Hollow fiber gas-diffusion electrodes with tailored crystal facets for tuning syngas production in electrochemical CO2 reduction
Guoliang Chen, Lei Ge, Yizhu Kuang, Hesamoddin Rabiee, Beibei Ma, Fatereh Dorosti, Ashok Kumar Nanjundan, Zhonghua Zhu, Hao Wang
Abstract
• Tailoring the crystal facet of electrocatalyst for syngas production. • HFGDEs provide sufficient CO 2 supply and improved triple-phase interfaces. • Syngas selectivity over 90 % and achieved a production rate of 1328.6 µmol/h∙cm 2 . • This strategy can be versatile by loading other nanostructured electrocatalysts. Electrochemical reduction of CO 2 (CO 2 RR) in aqueous electrolytes not only relies on advanced gas diffusion electrodes (GDEs) to improve CO 2 mass transportation but also efficient electrocatalysts to produce specific products. Herein, to produce syngas (CO and H 2 mixture), a facet-orientated zinc nanosheet catalyst was electrodeposited on the Cu hollow fiber GDE via a controllable facile surfactant-assisted method. The introduction of cationic surfactant cetyl trimethyl ammonium bromide (CTAB) could manipulate the nucleation and crystal growth of zinc ions around the GDE during the electrodeposition process, leading to controlled changes in the surface free energy and tuned zinc crystal growth orientation. Consequently, the ZncNS-HF with the largest ratio of Zn (1 0 1)/Zn (0 0 2), resulted in a high current density of 73.3 mA/cm 2 and a high syngas production rate of 1328.6 µmol/h∙cm 2 at applied potential −1.3 V (vs. RHE). This comes from the hierarchical structure of HFGDE, which provides sufficient CO 2 reaching the catalyst/electrolyte interface, and the well-connected zinc nanosheets contribute to a significant number of active sites for CO 2 RR. This is the first time to configure flow-through or gas-penetrated HFGDEs with zinc crystal facets controlled nanosheet catalysts for syngas production. This research demonstrates the high potential of nanoengineering catalysts for HFGDEs to achieve high production rates of syngas.