Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry

Thomas Burdyny, Percival J. Graham, Yuanjie Pang, Cao Thang Dinh, Min Liu, Edward H. Sargent, David Sinton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

130 Scopus citations

Abstract

Nanostructured CO2 reduction catalysts now achieve near-unity reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent surface reaction kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm-2. We show here that - in addition to influencing reaction rates and local reactant concentration - the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 μm, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode's surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm-2 production. We further extend this model to study the influence of mass transport on achieving simultaneously high selectivity and current density of C2 reduction products, identifying precise control of the local fluid environment as a crucial step necessary for producing C2 over C1 products.

Original languageEnglish (US)
Pages (from-to)4031-4040
Number of pages10
JournalACS Sustainable Chemistry and Engineering
Volume5
Issue number5
DOIs
StatePublished - May 1 2017

Keywords

  • CO reduction
  • Electrocatalysis
  • Gas-evolution
  • Limiting current
  • Mass transport
  • Nanomorphology

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Renewable Energy, Sustainability and the Environment

Fingerprint

Dive into the research topics of 'Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry'. Together they form a unique fingerprint.

Cite this