Ethylene Electrosynthesis from Acetylene at Ampere-Level Current Density via Promoting Interparticle Mass Transport

The electrocatalytic acetylene semi-hydrogenation (EASH) driven by renewable energy offers an important non-petroleum route for ethylene production, yet suffers from insufficient reaction rate, ethylene selectivity, and energy efficiency. While tailoring catalytically active structures is effective for improving the EASH performance, the effects of mass transport at the mesoscale are poorly understood. Here, we show quantitatively the crucial role of interparticle mass transport within the catalyst layer of a gas diffusion electrode. Increasing the average interparticle distance of Cu cubes remarkably improves the EASH performance. The Cu cube electrode with a large average interparticle distance of 265 nm exhibits an ethylene Faradaic efficiency of 97.4% at a current density of 1.0 A cm^-2 and a maximum ethylene partial current density as high as 1.5 A cm^-2 in an alkaline membrane electrode assembly electrolyzer. Electrochemical impedance spectroscopy, operando Raman spectroscopy, and finite element simulation results reveal that increasing the interparticle distance of Cu cubes can effectively promote interparticle mass transport, which accelerates acetylene adsorption and ethylene desorption, thus resulting in the excellent ethylene electrosynthesis performance. This work underscores the importance of tuning mesoscopic mass transport for improving electrocatalytic performance.