Electronic metal–support interaction in Pd/CoNi-hydroxides with enhanced CO adsorption for boosting CO2 methanation†

Abstract

CO₂ conversion to value-added chemical products is of significance for carbon cycling. Pd-based catalysts show great potential in the CO₂ methanation reaction by virtue of the synergistic effect between the Pd and support, but the limited interaction sites on the support often restrict further optimization of the Pd electronic state. Herein, CoNi-hydroxide nanosheets with abundant defects were synthesized and provided numerous interaction sites for loading Pd nanoparticles, leading to enriched electron density of Pd sites with strong CO adsorption intensity. TEM and XRD revealed the solid solution structure of CoNi-hydroxide nanosheets with lattice distortions, which provided numerous defects for interaction sites. The close interface served as an electron transfer pathway from Co to Pd sites, as confirmed by XAS analysis. Meanwhile, the electron-rich Pd sites exhibited stronger CO intermediate adsorption strength. As a result, a good CH₄ production rate of 2255 μmol g_cat⁻¹ h⁻¹ at 573 K was obtained over CoNi-hydroxides decorated with Pd, which was 64 times greater than that of Pd/AC and twice that of the pristine CoNi-hydroxide catalyst.