Shape-tuned electrodeposition of bismuth-based nanosheets on flow-through hollow fiber gas diffusion electrode for high-efficiency CO2 reduction to formate

• Published in: Applied catalysis. B, Environmental Environmental, 2021-06, Vol.286, p.119945, Article 119945
• Main Authors: Rabiee, Hesamoddin, Ge, Lei, Zhang, Xueqin, Hu, Shihu, Li, Mengran, Smart, Simon, Zhu, Zhonghua, Yuan, Zhiguo
• Format: Article
• Language: English
• Subjects: 2D materials; Bicarbonates; Bismuth electrocatalyst; Bismuth oxides; Bismuth trioxide; Carbon dioxide; Catalysts; Charge transfer; Chemical reactions; Chemical reduction; CO2 electrochemical reduction reaction; Diffusion electrodes; Electrocatalysis; Electrochemistry; Electrode materials; Electrodeposition; Electrodes; Electrolytes; Electron transfer; Formate production; Gaseous diffusion; Hollow fiber gas diffusion electrodes; Interfaces; Mass transport; Nanosheets; Nanostructure; Oxidation; Oxidation resistance; Surface charge; Surface roughness; Wettability
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2021.119945

Pulse electrodeposition is a facile technique to control the shape of deposition. With syngergy of 2D Bismuth nanosheets from pulse electrodeposition and hollow fiber gas flow-through, advance electrodes for aqueous CO2 reduction are preapared. A thermal treatment to to maximize active sites and improves surface wettability of nanosheets resulted in highest formate current density in bicarbonate electrolyte was achieved. [Display omitted] •Uniform Bi nanosheets were electrodeposited on hollow fiber gas diffusion electrode.•Bi nanosheets showed significantly enhanced electrocatalytic active surface area.•Low-temperature thermal treatment boosted wettability/roughness of Bi nanosheets.•The highest current density of formate formation in bicarbonate media was obtained. Gas-phase CO2 electrochemical reduction reaction (CO2RR) requires advanced gas diffusion electrodes (GDEs) for efficient mass transport. Meantime, engineering catalyst nanostructure and tuning surface wettability are decisive to enhance three-phase interfaces formation. Herein, Bi-based nanosheets are uniformly grown on flow-through Cu hollow fiber GDE (HFGDE) to benefit from the unique shape of HFGDEs, and abundant active surface area of nanosheets. Pulse electrodeposition is used to replenish Bi3+ ions in the vicinity of HFGDEs for uniform growth of Bi nanosheets. Further, thermal oxidation of nanosheets not only maximized the active sites and improved surface wettability but also induced Bi/Bi2O3 junctions in nanosheets, enhancing formate production via switching the rate-limiting step from the initial electron transfer to hydrogenation. Consequently, a current density of 141 mA cm−2 at -1 V vs. RHE with formate faradaic efficiency of 85 % and over six times greater catalyst mass activity compared to bulk particle shaped Bi, were achieved, outperforming other reported Bi-based GDEs used for formate production in bicarbonate electrolytes. This comes from less charge-transfer resistance, higher surface roughness, and improved wettability of Bi nanosheets after oxidation. This work represents a facile strategy to engineer efficient HFGDEs as advanced electrode materials for similar electrochemical reactions with low aqueous solubility gas-phase feeds.