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This content will become publicly available on June 22, 2018

Title: Understanding Selectivity for the Electrochemical Reduction of Carbon Dioxide to Formic Acid and Carbon Monoxide on Metal Electrodes

Increases in energy demand and in chemical production, together with the rise in CO 2 levels in the atmosphere, motivate the development of renewable energy sources. Electrochemical CO 2 reduction to fuels and chemicals is an appealing alternative to traditional pathways to fuels and chemicals due to its intrinsic ability to couple to solar and wind energy sources. Formate (HCOO ) is a key chemical for many industries; however, greater understanding is needed regarding the mechanism and key intermediates for HCOO production. This work reports a joint experimental and theoretical investigation of the electrochemical reduction of CO 2 to HCOO on polycrystalline Sn surfaces, which have been identified as promising catalysts for selectively producing HCOO . Our results show that Sn electrodes produce HCOO , carbon monoxide (CO), and hydrogen (H 2) across a range of potentials and that HCOO production becomes favored at potentials more negative than –0.8 V vs RHE, reaching a maximum Faradaic efficiency of 70% at –0.9 V vs RHE. Scaling relations for Sn and other transition metals are examined using experimental current densities and density functional theory (DFT) binding energies. While *COOH was determined to be the key intermediate for CO productionmore » on metal surfaces, we suggest that it is unlikely to be the primary intermediate for HCOO production. Instead, *OCHO is suggested to be the key intermediate for the CO 2RR to HCOO transformation, and Sn’s optimal *OCHO binding energy supports its high selectivity for HCOO . Lastly, these results suggest that oxygen-bound intermediates are critical to understand the mechanism of CO 2 reduction to HCOO on metal surfaces.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [2] ;  [2] ; ORCiD logo [1] ;  [1] ; ORCiD logo [1]
  1. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Stanford Univ., Stanford, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; 1066515
Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 7; Journal Issue: 7; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; carbon monoxide; CO2 reduction; electrocatalysis; formate; Sn; tin
OSTI Identifier:
1390311