Renewable energy-based electrocatalytic hydrogenation of acetylene to ethylene (E-HAE) under mild conditions is an attractive substitution to the conventional energy-intensive industrial process, but is challenging due to its low Faradaic efficiency caused by competitive hydrogen evolution reaction. Herein, we report a highly efficient and selective E-HAE process at room temperature and ambient pressure over the Cu catalyst. A high Faradaic efficiency of 83.2% for ethylene with a current density of 29 mA cm−2 is reached at −0.6 V vs. the reversible hydrogen electrode. In-situ spectroscopic characterizations combined with first-principles calculations reveal that electron transfer from the Cu surface to adsorbed acetylene induces preferential adsorption and hydrogenation of the acetylene over hydrogen formation, thus enabling a highly selective E-HAE process through the electron-coupled proton transfer mechanism. This work presents a feasible route for high-efficiency ethylene production from E-HAE.

The molecular dynamic (MD) simulation and quantum chemical calculations for the adsorption of [2-(2-Henicos-10-enyl-4,5-dihydro-imidazol-1-yl)-ethyl]-methylamine (HDM) and 2-(2-Henicos-10-enyl-4,5-dihydro-imidazol-1-yl)-ethanol (HDE) on iron surface was studied using Materials Studio software. Molecular dynamic simulation results indicate that the imidazoline derivative molecules uses the imidazoline ring to effectively adsorb on the surface of iron, with the alkyl hydrophobic tail forming an n shape (canopy like covering) at geometry optimization and at 353 K. The n shape canopy like covering to a large extent may prevent water from coming in close contact with the Fe surface. The quantum chemical calculation based on the natural atomic charge, the frontier molecular orbital and the Fukui indices values and plots shows the active sites of the molecules to be mainly the N=C-N region in the imidazoline ring, others include the nitrogen and oxygen heteroatoms in the pendant part and the double bonded carbon atoms in the hydrophobic tail of the imidazoline derivative molecules. The quantum chemical calculations also reveal that the amine group in HDM and the hydroxyl group in HDE which is attached to the imidazoline ring do not result in a significant increase in the HOMO nor the LUMO density which can aid adsorption.HDM has a lower energy gap of 4.434 eV and 3.824 eV, a higher E HOMO of -4.273 eV and -4.152 eV and a higher global softness of 0.45 and 0.52 compared to HDE which have an energy gap of 4.476 eV and 4.084 eV, a E HOMO of -4.349 eV and -4.607 eV and a global softness of 0.45 and 0.49 at geometry optimization and at 353 K. The adsorption ability of the molecule is given as at geometry optimization HDM > HDE and at 353 K HDM > HDE. Theoretically HDM is a better inhibitor than HDE. The adsorption ability of the molecule is in line with the binding energy at the temperature studied.