A Framework for Understanding Efficient Diurnal CO2 Reduction Using Si and GaAs Photocathodes

Kyra Yap, Sang-Won Lee, Myles Steiner, Jaime Aviles Acosta, Dongkyun Kang, Dongwhan Kim, Emily Warren, Adam Nielander, Thomas Jaramillo

Research output: Contribution to journalArticlepeer-review

5 Scopus Citations


Integrated solar fuels and photoelectrochemical (PEC) CO2 reduction (CO2R) are promising pathways toward producing value-added chemicals from CO2. However, improvements are needed in activity and selectivity as well as in fundamental understanding of device behavior to engender wide deployment. We report two single-junction, integrated photocathodes for PEC CO2R based on TOPCon Si and GaAs substrates, which achieve −10 mA cm−2 at −0.33 V vs. RHE with 41% selectivity to C2+ products and at −0.03 V vs. RHE with 27% selectivity to C2+ products, respectively. We investigated the viability of a light-mediated strategy to direct selectivity in buried-junction PEC devices and confirmed that these devices could be optimized independently and described by the physics-based models of the individual components. Finally, we designed a framework to assess operational modes for PEC CO2R devices and demonstrated this framework under continuous galvanostatic control and variable illumination conditions.

Original languageAmerican English
Article number100641
Number of pages16
JournalChem Catalysis
Issue number6
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 Elsevier Inc.

NREL Publication Number

  • NREL/JA-5900-84699


  • catalysis
  • CO reduction
  • diurnal
  • electrocatalysis
  • electrochemistry
  • GaAs
  • light
  • photoelectrochemistry
  • SDG7: Affordable and clean energy
  • solar
  • solar fuels


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