Document Type

Article

Publication Date

1-11-2019

DOI

10.1126/sciadv.aat5778

Publication Title

Science Advances

Volume

5

Issue

1

College/School

Case School of Engineering

Department/Center

Chemical & Biomolecular Engineering

Grant

W911NF-17-1-0119 and DE-SC0016529

Funder

U.S. Army Research Office; CWRU Faculty Investment Fund; U.S. Department of Energy, Office of Science, Basic Energy Sciences, Catalysis Science Program

Abstract

There is a growing need for scalable ammonia synthesis at ambient conditions that relies on renewable sources of energy and feedstocks to replace the Haber-Bosch process. Electrically driven approaches are an ideal strategy for the reduction of nitrogen to ammonia but, to date, have suffered from low selectivity associated with the catalyst. Here, we present a hybrid electrolytic system characterized by a gaseous plasma electrode that facilitates the study of ammonia formation in the absence of any material surface. We find record-high faradaic efficiency (up to 100%) for ammonia from nitrogen and water at atmospheric pressure and temperature with this system. Ammonia measurements under varying reaction conditions in combination with scavengers reveal that the unprecedented selectivity is achieved by solvated electrons produced at the plasma-water interface, which react favorably with protons to produce the key hydrogen radical intermediate. Our results demonstrate that limitations in selectivity can be circumvented by using catalyst-free solvated electron chemistry. In the absence of adsorption steps, the importance of controlling proton concentration and transport is also revealed.

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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