Molecular Coatings Improve the Selectivity and Durability of CO2 Reduction Chalcogenide Photocathodes

Yungchieh Lai, Nicholas Watkins, Christopher Muzzillo, Matthias Richter, Kevin Kan, Lan Zhou, Joel Haber, Andriy Zakutayev, Jonas Peters, Theodor Agapie, John Gregoire

Research output: Contribution to journalArticlepeer-review

8 Scopus Citations


The quest for solar-driven conversion of carbon dioxide to chemicals and fuels hinges upon the identification of an efficient, durable, and selective photocathode. Chalcogenide p-type semiconductors exemplified by chalcopyrite Cu(In,Ga)Se2 (CIGS) have been effectively deployed as photocathodes. However, selectivity toward CO2 reduction and durability of the commonly used CdS adlayer remain primary challenges. Here, we demonstrate that for the wide band gap CuGa3Se5 chalcopyrite absorber these challenges are well addressed by an organic coating generated in situ from an N,N′-(1,4-phenylene)bispyridinium ditriflate salt in the electrolyte. The molecular additive provides a 30-fold increase in selectivity toward CO2R products compared to the unmodified system and lowers Cd corrosion at least 10-fold. This dual functionality highlights the promise of hybrid solid-state-molecular photocathodes for enabling durable and efficient solar fuel systems.

Original languageAmerican English
Pages (from-to)1195-1201
Number of pages7
JournalACS Energy Letters
Issue number3
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 American Chemical Society

NREL Publication Number

  • NREL/JA-5K00-81932


  • CO2
  • photocathode
  • reduction


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