ within a phase transformation of aluminum oxide. Al2O3 stabilized Ni atoms via Ni-O-4 coordination are well illustrated by combined characterizations. For propane dehydrogenation, reactivity measurements show that the center of Ni-O ion pairs effectively activates C3H8 and the higher rate of C3H6 formation on Ni SAs than Ni NPs, by a factor of 12, is the result of inhibition of C-C bond cleavage involving side reactions, as identified by density functional calculations. Beyond that, this lattice-embedded Ni SAC exhibits superior stability and recyclability in long-term operation with little coke accumulation.