Ultrathin two-dimensional mesoporous holmium oxide nanosheet-stabilized copper nanoparticles for stable and efficient electrocatalytic semi-hydrogenation of acetylene†

Abstract

The removal of acetylene (C₂H₂) impurities from ethylene (C₂H₄) is a critical step in the production of high-purity C₂H₄. Due to its low reaction temperature, low energy consumption and high selectivity for C₂H₄, the electrocatalytic semi-hydrogenation of C₂H₂ is an ideal method for removing C₂H₂. Herein, ultrathin two-dimensional (2D) mesoporous holmium oxide nanosheet-stabilized copper nanoparticles (Cu/Ho₂O₃) for stable and efficient electrocatalytic semi-hydrogenation of C₂H₂ were prepared through a simple and one-step high-temperature calcination-reduction method. The ultra-thin two-dimensional mesoporous structure of holmium oxide creates abundant coordination defects, improving the faradaic efficiency and durability of copper nanoparticles for catalyzing the semi-hydrogenation of C₂H₂. The as-prepared Cu/Ho₂O₃ achieved a C₂H₄ selectivity of 99.6% and a faradaic efficiency of 98.1% because the presence of oxygen vacancies is conducive to forming electron-rich Cu nanoparticles, thereby promoting the adsorption of electrophilic C₂H₂ and the desorption of nucleophilic C₂H₄. Meanwhile, the holmium oxide nanosheet with unsaturated coordination sites can stabilize the Cu nanoparticles, and the faradaic efficiency and current density remain stable for more than 600 minutes. This work offers a promising design strategy for a stable and efficient electrocatalyst for the semi-hydrogenation of C₂H₂ to C₂H₄.