Supported metal catalysts are the backbone of heterogeneous catalysis, playing a crucial role in the modern chemical industry. Metal-support interactions (MSIs) are known important in determining the catalytic performance of supported metal catalysts. This is particularly true for single-atom catalysts (SACs) and pseudo-single-atom catalysts (pseudo-SACs), where all metal atoms are dispersed on, and interact directly with the support. Consequently, the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts. In this work, we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation. We fabricated CoFe 2 O 4 supported Pt pseudo-SACs and nanoparticle catalysts, followed by a straightforward water treatment process. It was found that the covalent strong metal-support interaction (CMSI) in pseudo-SACs can be weakened, leading to a significant activity improvement in methane combustion reaction. This finding aligns with our recent observation of CoFe 2 O 4 supported Pt SACs. By contrast, the MSI in Pt nanoparticle catalyst was barely affected by the water treatment, giving rise to almost unchanged catalytic performance. This work highlights the critical role of metal size in determining the MSI modulation, offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.
Yang Jingyi,Huang Yike,Qi Haifeng,Zeng Chaobin,Jiang Qike,Cui Yitao,Su Yang,Du Xiaorui,Pan Xiaoli,Liu Xiaoyan,Li Weizhen,Qiao Botao,Wang Aiqin,Zhang Tao
Metal-support interaction predominately determines the electronic structure of metal atoms in single-atom catalysts (SACs), largely affecting their catalytic performance. However, directly tuning the metal-support interaction in oxide supported SACs remains challenging. Here, we report a new strategy to subtly regulate the strong covalent metal-support interaction (CMSI) of Pt/CoFe 2 O 4 SACs by a simple water soaking treatment. Detailed studies reveal that the CMSI is weakened by the bonding of H + , generated from water dissociation, onto the interface of Pt-O-Fe, resulting in reduced charge transfer from metal to support and leading to an increase of C-H bond activation in CH 4 combustion by more than 50 folds. This strategy is general and can be extended to other CMSI-existed metal-supported catalysts, providing a powerful tool to modulating the catalytic performance of SACs.
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