Insights into the shape effect of H2 self-selective Ni catalysts for efficient acetone hydrogenation

Highlights: • Branched Ni prepared by H₂ inducing dominantly exposed Ni(3 2 2) facet. • Ni-BN shows elegant activity for acetone hydrogenation to isopropanol. • DFT study reveals that step site in Ni(3 2 2) is favorable for the reaction. • Microkinetics study reaches quantitative shape-function relationship for activity. The shape-function relationship for designing catalysts is always a focus to study. This article describes the influence of Ni catalysts surface structure on acetone hydrogenation. We report H₂ as a morphology-directing agent to selectively synthesize branched Ni (Ni-BN), which exposes substantial stepped Ni(3 2 2) facet (~99%) that has elegant activity for acetone hydrogenation. In contrary, Ni nanoparticle (Ni-NP) prepared without H₂ mainly exposes flat Ni(1 1 1) and Ni(1 0 0) facets and these facets perform less activity for acetone hydrogenation to isopropanol. Subsequently, DFT studies of reaction mechanism on different facets reveal that the step site in Ni(3 2 2) facet displays lower activation barriers than that of Ni(1 1 1) and Ni(1 0 0) facets. With help of kinetic growth model and microkinetics study, quantitative shape-function relationship of Ni-BN for acetone hydrogenation to isopropanol can be further established. This work not only clarifies the catalytic activity of Ni on acetone hydrogenation but also provides a method accessing the intrinsic kinetics of the reaction.