To mitigate this challenge, we used a ″surface phase oxide″ in the form of MgAl hydrotalcite nanosheets (<2 nm thick) as an interlayer SIS to mediate the interaction between nickel nanoparticles and an underlying WIS (i.e. ZrO2 or SiO2). We show that this hierarchical configuration, in which the Ni is supported only on the hydrotalcite SIS nanosheets, the obtained reaction performance, for an unoptimized reaction conditions, enhanced the conversion by up to 2-fold, as compared to Ni supported on ZrO2, and by up to 15-fold as compared to Ni on bulk Mg-Al hydrotalcite. Moreover, selectivity of the hierarchical catalyst was similar to that of the Ni on ZrO2, despite the fact that the Ni phase had virtually no physical interaction with the underlying ZrO2. We found that the interaction of the Ni nanoparticles with the hydrotalcite surface phase oxide maintained a stable 2 nm Ni catalyst for a total of 250 h on stream. H2-TPR analysis showed that the presence of the SIS surface phase oxide increased the Ni reduction temperature above that of the underlying ZrO2 but kept it below that of Ni supported on bulk hydrotalcite. To gain better understanding into the mechanism of enhanced catalytic performance we used a combination of PXRD, SAXS, Cryo-TEM, H2-TPR, STEM-EDS, and XPS in conjunction with the results for the catalytic performance and kinetic analysis. The combined results show that the amplified catalytic performance is strongly correlated with the modification of the metal-support interaction (MSI) by the MgAl hydrotalcite nanosheets interlayer. The changes in MSI interactions is postulated to arise either due to the ability of the Ni sites to electronically communicate with the underlying ZrO2 or due to the effect of the new interface between the hydrotalcite nanosheets and the underlying ZrO2. Molecular level studies into these effects are being conducted using atomic friction force microscopy, in situ-spectroscopy analysis and temperature programmed adsorption measurements.
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