Identification of Metallic Nickel‐Hydroxyl Interfaces as Active Sites for Efficient Catalytic CO ₂ Hydrogenation

ABSTRACT

CO ₂ hydrogenation to methane is a promising strategy for sustainable fuel production and carbon emission control. Ni‐based catalysts are widely investigated for CO ₂ methanation, while the exact nature of active sites is still controversial. Here, we show that the metallic Ni in conjunction with hydroxyl groups plays a determining role in CO ₂ hydrogenation reaction. Keeping both the high proportion of Ni ⁰ and the high amount of OH groups achieves excellent catalytic activity. Conversely, a decrease in either the proportion of Ni ⁰ or the concentration of OH groups would result in a sharply decreased activity. We reveal that interfacial Ni ⁰ ‐OH sites are highly efficient for CO ₂ adsorption and activation, which follows the key step of CO ₂ hydrogenation to HCOO* and exhibits a lower barrier on the interfacial Ni ⁰ ‐OH sites than on the Ni ⁰ sites. These findings provide essential insights into the identification of active sites on Ni‐based catalysts for CO ₂ hydrogenation and are pivotal for the design of highly active catalysts.