Preparing catalysts with well-defined structures featuring one or few active metal atoms is not only important for the study of catalytic mechanisms, but also critical for full utilization of catalytic active metals, especially in the case of water oxidation where the rare Ir element is usually required for efficient catalysis. While single atom catalysts (SACs) with single catalytic active atom have been extensively studied recently, catalysts with two catalytic active atoms are rarely reported in literature. We anchored a recently developed molecular Ir catalyst, which has been suggested to be a mono-μ-oxo bridge dimer, on metal oxide substrates to prepare Ir dual atom catalysts (DAC). Through metal-substrate interatomic matching, we were able to prepare Ir dual atom catalysts in both end-on and side-on binding mode. The interactions between Ir DACs and substrates were studied with density functional theory (DFT), and in situ CO diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy, and High-angle Annular Dark-field Scanning Transmission Electron Microscopy (HAADF-STEM). Based on our developed structural models, we investigated the catalytic mechanisms of water oxidation computationally. Our results suggest that Ir DAC is more active than Ir SAC for water oxidation and the catalytic mechanisms can be affected by how catalysts bind on substrates.

Modulating binding modes of Ir dual atom catalysts by metal-substrate interatomic matching and its application to solar water splitting

256th National Meeting (2018)

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