Microenvironment Tuning through Bi Morphology for Efficient Bicarbonate Electroreduction.

Wang, Miao; Hu, Bihao; Zheng, Yifan; Wang, Lei · Nano Lett · 2026

basic_science · Level V

Where this comes from

Abstract

Bicarbonate electroreduction in cation exchange membrane-based assemblies provides a complementary route for CO<sub>2</sub> conversion but is limited by coupled CO<sub>2</sub> concentration and interfacial pH. Here, we design a bismuth nanoflower (Bi-NF) catalyst with interconnected channels that enhance mass transfer, regulate local pH, and facilitate CO<sub>2</sub> diffusion. Electrochemical open-circuit potential measurements quantify interfacial pH, revealing that elevated pH promotes <i>in situ</i> CO<sub>2</sub> generation, boosting selectivity and lowering cell voltage. Incorporating a hydrophilic filter membrane further extends OH<sup>-</sup> and CO<sub>2</sub> transport pathways. The optimized Bi-NF electrode achieves nearly 100% Faradaic efficiency for formate at 50 mA cm<sup>-2</sup> and a practical partial current density of 240 mA cm<sup>-2</sup> at 3.5 V. These results demonstrate that combining morphology engineering with controlled mass transport is an effective strategy to enhance performance and elucidate the mechanisms of bicarbonate electrolysis.