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Photoelectrochemical Nitrogen Reduction to Ammonia on Cupric and Cuprous Oxide Photocathodes
journal contribution
posted on 2020-05-18, 14:41 authored by Youn Jeong Jang, Ann E. Lindberg, Margaret A. Lumley, Kyoung-Shin ChoiPhotoelectrochemical
N2 reduction enables the production
of NH3 under ambient conditions using water as the hydrogen
source. Furthermore, by utilizing solar energy, photoelectrochemical
N2 reduction can significantly reduce the amount of energy
required for N2 reduction. In this study, photoelectrochemical
N2 reduction was investigated using CuO and Cu2O photocathodes that are known to be poorly catalytic for water reduction,
the major reaction competing with N2 reduction. When tested
under simulated solar illumination with isotopically labeled 15N2 in a 0.1 M KOH solution, the CuO and Cu2O photocathodes produced 15NH3 with
Faradaic efficiencies of 17% and 20% at 0.6 and 0.4 V vs the reversible
hydrogen electrode, respectively. These potentials are significantly
more positive than the thermodynamic reduction potential of N2, which demonstrates how the use of photoexcited electrons
in the CuO and Cu2O photocathodes can reduce the amount
of energy required for NH3 production. The use of photoexcited
electrons in these photocathodes for N2 reduction, water
reduction, and photocorrosion was carefully examined.