High Current Density Electroreduction of CO2 into Formate with Tin Oxide Nanospheres: Article No. 8420

Thuy-Duong Nguyen-Phan, Leiming Hu, Bret Howard, Wenqian Xu, Eli Stavitski, Denis Leshchev, August Rothenberger, Kenneth Neyerlin, Douglas Kauffman

Research output: Contribution to journalArticlepeer-review

13 Scopus Citations

Abstract

In this study, we demonstrate three-dimensional (3D) hollow nanosphere electrocatalysts for CO2 conversion into formate with excellent H-Cell performance and industrially-relevant current density in a 25 cm2 membrane electrode assembly electrolyzer device. Varying calcination temperature maximized formate production via optimizing the crystallinity and particle size of the constituent SnO2 nanoparticles. The best performing SnO2 nanosphere catalysts contained ~7.5 nm nanocrystals and produced 71-81% formate Faradaic efficiency (FE) between -0.9 V and -1.3 V vs. the reversible hydrogen electrode (RHE) at a maximum formate partial current density of 73 +/- 2 mA cmgeo-2 at -1.3 V vs. RHE. The higher performance of nanosphere catalysts over SnO2 nanoparticles and commercially-available catalyst could be ascribed to their initial structure providing higher electrochemical surface area and preventing extensive nanocrystal growth during CO2 reduction. Our results are among the highest performance reported for SnO2 electrocatalysts in aqueous H-cells. We observed an average 68 +/- 8% FE over 35 h of operation with multiple on/off cycles. In situ Raman and time-dependent X-ray diffraction measurements identified metallic Sn as electrocatalytic active sites during long-term operation. Further evaluation in a 25 cm2 electrolyzer cell demonstrated impressive performance with a sustained current density of 500 mA cmgeo-2 and an average 75 +/- 6% formate FE over 24 h of operation. Our results provide additional design concepts for boosting the performance of formate-producing catalysts.
Original languageAmerican English
Number of pages10
JournalScientific Reports
Volume12
DOIs
StatePublished - 2022

NREL Publication Number

  • NREL/JA-5900-80672

Keywords

  • CO2 reduction
  • formate
  • formic acid
  • gas diffusion electrode
  • membrane electrode assembly

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