Promoted hydrogen activation and spillover over Pt/Co₃O₄ by facet engineering of Co₃O₄ for enhanced catalytic...

The exposed facets of supported metal catalysts play a crucial role in catalytic hydrogenation performance. However, the internal relationship between the support crystal facet and catalytic performance needs to be further explored. Herein, a series of well-defined Pt/Co₃O₄-x catalysts are fabricated with similar Pt nanoparticle sizes, identical metal loadings, and tailored Co₃O₄ crystal facets (x = o, t, c; where "o", "t", and "c" denote Co₃O₄ exposing predominantly (111), mixed (111)/(100), and (100) facets, respectively). The electronic structure of Pt nanoparticles and the hydrogen spillover capability of Pt/Co₃O₄ are modulated by exposing different crystal facets of Co₃O₄. For the 4-nitrophenol (4-NP) hydrogenation reaction with H₂ as the hydrogen source, the Pt/Co₃O₄-o catalyst with more Pt⁰ species and stronger hydrogen spillover capability exhibits the best hydrogenation activity with a turnover frequency (TOF) of 164.2 h^-1. Mechanistic studies indicate that, compared with Pt/Co₃O₄-c, the Pt/Co₃O₄-o exhibits weaker adsorption and activation of the nitro group, while its ability to activate H₂ is stronger. The enhanced catalytic activity of Pt/Co₃O₄-o is attributed to promoted hydrogen activation and spillover. This work highlights support crystal facet engineering for regulating the electronic structure and hydrogen spillover effect, which provides in-depth insight into catalyst design and hydrogenation mechanism.