2-Pyridinide as an Active Catalytic Intermediate for CO 2 Reduction on p-GaP Photoelectrodes: Lifetime and Selectivity

Shenzhen Xu, Emily A. Carter

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22 Scopus citations


The active intermediate responsible for pyridine (Py)-catalyzed reduction of CO 2 on a p-GaP photoelectrode is currently under debate. Exploration of the proposed intermediates' available pathways for further reaction may yield a deeper understanding of the CO 2 reduction mechanism that will be essential to designing better cocatalysts in such photoelectrochemical systems. Adsorbed 2-pyridinide (2-PyH - ∗) was recently proposed by Carter and co-workers to be an intermediate that facilitates hydride transfer (HT) to CO 2 to produce formate. However, the lifetime of 2-PyH - ∗, most likely controlled by the rate of 2-PyH - ∗ protonation to form adsorbed dihydropyridine (DHP∗), is still in question. In this work, we provide evidence for the transient existence of 2-PyH - ∗ on a p-GaP surface by comparing the activation energy for HT to CO 2 to those predicted for 2-PyH - ∗ being protonated to form either DHP∗ or Py∗ + H 2 via a hydrogen evolution reaction (HER). We predict that 2-PyH - ∗ situated next to an adjacent surface hydroxide (OH - ∗) will be the most effective intermediate leading to CO 2 reduction on p-GaP. Predicted high barriers of HER (via either 2-PyH - ∗ or H - ∗) also explain the high selectivity toward CO 2 reduction observed in experiments.

Original languageEnglish (US)
Pages (from-to)8732-8738
Number of pages7
JournalJournal of the American Chemical Society
Issue number28
StatePublished - Jul 18 2018

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


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