Acidic CO <sub>2</sub> Electrolysis With Near‐Ideal Selectivity and Carbon Efficiency Enabled by Overcoming Its Inherent Trade‐Off
Li‐Ping Chi, Yu‐Cai Zhang, Zhuang‐Zhuang Niu, Xiao‐Long Zhang, Ye‐Cheng Li, Tian‐Yun Zhang, Shu‐Ping Sun, Pu‐Gan Lu, Kai‐Bin Tang, Min‐Rui Gao
Abstract
Abstract Carbon dioxide electroreduction (CO 2 R) in acid tends to be a promising route to avoid CO 2 loss in alkaline and neutral electrolytes; however, high alkali cation concentrations (typically ≥3 M) are required to activate CO 2 and suppress water electroreduction, causing carbonate formation and thus unsatisfied single‐pass carbon efficiency (SPCE). Based on theoretical and experimental analyses, we show that an inherent trade‐off exists: increasing cation concentrations improves Faradaic efficiency (FE) toward CO 2 R products but comes at the expense of reduced SPCE. We demonstrate a polyimide‐modification strategy to overcome this trade‐off by taking advantage of the amino groups that can effectively capture protons, creating a local alkaline microenvironment surrounding the electrode surface. In a proof‐of‐concept experiment, SnO 2 nanoparticles were modified with polyimide and acted as a CO 2 R catalyst, which achieved, simultaneously, near‐ideal SPCE of 95.7% and FE of 96% (toward HCOOH) at pH 1.36 with dilute potassium ions down to even 0.1 M. We expect that these findings will accelerate the development of carbon‐ and electron‐efficient acidic CO 2 electrolysis.