Abstract
Acidic electrochemical CO(2) conversion is a promising alternative to overcome the low CO(2) utilization. However, over-reliance on highly concentrated K(+) to inhibit the hydrogen evolution reaction also causes (bi)carbonate precipitation to interfere with catalytic performance. In this work, under the screening and guidance of computational simulations, we present a carbon coated tip-like In(2)O(3) electrocatalyst for stable and efficient acidic CO(2) conversion to synthesize formic acid (HCOOH) with low K(+) concentration. The carbon layer protects the oxidized In species with higher intrinsic activity from reductive corrosion, and also peripherally formulates a tip-induced electric field to regulate the adverse H(+) attraction and desirable K(+) enrichment. In an acidic electrolyte at pH 0.94, only 0.1 M low K(+) is required to achieve a Faradaic efficiency (FE) of 98.9% at 300 mA cm(-2) for HCOOH and a long-time stability of over100 h. By up-scaling the electrode into a 25 cm(2) electrolyzer setup, a total current of 7 A is recorded to sustain a durable HCOOH production of 291.6 mmol L(-1) h(-1).