A physical catalyst for the electrolysis of nitrogen to ammonia

Yang Song, Daniel Johnson, Rui Peng, Dale K. Hensley, Peter V. Bonnesen, Liangbo Liang, Jingsong Huang, Fengchang Yang, Fei Zhang, Rui Qiao, Arthur P. Baddorf, Timothy J. Tschaplinski, Nancy L. Engle, Marta C. Hatzell, Zili Wu, David A. Cullen, Harry M. Meyer, Bobby G. Sumpter, Adam J. Rondinone

Research output: Contribution to journalArticlepeer-review

292 Scopus citations

Abstract

Ammonia synthesis consumes 3 to 5% of the world’s natural gas, making it a significant contributor to greenhouse gas emissions. Strategies for synthesizing ammonia that are not dependent on the energy-intensive and methane-based Haber-Bosch process are critically important for reducing global energy consumption and minimizing climate change. Motivated by a need to investigate novel nitrogen fixation mechanisms, we herein describe a highly textured physical catalyst, composed of N-doped carbon nanospikes, that electrochemically reduces dissolved N2 gas to ammonia in an aqueous electrolyte under ambient conditions. The Faradaic efficiency (FE) achieves 11.56 ± 0.85% at −1.19 V versus the reversible hydrogen electrode, and the maximum production rate is 97.18 ± 7.13 mg hour−1 cm−2. The catalyst contains no noble or rare metals but rather has a surface composed of sharp spikes, which concentrates the electric field at the tips, thereby promoting the electroreduction of dissolved N2 molecules near the electrode. The choice of electrolyte is also critically important because the reaction rate is dependent on the counterion type, suggesting a role in enhancing the electric field at the sharp spikes and increasing N2 concentration within the Stern layer. The energy efficiency of the reaction is estimated to be 5.25% at the current FE of 11.56%.

Original languageEnglish
Article numbere1700336
JournalScience Advances
Volume4
Issue number4
DOIs
StatePublished - Apr 27 2018

Funding

The synthesis, materials science, and electrochemistry supporting this work were conducted at the Center for Nanophase Materials Sciences, which is a U.S. Department of Energy (DOE) Office of Science User Facility. This work used computational resources of the National Energy Research Scientific Computing Center, which are supported by the Office of Science of the DOE under contract no. DE-AC02-05CH11231. A portion of this research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231.

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