| Institution: | 1. Hunan Joint International Research Center for Carbon Dioxide Resource Utilization, School of Physics, Central South University, Changsha, 410083, Hunan P. R. China
These authors contributed equally to this work.;2. Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität München, 80539 München, Germany;3. Hunan Joint International Research Center for Carbon Dioxide Resource Utilization, School of Physics, Central South University, Changsha, 410083, Hunan P. R. China;4. Chemistry Department, Faculty of Science, Fayoum University, Fayoum, 63514 Egypt;5. Central Metallurgical Research and Development Institute, CMRDI P.O. Box: 87, Helwan, 11421, Cairo Egypt |
| Abstract: | Electrocatalytic CO2 reduction reaction (CO2RR) to multi-carbon products (C2+) in acidic electrolyte is one of the most advanced routes for tackling our current climate and energy crisis. However, the competing hydrogen evolution reaction (HER) and the poor selectivity towards the valuable C2+ products are the major obstacles for the upscaling of these technologies. High local potassium ions (K+) concentration at the cathode's surface can inhibit proton-diffusion and accelerate the desirable carbon-carbon (C−C) coupling process. However, the solubility limit of potassium salts in bulk solution constrains the maximum achievable K+ concentration at the reaction sites and thus the overall acidic CO2RR performance of most electrocatalysts. In this work, we demonstrate that Cu nanoneedles induce ultrahigh local K+ concentrations (4.22 M) – thus breaking the K+ solubility limit (3.5 M) – which enables a highly efficient CO2RR in 3 M KCl at pH=1. As a result, a Faradaic efficiency of 90.69±2.15 % for C2+ (FEC2+) can be achieved at 1400 mA.cm−2, simultaneous with a single pass carbon efficiency (SPCE) of 25.49±0.82 % at a CO2 flow rate of 7 sccm. |
